Klotho is a transmembrane protein acting as a co-receptor for FGF-23 and thus exerts clinical actions on mineral metabolism. The association of secreted Klotho with outcomes in CKD patients is unclear. This study examined the relation between plasma Klotho and cardiovascular events in dialysis patients, accounting for common and CKD-MBD related risk factors, arterial stiffness and atherosclerotic burden.Seventy-nine chronic hemodialysis patients were observed for a median follow-up of 5.5 years. Klotho levels as well as carotid–femoral pulse wave velocity (cfPWV) and common carotid intima-media thickness (ccIMT) measurements were performed at baseline. The primary end-point was first occurrence of all-cause death, non-fatal myocardial infarction or non-fatal stroke. Secondary end-points were: (i) all-cause mortality; (ii) cardiovascular mortality; (iii) a combination of cardiovascular death, non-fatal MI, non-fatal stroke, resuscitation after cardiac arrest, coronary revascularization, heart failure hospitalization and atrial fibrillation.p = 0.017); HR: 2.137, 95%CI 1.124–4.065. Cumulative survival was insignificantly lower , but cumulative cardiovascular survival  and cumulative freedom from the cardiovascular composite outcome  were significantly lower in the low-Klotho group. In modelled Cox-regression analysis the association of low Klotho with the primary endpoint remained significant after stepwise adjustment for cFGF3, PTH, Ca x P product, established risk factors  as well as cfPWV and ccIMT .Cumulative freedom from the primary endpoint was 31% for the low-Klotho group (≤745 pg/ml) and 53% for the high-Klotho group (logrank Low Klotho is associated with cardiovascular events in hemodialysis patients, independently from factors associated with mineral-bone disease, common risk factors and intermediate outcomes, such as cfPWV and ccIMT. Patients with chronic kidney disease (CKD) are at increased cardiovascular risk due to the presence of atherosclerosis and arteriosclerosis in the vascular wall , 2. The Klotho is a 130 kDa transmembrane protein, expressed predominantly in the distal convoluted tubules of the kidneys, but also in many other organs, which is involved in the regulation of human aging . The extSecreted Klotho has been associated with cardiovascular events and mortality in the general population and various sub-populations (i.e. the elderly or patients with diabetes) , 17, howIn the aforementioned studies, no evaluations of intermediate outcomes such as the degree of atherosclerosis or arteriosclerosis were performed. Thus, this study aimed to examine the possible relationship between Klotho levels and cardiovascular outcomes in hemodialysis, with simultaneous exploration of possible confounding effects from common risk factors, FGF-23 and other CKD-MBD variables, PWV and ccIMT.Following a prospective cohort design, this study included patients on maintenance hemodialysis of the Dialysis Unit of the Department of Nephrology, Hippokration General Hospital and an affiliated Dialysis Unit in the city of Thessaloniki. Adult patients (i.e. > 18 years of age) undergoing maintenance hemodialysis thrice weekly for ≥3 months, were eligible to participate. All patients signed an informed consent. Exclusion criteria were: the presence of malignancy, acute infection, hepatic or chronic inflammatory disease, active antibiotic, corticosteroid or immunosuppressive treatment, previous parathyroidectomy and cardiac arrhythmias. The protocol procedures were conducted in accordance with the Declaration of Helsinki. The study was approved by the Ethics Committee of the School of Medicine, Aristotle University of Thessaloniki.Baseline evaluation was performed between March and December 2010 and included a full medical history and physical examination. Demographics, dialysis-related parameters, and co-morbid conditions were recorded. Study procedures were performed in a midweek non-dialysis day, i.e. the day before the second or the third weekly session. Participants were instructed to refrain from smoking, heavy exercise, caffeine and alcohol consumption for 2 h before the examination. All measurements were performed by the same well-trained operator in a quiet room with stable air temperature (approximately 22 °C) after at least 10 min of rest, as described elsewhere .Βlood pressure (BP) was measured in a sitting position in the non-fistula or the non-dominant arm after 10 min of rest with a validated oscillometric device and a cuff of appropriate size. Each patient’s systolic BP (SBP) and diastolic BP (DBP) was the mean value of three consecutive measurements within 5 min. Pulse pressure (SBP-DBP) and mean arterial pressure [SBP + 2(DBP)]/3 were estimated.Carotid–femoral PWV was measured in each patient in a supine position with the SphygmoCor device  which uses an applanation tonometry transducer , as described elsewhere . This inUltrasonographic evaluation of intima-media thickness (IMT) was performed by an Aloka Prosound A6 device , with high resolution B-mode 10 MHz transducer . BilaterBlood samples were collected on the day immediately following the study assessment day, prior to a midweek dialysis session. Routine laboratory parameters were measured directly and samples for Klotho and FGF-23 were immediately centrifuged and stored in − 80 °C. Complete blood count, calcium, phosphate, albumin, cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, alkaline phosphatase, urea and creatinine values, were measured with routine methods in an automated laboratory analyzer . Serum CRP levels were measured using nephelometry, and intact PTH levels with radioimmunometric method . Plasma Klotho was measured by a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) . Plasma levels of intact FGF-23 and large C-terminal fragments of FGF-23 were determined using two site second-generation sandwich ELISA  all-cause mortality; (b) cardiovascular mortality, which was defined as fatal MI (death by cardiovascular mechanisms occurring in 30 days and regarded as a consequence of the MI) or fatal stroke (death occurring in 30 days and regarded as a consequence or a complication of the stroke) or sudden death; (c) a combined outcome that included cardiovascular death, non-fatal MI, non-fatal stroke, resuscitation after cardiac arrest, coronary revascularization, hospitalization for heart failure or atrial fibrillation (AF).p < 0.05 (two-tailed) were considered statistically significant in all comparisons. Hazard ratios (HRs) with 95% confidence intervals (CIs) are reported. Statistical analysis was performed using the Statistical Package for Social Sciences version 25.0 .The study population was dichotomized based on the median plasma Klotho level (745 pg/mL). Quantitative variables are presented as mean ± standard deviation and qualitative variables as frequencies and percentages . The Shapiro-Wilk test was applied to examine the normality of distribution for continuous variables. Comparisons of continuous parameters between the groups of interest were performed with the paired Student’s t-test for independent variables or the Mann-Whitney test, as appropriate. Comparisons for categorical variables between-groups were performed with the Chi Square (χ2) test or the Fisher’s exact test. Kaplan–Meier curves and life tables were created, and the log-rank test was applied to compare the differences between the two groups of Klotho in the occurrence or freedom from the studied endpoints during follow-up. Univariate Cox regression analysis was used to evaluate the univariate association of low-Klotho with the study endpoints. Furthermore, we examined the possible confounding effect of various parameters, such as intact and c-terminal FGF23, PTH, cfPWV, ccIMT, demographic and clinical characteristics and laboratory parameters that could interfere at the association between Klotho and the primary endpoint with a modelled Cox regression analysis (enter method). Values of 2. The primary renal disease was glomerulonephritis in 18 patients (22.8%), diabetic nephropathy in 15 patients (19.0%), obstructive nephropathy in 9 (11.4%), ADPKD in 8 (10.1%), hypertensive nephropathy in 7 (8.9%), other diseases in 3 (3.8%), while in 19 patients (24.0%) the etiology was unknown. Fifty-seven patients were on standard low-flux bicarbonate hemodialysis and 43% patients were treated with hemodiafiltration. Fifty-nine patients (74.7%) were dialyzed through a native arteriovenous fistula, 11 (13.9%) through an arteriovenous graft, while 9 patients (11.4%) had a central venous dialysis catheter. Mean Kt/V value was 1.46 ± 0.21 at baseline.The study population consisted of 79 patients on maintenance dialysis. Baseline demographic, dialysis-related and laboratory characteristics of all participants are displayed in Table p = 0.038), and higher values of ccIMT  compared with those in the high-Klotho group.Study participants were divided in two groups of approximately the same size according to the median Klotho value. Forty patients (50.6%) were assigned to the low-Klotho group (levels≤745 pg/mL), and the rest in the high-Klotho group. As shown in Table The frequencies of all study end-points are summarized in Table p = 0.017). In univariate Cox regression analysis the HR for the occurrence of the primary endpoint in the patients belonging in the low-Klotho group compared to the high-Klotho group was 2.137, 95%CI (1.124–4.065) p = 0.021)  between the two groups of different Klotho levels are shown in Fig. p = 0.107). Cumulative freedom from death of cardiovascular origin was 63% for patients in the low-Klotho group and 88% for those in the high-Klotho group, logrank p = 0.029. Similarly freedom from the composite outcome was 18 and 45%, logrank p = 0.009 for the low-Klotho and high-Klotho groups, respectively.Figure p = 0.113, indicating no-significant difference between groups. However, the risk of cardiovascular death  and the risk of the composite outcome , were significantly higher for patients with low compared to those with high Klotho.In Fig. p = 0.021). This association remained significant after step-wise adjustment for cFGF-23, used as a dichotomous variable with the group of patients with high levels acting as the reference group . Since a strong correlation was observed between the intact and the c-terminal FGF-23 , the results are essentially the same as if iFGF-23 were used (data not shown). The association of low Klotho with the primary outcome continued to be significant as cFGF-23 and PTH , and cFGF-23, PTH and Ca x P product  were added. The association under study was not altered even after several common risk factors  were included in the model , and it remained significant and of the same magnitude after the addition of the two intermediate outcomes, that are established risk factors of cardiovascular disease and death, i.e. cfPWV and ccIMT .Table p = 0.107), a fact that could be attributed to the low event rate. Most importantly, in stepwise Cox regression analysis the association of low Klotho with the primary outcome stayed significant after stepwise adjustment for cFGF3, PTH, Ca x P product, established risk factors  as well as cfPWV and ccIMT, which are intermediate cardiovascular endpoints with known association with hard outcomes in this population.The present study examined the association between secreted Klotho and cardiovascular outcomes in hemodialysis patients, while simultaneously exploring the possible confounding effects caused by common and CKD-MBD related risk factors, the arterial stiffness and atherosclerotic burden. We observed that cumulative freedom from the primary endpoint, cardiovascular survival and freedom from the cardiovascular composite endpoint were significantly lower for patients in the low-Klotho group compared to those in the high-Klotho group. Overall survival was also lower in patients with low-Klotho but the between-group difference did not reach significance  individuals observed during 6 years, patients with Klotho level in the lowest tertile (< 575 pg/mL) had an increased risk of death compared with participants in the higher quartile (> 763 pg/mL)  . In a mumponents .p = 0.008), compared with patients with Klotho < 280 ng/L. This effect remained significant  after adjustment for a number of relevant cardiovascular risk factors [With regards to patients with CKD, Seiler et al. have previously, shown in 312 patients with CKD stages 2 to 4, that levels of Klotho did not predict the occurrence of death or the initiation of renal replacement therapy during 2.2 years,  cardiovascular disease in individuals with CKD through mechanisms that are distinct from known cardiovascular risk factors. Future studies are expected to shed more light in the exact role of secreted Klotho in cardiovascular outcomes in these patients.


The pulmonary artery catheter (PAC) is used for perioperative management in patients undergoing cardiovascular surgery, although its application still remained controversial –3. We ro2 Catheter 744HF75, Edwards Lifesciences, Irvine, CA, USA) was inserted through the right internal jugular vein. First, the introducer sheath was placed via the right internal jugular vein in the Trendelenburg position, and then the PAC was started floating through the sheath by monitoring the pressure waveform in the flat position. The PAC was inserted approximately 20 cm, and central venous pressure (CVP) waveform was confirmed, subsequently the balloon was inflated with 1.5 ml of air. With inflated balloon, the catheter was floated into the PA. The waveform of the PA was first observed followed by inserting the catheter approximately 2–3 cm forward and deflated the balloon. In this position, after confirming that the tip of the catheter was not wedged into the PA, it was locked with the sheath.The current study was approved by the institutional review board, and informed consent was obtained from all eligible patients. It was registered in the UMIN Clinical Trial Registry (UMIN000030025). This study was conducted from November 2014 to October 2017 at Sakurabashi-Watanabe hospital in Osaka, Japan. We prospectively examined the time required for the PAC placement in 400 adult patients undergoing elective cardiovascular surgery. All patients were monitored electrocardiogram, invasive arterial pressure, oxygen saturation, and end-tidal carbon dioxide. After induction of anesthesia with midazolam, fentanyl or remifentanil, and vecuronium, mechanical ventilation was started following tracheal intubation. Anesthesia was maintained with propofol or sevoflurane combined with remifentanil and fentanyl. The PAC .P < 0.05 was considered statically significant.Before the study started, we planned to collect 400 cases and then to perform sample size calculation. As a result, we had available results in these 400 cases and waived power of analysis. The successful rate of the PAC placement was expressed in percentages and was analyzed by Fisher’s exact test followed by a Bonferroni multiple comparisons to specify differences between groups. The placement times were expressed as median and interquartile range and analyzed by Kruskal-Wallis test followed by Mann-Whitney test with Bonferroni multiple comparisons to specify differences between groups. The statistical analysis was performed by SPSS  version 14.0. P < 0.001). We placed the PAC under X-ray fluoroscopic photographing system in other three cases. On the other hand, the placement in patients with transvenous pacemaker leads was not significantly different from that of the control. We encountered only one patient with pulmonary artery stenosis. He was a 70-year-old male and was scheduled for aortic valve replacement. He was diagnosed as tetralogy of Fallot at birth and underwent radical operation at 29 years. He had residual systolic pressure gradient of 30 mmHg between the pulmonary artery and the right ventricle  was 379. The successful rate and PAC placement time in each category is shown in Table The present data reconfirmed that placement of a PAC is difficult in patients with history of tricuspid ring annuloplasty. On the other hand, placement of a PAC by monitoring the pressure waveform is possible in patients with the transvenous pacemaker leads.According to the previous case reports , 6, one One previous case report suggested that transvenous pacemaker leads may be a possible obstacle to hinder the PAC placement . HoweverUnfortunately, we could encounter only one case with pulmonary stenosis. Thus, we cannot conclude whether the PAC placement is possible by monitoring the pressure waveform. However, based on our experience of this one case, we have an impression that we are worth placing the catheter with the pressure monitoring in a patient with pulmonary stenosis at first. With future accumulating the similar cases, a conclusion will be provided.We have to discuss potential limitations in our study. Although we collected the subjects for 3 years, the number of patients having obstruction in the passage of the PAC was small. Our results are dependent on the data we accumulated during the study period, so the clinical significance of our results would be interpreted with caution. We have to acknowledge the possibility that accumulation of further number of subjects would change our conclusion in the future.In conclusion, placement of a PAC by monitoring the pressure waveform is difficult in a patient with history of tricuspid ring annuloplasty and the placement under X-ray fluoroscopic photographing system is recommended. On the other hand, the placement by monitoring the pressure waveform may be available in a patient with transvenous pacemaker leads.


The SmO2 of leg muscles was lower than that of ventilatory muscles because SmO2 was calculated as HbO2/(HHb+HbO2), and the HHb of leg muscles was relatively higher than the HbO2 of leg muscles. The healthy subjects had higher SmO2, the patients with COPD had higher HHb, and the patients with CHF had lower HbO2 in both muscle groups throughout the tests. The patients with CHF had lower SmO2 of ventilatory muscles than the patients with COPD at peak exercise (p < 0.01). We conclud that fd-NIRS can be used to discriminate tissue oxygenation of different musculatures and disease entities. More studies on interventions on ventilatory muscle oxygenation in patients with CHF and COPD are warranted.Patients with chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF) often have dyspnea. Despite differences in primary organ derangement and similarities in secondary skeletal muscle changes, both patient groups have prominent functional impairment. With similar daily exercise performance in patients with CHF and COPD, we hypothesized that patients with CHF would have worse ventilatory muscle oxygenation than patients with COPD. This study aimed to compare differences in tissue oxygenation and blood capacity between ventilatory muscles and leg muscles and between the two patient groups. Demographic data, lung function, and maximal cardiopulmonary exercise tests were performed in 134 subjects without acute illnesses. Muscle oxygenation and blood capacity were measured using frequency-domain near-infrared spectroscopy (fd-NIRS). We enrolled normal subjects and patients with COPD and CHF. The two patient groups were matched by oxygen-cost diagram scores, New York Heart Association functional classification scores, and modified Medical Research Council scores. COPD was defined as forced expired volume in one second and forced expired vital capacity ratio ≤0.7. CHF was defined as stable heart failure with an ejection fraction ≤49%. The healthy subjects were defined as those with no obvious history of chronic disease. Age, body mass index, cigarette consumption, lung function, and exercise capacity were different across the three groups. Muscle oxygenation and blood capacity were adjusted accordingly. Leg muscles had higher deoxygenation (HHb) and oxygenation (HbO Exercise intolerance and exertional dyspnea are often encountered in patients with chronic obstructive pulmonary disease (COPD) and cardiovascular diseases, and especially in those with congestive heart failure (CHF) . The symMuscle function depends primarily on perfusion, muscle mass, fiber composition, and energy metabolism . HoweverWith advances in NIRS technology, frequency-domain NIRS (fdNIRS) is capable of providing absolute values rather than relative changes in value . This imIn this observational study, we compared oxygenation and perfusion in two local musculatures during exercise as measured by near infrared spectroscopy (NIRS) across three groups of participants . The local Institutional Review Boards of Chung Shan Medical University Hospital (CS11144 and CMRPG32058) approved this study, which was conducted in compliance with the Declaration of Helsinki. Signed informed consent was obtained from each participant. The study was registered at Chung Shan Medical University Hospital (CSH-2012-C-23).1/FVC) ≤0.7, and no significant bronchodilation in a stable condition. Stable CHF was defined as stable heart failure with a mid-range or reduced ejection fraction  with or without peripheral vascular disease as confirmed by the cardiologists of the institutes [Adult subjects were screened, enrolled, and allocated into COPD, CHF, and control groups from two university hospitals in Taiwan if they agreed to participate in the study. COPD was defined according to the GOLD guideline as follows : a histostitutes . Healthystitutes , other cThe subjects used the oxygen-cost diagram (OCD)  to asses1, total lung capacity (TLC), and diffusing capacity for carbon monoxide (DLCO) were measured using spirometry and body plethysmography in accordance with the currently recommended standards.FEV2, mL/min), CO2 output , minute ventilation (E), blood pressure, oxyhemoglobin saturation assessed by pulse oximetry (SPO2), blood pressure, and Borg dyspnea score were measured.Each subject completed a ramp-pattern exercise test from resting to unloading, and the limit of their tolerance. Work rate was selected at a rate of 5–20 watts/minute depending on their fitness so that they could complete the loaded exercise within 8–12 min. Their fitness was evaluated using an OCD scale, and the ramp slope was selected on the basis of their fitness . The timTM system  was used to measure deoxygenated and oxygenated hemoglobin and intracellular myoglobin (HHb+HMb and HbO2+MbO2) [2 instead of HHb+HMb and HbO2+MbO2. The distance between the transmitter and receiver optodes of the NIRS system was 4 cm. NIRS is usually expressed by relative values instead of absolute values. However, the OxiplexTSTM system can provide absolute values of tissue saturation in real time [2, the sum of both , and tissue saturation or the tissue oxygenation index . As TOT cannot be used to represent blood flow [2 as the total blood capacity, which included arterial, capillary, and venous blood volumes. A calibration block was used before each test as recommended by the manufacturer. The leg probe of the OxiplexTSTM system was positioned over the vastus lateralis muscle 10–12 cm above the knee, parallel to the major axis of the thigh [2 and more [An OxiplexTSO2+MbO2) ,33. EvenO2+MbO2) , for simeal time ,35, and ood flow , we defihe thigh , and thehe thigh  to monithe thigh . We selehe thigh  and duriand more ), and beand more ,43. A piand more ,45.mO2 was 5.5 with a standard deviation for the normal and CHF groups of 4 and with a significance level of 0.05 and a power of 0.8 [p values were calculated by analysis of variance (ANOVA) with Tukey’s correction for multiple comparisons to compare means across the three groups. The paired t test was used to compare two related means between different time points. Fisher’s exact method was used in a contingency table analysis for categorical variables. Muscle mass is related to age, body height and weight [p < 0.05.Data were summarized as mean ± standard deviation. The sample size was estimated to be at least 10 for each group when the population mean difference in Sr of 0.8 . For eacd weight ,48,49, ad weight ,42,50 anp = NS). The etiologies of CHF are shown in PO2 and performance of peak exercise in the three groups are shown in A total of 175 subjects were screened and 134 subjects were retained for analysis after excluding 41 subjects . The sub2, and TOT and higher SmO2 values at rest and during unloaded and loaded exercise , whereas the COPD group tended to have higher HHb (p < 0.1) and the CHF group tended to have lower HbO2 (p < 0.1) and TOT  but did not significantly change HbO2, thereby significantly increasing TOT and decreasing SmO2 . Across the three groups, differences in the Hb variables during unloaded and loaded exercise were the same as at rest. Unloaded exercise did not change the four variables for all subjects, except that TOT and SmO2 were slightly increased in the COPD group , thereby slightly decreasing TOT (p < 0.1–0.001) and significantly decreasing SmO2 (p < 0.05–0.0001). The CHF group had significantly lower SmO2 than the COPD group at peak exercise (p < 0.01).At rest, the healthy subjects had modestly higher or tended to have higher HbOPD group . Loaded mO2 levels obtained from the two musculatures had the best correlations with the demographic, lung function and CPET data at peak exercise compared to the other three Hb variables. For simplicity, only SmO2 was reported. Nadir SmO2 of the leg muscles was related to age , maximal inspiratory pressure (MIP) %pred (r = 0.47), and some peak exercise variables, including heart rate (r = 0.30), E/maximal voluntary ventilation (MVV) ratio (r = −0.30), Borg score (r = −0.49), SPO2 (r = 0.37), and nadir E/2 (r = −0.30). Nadir SmO2 of the ventilatory muscles was related to age (r = −0.30), OCD (r = 0.29), cigarette smoking (r = −0.26), MIP %pred (r = 0.56), and some peak exercise variables including heart rate (r = 0.29) and E/MVV ratio (r = −0.34).Nadir S2 and TOT but lower SmO2 than the ventilatory muscles throughout the tests. In addition, the healthy controls had higher levels of SmO2 and HbO2 in both muscles throughout the tests, whereas the COPD group had higher HHb levels and the CHF group had lower HbO2 levels, which is consistent with a previous report [2, thereby increasing TOT and decreasing SmO2 in the leg muscles. However, loaded exercise conversely decreased HbO2 and TOT in the ventilatory muscles and decreased SmO2 to a lower level in the diseased subjects than in the healthy subjects (p < 0.01) and to a further lower level in the CHF group (p < 0.01). The correlation study revealed some factors that were detrimental and others beneficial to SmO2 and by interventions, the SmO2 might be improved , despite the workload being “~zero” watts, and pump HHb blood into veins and thus decrease HHb but preserve HbO2 , thereby decreasing TOT and increasing SmO2. Oxygen consumption and total blood flow during this time cannot be lower than those at rest, so that HHb is not only an indicator of oxygen consumption but also an indicator of venous blood that is pumped away  or stored if any  and therefore, TOT cannot represent blood flow but blood capacity (or volumes) of the tissue of interest [2 diffusion as “flux of O2 driven by O2 pressure differential between the capillary and the intramyocyte milieu operating against a finite O2 diffusing capacity” [2 and HHb represents the balance between oxygen supply and extraction, and it probably resembles the meaning of SmO2, although not mathematically [2 = x1ΔA780 + y1ΔA805 + z1ΔA830 and HHb = x2ΔA780 − y2ΔA805 − z2ΔA830  [2 and HHb values without providing the formula using the wavelengths [However, muscle metabolism or blood flow cannot be evaluated using NIRS without performing arterial or venous occlusion ,56,57,58interest ,44,53,54interest  and Terainterest ,59 used apacity” , which iatically ,58. Of natically , whereasatically , Manciniatically ,37, and 2 and HHb and TOT in the leg muscles compared to the ventilatory muscles, which is compatible with a previous study [mO2 was higher in the ventilatory muscles than in the leg muscles in this study. We speculate that the high SmO2 in the ventilatory muscles may be related to type I/II ratio, capillary/muscle density or capillary/myofibril ratio. Aerobic muscle enzyme activities have been reported to be higher in the ventilatory muscles in patients with COPD and CHF, whereas some anaerobic muscle enzyme activities have been reported to be higher in the quadriceps femoris [2 [Blood volume has been reported to be higher in leg muscles than in ventilatory muscles ,59. Thisus study . However femoris . In contis [V.O2 . This miis [V.O2 .2 and increased TOT due to the increase in HHb in all participants during loaded exercise, which is consistent with a report by Vogiatzis et al., who used NIRS with the IGD method to study patients with COPD [2 decreased in biceps in response to an incremental forearm contraction in patients with COPD [In the present study, the leg muscles had preserved HbOith COPD . This suith COPD .p = 0.11), and that a unique decrease in SPO2 may contribute to the mechanism in patients with COPD (p = 0.009). This is compatible with a previous study by Lanfranconi et al., who reported that during incremental exercise, changes in HHb at peak exercise and 2peak were lower in heart transplant recipients than in normal controls [2 and heart rate [In the present study, HHb reached a similar level under maximal exercise across the three groups despite the different physiological limitations and exercise loads. This suggests that the peak capability of skeletal muscle oxygen extraction was similar across the three groups at peak exercise with the heart rate/predicted heart rate ratio reaching a similar level  to peak exercise [In the present study, in the ventilatory muscles, loaded exercise decreased both HbOsubjects ,22, sugg reports ,22,59. T reports ,22,38,59exercise ,50. In aexercise . FurthermO2, whereas inspiratory muscle strength and high heart rate and SPO2 at peak exercise were beneficial to SmO2. Thus, reducing ventilation demand/capacity ratio, exercise hyperventilation, and high dyspnea rating with interventions such as exercise training may improve SmO2. On the other hand, improving inspiratory muscle strength and SpO2 and enhancing the capacity of heart rate increase by exercise training and breathing maneuvers with O2 breathing may also improve SmO2. Lastly, 2peak %predicted and peak work rate %predicted were not related to any of the four Hb variables of both musculatures in the present study  in patients with mitochondrial myopathy and McArdle’s disease [In the correlation study, aging, high ventilation demand/capacity ratio, exercise hyperventilation, and high dyspnea rating were detrimental to Snt study , compati disease . In pati disease . In pati disease  or even  disease .2, and TOT between individuals when using fdNIRS, correcting for adipose tissue thickness (ATT) for these variables has been recommended [2 [2. Previous studies have reported skinfolds at the sixth intercostal space and the anterior axillary line ranging from 6.7 ± 2.3 to 6.7 ± 4.6 mm, and a skinfold at the vastus lateralis muscle ranging from 8.6 ± 4.6 to 8.4 ± 2.9 mm in young subjects with a BMI of 21.7 to 23.7 kg/m2 [2 [Age and body mass index were different across the three groups and thus, selection bias may have been introduced. The issue of choosing different exercise increments among the subjects during CPET could have affected the pattern of oxygenation/deoxygenation responses between the three groups and should be considered to be a limitation of the study. Combining the IGD technique and NIRS can improve measurements of the peripheral circulation ,21,22. Gommended . In our ended [2 . As thigended [2 , this is.7 kg/m2 ,17, and kg/m2 [2 . Althougkg/m2 [2 . The cutkg/m2 [2 ; howeverkg/m2 [2 . To disckg/m2 [2 , high-pomO2 in response to loaded exercise between locomotor and ventilatory muscles were related to the type of disease. When performing peak exercise, more attention should be paid to ventilatory muscles in patients with cardiopulmonary diseases, especially those with CHF.This study differentiates the Hb oxygenation status of locomotor and ventilatory muscles between healthy and diseased subjects using frequency domain NIRS which can yield absolute values. The status of Hb oxygenation was different in different musculatures, and changes in oxygenation and STo better understand the potential mechanisms orchestrating dynamic muscle oxygenation in different types of diseases, directly measuring cardiac output, systemic oxygen delivery, leg and ventilatory muscle blood flow and oxygen delivery, and muscle mass morphological and structural changes and molecular mechanisms of muscle atrophy concomitantly with tissue monitoring with near infrared spectroscopy is warranted. This may be also suitable for interpreting the effects of pharmacological and non-pharmacological interventions in patients with exertional dyspnea.


To evaluate the predictive value of mean perfusion pressure (mPP) in thedevelopment of acute kidney injury (AKIN) after transcatheter aortic valveimplantation (TAVI).One hundred and forty seven consecutive patients with aortic stenosis (AS)were evaluated for this study and 133 of them were included. Mean arterialpressure (mAP) and central venous pressure (CVP) were used to calculate mPPbefore TAVI procedure (mPP = mAP-CVP). The occurrence of AKIN was evaluatedwith AKIN classification according to the Valve Academic ResearchConsortium-2 recommendations. The patients were divided into two groupsaccording to the receiver operating characteristic (ROC) analysis of theirmPP levels (high-risk group and low-risk group).The AKIN prevalence was 22.6% in this study population. Baseline serumcreatinine level, glomerular filtration rate, amount of contrast medium, andthe level of mPP were determined as predictive factors for the developmentof AKIN.The occurrence of AKIN is associated with increased morbidity and mortalityrates in patients with TAVI. In addition to the amount of contrast mediumand basal kidney functions, our study showed that lower mPP was stronglyassociated with development of AKIN after TAVI. Surgical aortic valve replacement (SAVR) iscurrently considered the gold standard treatment for severe symptomaticAS.Transcatheter aortic valve implantation (TAVI) has emerged as an alternative tosurgery for patients with severe symptomatic AS, particularly for those who wereconsidered at intermediate to high risk for surgery,4. Since its introductionin 2002, more than 200,000 patients have undergone TAVI globally.Aortic stenosis (AS) is one of the most common cardiac degenerative valvulardiseases, with a prevalence of 3-5% in patients above 75 years ofage,6.Ageing, preexisting impaired kidney function, hemodynamic instability, congestiveheart failure (CHF), diabetes mellitus (DM), anaemia, and the usage of great amountof contrast mediums (CM) are well-known risk factors for the development of acutekidney injury (AKIN) after TAVIAlthough these risk factors have been well known, the predictive value of meanperfusion pressure (mPP) in the development of AKIN has not been investigated yet.Therefore, in this study, we aimed to evaluate the predictive value of mPP in thedevelopment of AKIN after TAVI.2, had decompensated heart failure, received inotropic agents, hadintra-aortic balloon pump, and received CM within the last 48 hours were excluded.Patients who had undergone additional procedures or received additional CM due tovascular complications, and had chronic pulmonary diseases or chronic liver diseaseswere also excluded from the study. Intravenous hydration therapy was started inpatients with GFR <50 ml/min/1.73 m2 for 12 hours before the procedureand continued for 24-48 hours after TAVI. Patients' daily blood tests includingcreatinine were checked for three days before and three days after TAVI.In this study, 147 consecutive patients who had undergone TAVI procedure in ourclinic between June 2013 and December 2015 were evaluated. One hundred and thirtythree of them met the inclusion criteria and were included in this study. Patientswho had invasive blood pressure monitorization, jugular venous catheter, and werehemodynamically stable were included in our study. Patients who had undergone renalreplacement therapy, presented glomerular filtration rate (GFR) <30 ml/min/1.73mBlood pressure of every patient was monitored using invasive monitorizationduring the 12 hours before TAVI procedure. Also during this period, meanarterial pressure (mAP) calculated by monitors was entered in patient files.Central venous pressure (CVP) was monitored with catheters implanted byanesthesiologists in all patients before valve implantation. The mPP wascalculated using the formula MPP = mAP-CVP.. VARC-2 recommends that the AKINsystem should be used to diagnose AKIN. According to the AKIN system:The Valve Academic Research Consortium-2 (VARC-2) criteria were used to evaluateany complication occuring in TAVI patientsAKIN Stage 1: Increase in serum creatinine of 150-199% (1.5-1.99× increase compared with baseline) or increase of ≥0.3mg/dL (≥26.4 mmol/L) or urine output <0.5 mL/kg/h for>6 h but <12 h;AKIN Stage 2: Increase in serum creatinine of 200-299% (2.0-2.99× increase compared with baseline) or urine output <0.5mL/kg/h for >12 h but <24 h;AKIN Stage 3: Increase in serum creatinine of ≥300% (>3× increase compared with baseline) or serum creatinine of≥4.0 mg/dL (≥354 mmol/L) with an acute increase of atleast 0.5 mg/dL (44 mmol/L) or urine output <0.3 ml/kg/h for>24 h or anuria for >12 h.2, andvalve area index  <0.6 cm2 wereconsidered to be severe AS. The balloon-expandable Edwards Sapien XTvalve  was used for TAVI process.Vascular occlusion device  was used in eligible patients in terms of femoral artery diameterand anatomy. The surgical cut-down method was applied in patients who wereunsuitable for using iliac and femoral artery anatomy vascular closure device.Transoesophageal echocardiography and multislice computed tomography (CT) testswere done to determine the diameter of the aortic bioprosthesis implanted. Inall patients, clopidogrel 75 mg and acetylsalicylic acid 100 mg were startedbefore TAVI procedure. İohexol , a nonioniclow-osmolar monomeric CM, was used as the opaque material. The amount of CM wasrecorded during all TAVI procedure. Examinations such as CT and coronaryangiography that required administration of CM, except TAVI procedures, wereperformed at least 72 hours before. Daily kidney function tests of all patientswere monitored in our centre from admission to discharge. Creatinine levels werechecked in the second week, and the first, third, sixth and twelfth month afterTAVI procedure .Severe AS was diagnosed with echocardiographic methods. The situations of averageaortic gradient > 40 mmHg, aortic valve area (AVA) <1 cmThe patients were prospectively followed during one year after TAVI. The informedconsent form was obtained from each subject, and the study was conducted inaccordance with the Helsinki Declaration. The study protocol was approved by thelocal ethics committee.Based on the receiver operating characteristic (ROC) analysis, patients who hadlower mPP values (<72 mmHg), which was determined as the threshold value forAKIN development, were included in the high-risk group (HR-G), and those who hadhigher mPP values (≥72 mmHg) were included in the low-risk group (LR-G).Additionally, characteristics of patients with normal renal functions (NRF) andthose who developed AKIN were evaluated.2 test and Fisher exact test were used to comparecategorical variables. Univariate analyses were performed with the variables,such as age (years), left ventricular ejection fraction (%), mean aorticgradient (mmHg), Society of Thoracic Surgeons (STS) score (%), logisticEuroSCORE (%), mPP (mmHg), systolic blood pressure , diastolic bloodpressure , DM (%), hypertension (%), coronary artery disease , creatinine (mg/dl), GFR (ml/dk/1.73 m2), amount of CM (ml),pre-TAVI haemoglobin levels (g/dl), and red blood cell transfusion after TAVI(%). The backward stepwise multivariate regression analysis was performed withthe variables of mPP, left ventricular ejection fraction, baseline creatinine,GFR, red blood cell (RBC) transfusion, amount of CM, SBP, and DBP; theP values of those was found to beP<0.10, by univariate analyses. A ROC curve analysis wasperformed to identify the optimal cut-off point of mPP to predict AKIN inpatients with severe AS. The area under the curve (AUC) values were calculatedas a measure of test accuracy. A two-sided P<0.05 wasconsidered significant within a 95% confidence interval (CI). Kaplan-Meiersurvival plots were constructed from the index procedure and up to one yearafter that and compared using the log-rank test. P values<0.05 were accepted as statistically significant.Statistical analysis was performed using SPSS 17.0 software . The Kolmogorov-Smirnov test was used to assess the normality ofdistributions. Variables not normally distributed were expressed as medians(interquartile ranges). Normally distributed continuous variables were expressedas a mean ± standard deviation. The means for normally distributedcontinuous variables were compared by independent-samples t-tests.Skew-distributed continuous variables were compared using a Mann-Whitney U test.Pearsons x2, and the mean value of left ventricular ejectionfraction was 42 ±14.7%.One hundred and thirty three patients  were enrolled in this study. AKIN was recorded in 30 patients after TAVI(22.6%). Mean values of SBP, DBP, mAP, and mPP were lower in HR-G and AKINgroups. The mean value of CVP was higher in HR-G and AKIN groups. The averagemean gradient of the aortic valve was 49.7±11.7 mmHg, the mean AVA was0.65±0.11 cmA balloon-expandable Edwards SAPIEN XT valve was implanted via transfemoralaccess in all patients. The mean radiation time was 7.6±3.1 min. Mean CMand duration of procedure were 143.4±22.7 ml and 69.2±28.1 min,respectively. There weren't any significant difference between the two groupsaccording to the numbers and durations of the rapid ventricular pacing.vs. 76.3±7.4 P<0.001). Age,gender, DM, hypertension, chronic obstructive pulmonary disease (COPD), CAD,moderate to high grade aortic regurgitation (AR) after TAVI, risk scores forTAVI, haemoglobin, cardiac systolic functions, mean aortic gradient, kidneyfunction tests, amount of CM, previous coronary bypass surgery, and percutaneouscoronary intervention (PCI) rates were similar between the two groups. SBP, DBP,mAP, and mPP levels were significantly lower in HR-G group, but CVP level washigher in HR-G group . After TAVIprocedure, 2 (2.2%) patients needed permanent pacemaker implantation due toatrioventricular conduction block. Transfusion rates were higher in the AKINgroup . Patients in AKINand NRF groups did not show a significant difference in terms of diuretic,renin-angiotensin-aldosterone blocker, and beta-blocker therapy . Eight patients died during the study period.Total mortality was higher in the AKIN group than in the NRF group . Thus, the multivariate regression analysis was performed withthese variables; baseline creatinine, baseline GFR, amount of CM, and mPP werefound to be significant predictors of AKIN  patients developed AKIN after TAVI. Excessive CM usage, hypotension,rapid ventricular pacing, balloon aortoplasty, valve implantation, and embolisationof aortic plaque are considered intra-operative risk factors for AKIN afterTAVI,14.Development of AKIN is strongly associated with increased major adverse cardiacevents after TAVI procedure. Several studies demonstrated that CM/GFR andCM/creatinine clearance (CrCl) rates in invasive procedures are predictors of renalfailure-18. It can be useful to calculate basal GFR and CrClbefore TAVI, to be used to calculate upper limits for CM. The mAP might be decreasedbelow 50 mmHg during rapid ventricular pacing. These hypotensive stages cancontribute to the development of AKIN. Therefore, number and duration of rapidventricular pacing used for our patients during TAVI were recorded in our study.Although basal kidney function tests are important for impairment of renal function,other factors, such as mPP, amount of CM, and rapid ventricular pacing, should bekept in mind to predict renal impairment.As it is well known, CM reduce oxygen availability to the renal medulla and causerenal ischemia,19. Renal perfusion pressure is the most importantpredictor of renal blood flow. A normal renal perfusion pressure should be between60 and 100 mmHg. However, there isn't any non-invasive method thatcan directly measure it. Renal perfusion pressure can be estimated using mPP, mAP,and CVP levels. Especially, mPP calculated with mAP and CBP is shown to be animportant indicator for the continuation of NRF. A strong associationhas been demonstrated between mPP levels and GFR in variousdiseases. Based on the study results, mPP values obtainedwith invasive monitorization in advanced AS patients were found to be a significantfactor in predicting the development of AKIN. The predictive value of AKINdevelopment was calculated as 72 mmHg using ROC analysis . Thecalculation of mPP is based on the difference between mAP and CVP. Since mAP valuesof the HR-G group were lower and CVP values were higher, mPP values in this groupwere low  were strongly associated with the development of AKIN after TAVI.Further studies are needed to evaluate the association between mPP and AKIN inpatients treated with TAVI.


Patients with chronic kidney disease (CKD) are at high risk of end-stage kidney disease (ESKD). The Kidney Failure Risk Equation (KFRE), which predicts ESKD risk among patients with CKD, has not been validated in primary care clinics in Southeast Asia (SEA). Therefore, we aimed to (1) evaluate the performance of existing KFRE equations, (2) recalibrate KFRE for better predictive precision, and (3) identify optimally feasible KFRE thresholds for nephrologist referral and dialysis planning in SEA.All patients with CKD visiting nine primary care clinics from 2010 to 2013 in Singapore were included and applied 4-variable KFRE equations incorporating age, sex, estimated glomerular filtration rate (eGFR), and albumin-to-creatinine ratio (ACR). ESKD onset within two and five years were acquired via linkage to the Singapore Renal Registry. A weighted Brier score (the squared difference between observed vs predicted ESKD risks), bias (the median difference between observed vs predicted ESKD risks) and precision (the interquartile range of the bias) were used to select the best-calibrated KFRE equation.The recalibrated KFRE  performed better than existing and other recalibrated KFRE equations in terms of having a smaller Brier score , less bias , and improved precision . Area under ROC curve for the Recalibrated Pooled KFRE SEA equations were 0.94  at 5 years and 0.96 (95% CI: 0.95 to 0.97) at 2 years. The optimally feasible KFRE thresholds were > 10–16% for 5-year nephrologist referral and > 45% for 2-year dialysis planning. Using the Recalibrated Pooled KFRE SEA, an estimated 82 and 89% ESKD events were included among 10% of subjects at highest estimated risk of ESKD at 5-year and 2-year, respectively.The Recalibrated Pooled KFRE SEA performs better than existing KFREs and warrants implementation in primary care settings in SEA. Using eGFR < 40 mL/min/1.73m2 would identify 5283 (30%) patients requiring referral to a nephrologist, and this number was substantially higher than the 3506 (20%) of KFRE > 10%, and 2308 (13%) of the Youden Index-determined KFRE > 16%. Moreover, using KFRE thresholds ranging 10–16%, nephrologists need to evaluate 5.6 (5.0–6.0) to 7.8 (7.2–8.5) patients with CKD to find one ESKD case, and this resulted in higher referral efficiency than the 12.2 (11.1–13.3) patients using eGFR 40 mL/min/1.73m2. In addition to the higher referral efficiency, KFRE thresholds 10–16% also had similar sensitivity (0.86 [0.85–0.87] to 0.91 [0.90–0.92] vs. 0.88 [0.87–0.89]), higher specificity (0.82 [0.81–0.83] to 0.89 [0.88–0.90] vs. 0.71 [0.70–0.72]), higher PPV (0.10 [0.09–0.11] to 0.16 [0.14–0.18] vs. 0.08 [0.07–0.09]), similar NPV (0.995 [0.980–1.010] to 0.997 [0.990–1.004] vs. 0.995 [0.986–1.004]), and higher LR+ (5.01 [5.00–5.26] to 7.67 [7.14–8.33] vs. 3.03 [2.94–3.13]) compared to eGFR 40 mL/min/1.73m2 , and similar number of patients to be evaluated by nephrologists to find one ESKD case (2.7 [2.4–3.1] vs. 3.2 [2.8–3.6]). In addition, KFRE threshold 45% also had similar sensitivity (0.54 [0.49–0.59] vs. 0.52 [0.48–0.56]), similar specificty (0.99 [0.98–1.00] vs. 0.98 [0.97–0.99]), similar NPV (0.992 [0.982–1.002] vs. 0.991 [0.989–1.001]), similar LR+ (36.8 [25.0–50.0] vs. 26.0 [20.0–33.3]), and higher PPV (0.42 [0.37–0.47] vs. 0.31 [0.27–0.35]) compared to those of eGFR 20 mL/min/1.73m2  for KFRE 10–16% compared to eGFR 30, 40 and 45 mL/min/1.73m2, and the KFRE > 16% corresponded to eGFR < 30 mL/min/1.73m2 approximately  and observed that although using a higher KFRE threshold would refer fewer patients to a nephrologist to find one ESKD case, the sensitivity associated with KFRE also became less optimal  age (40–75 vs. > 75 years), 2) gender, 3) ethnicity , 4) type 2 diabetes mellitus status, and 5) CKD stages at both 5- and 2-year risks. At 5 years, the AUC ranged from 0.82 to 0.96 in the subgroups and at 2 years, the AUC ranged from 0.83 to 0.98 in the subgroups  at 5-year and 0.95 (95% CI: 0.93–0.96) at 2-year risk of ESKD onset.A total of 3241 and 1927 deaths occurred during the 5-year and 2-year follow-ups, respectively. The competing risk and non-competing risk models at 5 years had similar HRs and considerate overlaping 95% CIs (242 [60.4–972] vs. 227 [56.5–909]), suggesting the effect of competing mortality risks is unlikely to affect the ESKD prediction.2. Thus, automated referrals using KFRE thresholds warrant consideration in clinical practice for patients with CKD.Using electronic health records linked with national renal registry, we found that the recalibrated KFRE  had better performance than existing KFRE equations in terms of having a lower Brier score, less bias and improved precision for predicting ESKD in multi-ethnic patients visiting the primary care clinics. The overall predictive capability of the Recalibrated Pooled KFRE SEA for ESKD was significantly higher than using eGFR alone. In addition, 5-year KFRE thresholds ranging 10–16% for nephrologist referral and 2-year KFRE risk threshold at 45% for dialysis planning resulted in high referral efficiency, and substantially improved reclassification of ESKD risks relative to eGFR thresholds of 20, 30, 40 and 45 mL/min/1.73m2. In addition, the 2-year threshold of Recalibrated Pooled KFRE SEA for dialysis planning in the current study (45%) was close to the KFRE > 40% suggested previously [2 [Previous studies showed excellent predictive utility of the Original KFRE equation or the Pooled KFRE equation primarily among patients with European origins or those in nephrology clinics –22. Our eviously  and was ously [2 . MoreoveThe Recalibrated Pooled KFRE SEA equation includes four routinely measured variables, which were available in > 86% of our study population with stage 3–5 CKD . Thus, our findings imply that the Recalibrated Pooled KFRE SEA equation is likely to aid referral decisions and dialysis planning across all general practitioner settings if integrated into EHR. Furthermore, the improved triage efficiency would enable patients at high-risk of ESKD to receive timely referrals to a nephrologist, which has been shown to shorten waiting time for nephrology care  and subsOur study has several strengths. First, this is likely to be the first report to determine the best-calibrated KFRE equation and potentially useful thresholds for nephrologist referral and dialysis planning in primary care population in SEA. When looking for the clinically useful thresholds, we applied rigorous statistical criteria, and combined service-related considerations for health planners, and the methodology provided as a yardstick for future studies. However, whehter the suggested thresholds are optimal for Singapore will need to be further tested taking into consideration of the workforce and work capacticy of Singapore nephrologists, and simulation studies are warranted to predict the performance of such thresholds over time. Second, we included all eligible patients visiting primary care clinics over the study duration and thus had a large sample size. Third, the multiple major ethnic groups in our sample  are a diaspora of populations from countries  that are homes to one-third of the world’s population. The excellent predictive utility of the Recalibrated Pooled KFRE SEA in all three ethnic groups shown in stratified analyses greatly enhanced the utilization of KFRE to many people globally. Fourth, serum creatinine measurements were calibrated to be traceable to an IDMS standard, thus increasing the validity of both eGFR and KFRE assessments. Fifth, we objectively assessed all ESKD cases with virtual follow-up completion via linkage to the nationwide Singapore Renal Registry.However, our study also had some limitations. First, we deleted those without established care from the study (~ 30%), thus introducing the possibility of selection bias. Nevertheless, the prevalence of hypertension and diabetes was lower in the excluded population than that expected in the age-matched general population in Singapore , 48. SecIn conclusion, our results showed that the Recalibrated Pooled KFRE SEA equation is an excellent predictive tool and performed better in terms of having a lower Brier score, less bias and improved precision than existing KFRE for identifying patients with CKD at risk for progression to ESKD in a primary care setting in SEA. Our findings suggest that implementation of the equation using 5-year thresholds > 10–16% to guide dialysis planning and 2-year threshold > 45% to guide nephrologist referral would facilitate more efficient and accurate risk stratification of patients at high risk of ESKD. Future studies are warranted to validate our findings, evaluate the clinical and cost effectiveness of a CKD model of care that integrates EHR and the KFRE in primary care settings serving Asians as well as globally.Additional file 1: Figure S1. Existing and recalibrated Kidney Failure Risk Equation (KFRE) for predicting 5-year risk of end-stage kidney disease among patients with chronic kidney disease stage 3–5. The figure shows the existing and recalibrated KFREs for predicting 5-year risk of end-stage kidney disease among patients with chronic kidney disease stage 3–5.Additional file 2 :Figure S2. Existing and recalibrated Kidney Failure Risk Equation (KFRE) for predicting 2-year risk of end-stage kidney disease among patients with chronic kidney disease stage 3–5. The figure shows the existing and recalibrated KFREs for predicting 2-year risk of end-stage kidney disease among patients with chronic kidney disease stage 3–5.Additional file 3: Figure S3. Calibration  plots of Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) with different constants for 5-year and 2-year risks of end-stage kidney disease. The figure shows the Brier score, bias and precision associated with different Recalibrated Pooled KFRE SEA constants at A) 5-year and B) 2-year risks of end-stage kidney disease to evaluate how closely the predicted risks agree with the observed risks.Additional file 4: Table S1. Baseline characteristics of patients with chronic kidney disease stage 3–5 with 2-year follow-up. The table shows baseline characteristics of patients with chronic kidney disease stage 3–5 included in the cohort with 2-year follow-up.Additional file 5: Figure S4. Observed risk versus predicted probability of end-stage kidney disease using the Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) at five and 2 years. The predicted and observed end-stage kidney disease probability estimates represent the mean values of predicted risk and observed probabilities in the risk categories according to the Recalibrated Pooled KFRE SEA risks at A) 5-year and B) 2-year risks of end-stage kidney disease.Additional file 6: Figure S5. Area under receiver operating characteristic curves of the Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) for predicting the 5- and 2-year risks of onset of end-stage kidney disease. The figure shows the Recalibrated Pooled KFRE SEA equations and eGFR receiver operating characteristic curves for predicting the A) 5-year and B) 2-year risks of end-stage kidney disease among patients with chronic kidney disease. Additional file 7: Table S2. Reclassification of 5-year risk of end-stage kidney disease onset among chronic kidney disease patients using the Recalibrated Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) equation thresholds at 10 and 16% compared to estimated glomerular filtration rate 30, 40 and 45 mL/min/1.73m2. The table shows the net reclassification improvement of the Recalibrated Pooled KFRE SEA equation threshold at 10 and 16% compared to estimated glomerular filtration rate 30, 40 and 45 mL/min/1.73m2 for predicting the 5-year risk of end-stage kidney disease among patients with chronic kidney disease.Additional file 8: Table S3. Reclassification of 2-year risk of end-stage kidney disease onset among chronic kidney disease patients using the Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) equation threshold at 45% compared to estimated glomerular filtration rate 20 and 18.8 mL/min/1.73m2. The table shows the net reclassification improvement of the Recalibrated Pooled KFRE SEA equation threshold at 45% compared to estimated glomerular filtration rate 20 and 18.8 mL/min/1.73m2 for predicting the 2-year risk of end-stage kidney disease among patients with chronic kidney disease.Additional file 9: Figure S6. Stratified analyses of area under receiver operating characteristic curves of the Pooled Kidney Failure Risk Equation Southeast Asia (KFRE SEA) for predicting the 5-year and 2-year risks of end-stage kidney disease. The figure shows stratified analyses of area under receiver operating characteristic curves and 95% confidence interval of the Recalibrated Pooled KFRE SEA equations for predicting the A) 5-year and B) 2-year risk of onset of end-stage kidney disease.


The aim of the study was to report the implementation of a functional networkfor the early diagnosis of chronic kidney disease (CKD) in patients withrisk factors and the coordinated work between primary and specialized carein social security in Perú.A cross-sectional analysis of the data of patients evaluated in a healthnetwork in the city of Lima (2013 to 2016), older than 18 years, with riskfactors for CKD, evaluated with serum creatinine and creatine albumin ratioin random urine (ACR). A multivariate logistic regression analysis wasperformed to evaluate the factors associated with the finding of CKD.The implementation included training in renal health, installation of adigital database, organization of laboratories, and empowerment of primarycare. We evaluated 42,746 patients of which 41.8% were men, with median age69.2 years. The most frequent cause of detection was hypertension (HBP):23,921 (55.9%). The prevalence of CKD was 12,132 (28.4%), the most frequentstage of CKD was 3a: 4735 (39.0%). Of the total, 6214 (14.5%) patients hadmicroalbuminuria and 1335 (3.1%), macroalbuminuria. The risk of CKDincreased 2.5 times (95% CI: 2.3-2.7) in patients with diabetes (DM) andHBP, in men  and as age increased . The identification of the disease in the primarycare setting is 60% less likely than in specialized care.One of every four patients are diagnosed with CKD, and the simultaneousdiagnosis of DM and HBP and old age are the most important factors. Chronic kidney disease (CKD) is a public health problem. It is associated to acardiovascular mortality risk of up to 8 to 10 times greater compared to the generalpopulation. Such risk increases with an associated reduction of the glomerularfiltration rate (GFR)In Peru, throughout the last decades, there has been a demographic and epidemiologictransition of the general population due to the increase of life expectancy and thegreater prevalence of cardiovascular risk factors , obesity and dyslipidemia), leading to a greater risk of the elderlyto suffer from CKDFurthermore, in recent years, the number of patients who enter renal replacementtherapy or arrive with late stages of kidney disease to nephrology services hasincreased. In a narrative review of CKD in Peru, Herrera et al. outline that thediagnosis and management of this condition is deficientAs CKD frequently develops asymptomatically, adequate assessment of renal function isessential. Early identification of patients with kidney failure allows prompttreatment to stop the progression of kidney damage, managing to modify theassociated risk factors that contribute to raise the morbidity in thesepatientsAlthough timely intervention of specialists is needed to improve the health ofpatients with CKD, it is also essential to avoid unnecessary referrals that coulddeplete the resources of the healthcare systemTherefore, a model of care with a structured program is required where both theprimary healthcare physician and the specialist work together in the detection andmanagement of CKD. In such model, the nephrologist intervenes in the directmanagement of patients with advanced stages of the disease and in the training ofprimary healthcare personnel for the supportive care of the renal patient.Simultaneously, the primary healthcare physician participates in the screening andmanagement of patients with early stages of kidney disease.This study reports the results from the largest healthcare network in Peru, theRebagliati health network located in Lima, which serves 23% of the population thathas social security in Peru (30% of the Peruvian population). It provides coverageto people with stable work and to retired people; generally the patients who arecared for are old and with multiple pathologies.A functional renal network was implemented, which included 14 primary care centersand two hospitals that are specialized in renal care. One of them is a hospital ofhigh complexity and a national reference. A multidisciplinary renal healthcare teamwas established in each hospital .The healthcare network was subdivided into 4 territorial micro-networks, which wereled by two nephrologists responsible for the on-site training of personnel in thediagnosis and management of CKD, as well as the registration of patients and in thereferral and cross-referral criteria between healthcare facilities. Fourlaboratories were designated for the standardized processing of screening tests:creatinine blood test and the random albumin-creatinine ratio (ACR). Likewise, eachcenter in the network had a software for the registration and follow-up of thepatients evaluated. The management of diagnosed patients, after the selection wassupervised by primary care for stages 1 to 3a and specialized care for stages 3b to5. After each evaluation, a digital record was made. We have summarized theimplementation strategy of an early detection model of CKD in The study was reviewed and approved by the Ethics Committee of the Hospital NacionalEdgardo Rebagliati Martins, Lima Peru.A retrospective secondary analysis of the database of electronic medical records ofpatients treated in outpatient renal health services of the Rebagliati healthnetwork between January 1, 2013 and November 30, 2016 was performed. The dataincluded patients over 18 years of age, of both sexes, with risk factors for CKD: DMand / or HBP and / or over 55 years of age, who had laboratory results of the bloodcreatinine test and ACR as part of the evaluation of the ERC.During the study period, patients were evaluated with a peripheral blood sample afteran 8-hour fast. Serum creatinine concentrations were determined by the compensatedJaffe creatinine method (Roche Diagnostics) that has calibration traceable to anIDMS reference measurement procedure. Creatinine values were expressed in mg/dL. Allthe patients left their first morning urine in the different healthcare centers andthe samples were sent to the designated laboratories. After centrifuging, thesamples were processed in an automated modular biochemistry analyzer  with albumin and creatinine reagents (Roche Diagnostics) for thequantitative determination of these analytes in urine. The results obtained werevalidated and entered into the database.2 and/or thepresence of a renal impairment marker (ACR>30 mg/g), independently of theunderlying cause of CKD, for a duration longer than 3 months. The estimatedglomerular filtration rate (eGFR) was calculated with the equation MDRD-4 fromthe Modification of Diet in Renal Disease study: eGFR = 186 × Creatinine- 1.154 × (Age) - 0.203 × (mL/min/1.73m2)Chronic kidney disease (CKD): according to the definition of the National KidneyFoundation - Kidney Disease Outcomes Quality Initiative (US NKF-KDOQI), CKD isdiagnosed when the patient meets any of the following criteria: decreased renalfunction expressed by a GFR < 60 mL/min/1.73 mRenal impairment marker (ACR): Results from the division of albumin by creatininemeasured in urine expressed in mg/g was considered as a marker for this study.According to the Kidney Disease: Improving Global Outcomes (KDIGO) 2012 clinicalpractice guideline, kidney damage can be classified as follows: A1: ACR < 30mg/g , A2: ACR between 30-300 mg/g (moderatelyincreased), A3: ACR > 300 mg/g (severely increased). The combination of bothdiagnostic criteria allows classifying CKD in 5 stages from lower to higherfunctional compromiseWe defined a patient with DM as one who previously had this diagnosis, has aglycosylated hemoglobin (HbA1c) level of 6.5% or higher, or with a fastingplasma glucose > 126 mg/dL or a random plasma glucose test > 200 mg/dL, orthose who were taking antidiabetic medications. A patient with HBP was definedas the one who previously had this diagnosis, has a blood pressure > 140/90mmHg, and those who were taking antihypertensive medication.p value < 0.20 in the bivariate analysis  and the ones that were considered biologically relevant. A value ofp < 0.05 was considered statistically significant. Thestatistical analyzes were performed using STATA version 13 .The Mann Whitney U test was applied to compare continuous variables and thechi-square test was used for categorical variables. The continuous variables arepresented as median and interquartile range (IQR) since they had skeweddistribution. The categorical variables are presented as frequencies andpercentages. The odds ratio (OR) and the 95% confidence interval (95%CI) werecalculated with multivariate models to quantify the association between chronickidney disease and potential predictor variables . The full model included variables thathad a In the study period, 50,285 patients were evaluated; 12 patients were excludedfrom the analysis because they were under 18 years old and 7,527 patientsbecause their complete data was not available. The final sample included 42,746patients.The demographic, clinical, and laboratory parameters of the population aredetailed in The CKD stage most frequently found in patients at the time of diagnosis was 3a:4,735 (39%). When evaluating the ACR laboratory results, 6,214 (14.5%) patientspresented moderate increase (A2) and 1,335 (3.1%) severe increase (A3). When theGFR and ACR results were interpreted to establish CKD staging and prognosis,1,478 (12.2%) patients had a higher risk of progression; these patients includedthose with advanced CKD and those with high levels of albuminuria .A positive correlation was observed between CKD and male population ; the risk raised as the age increased: approaching a risk of 2.7times (95%CI: 2.5-2.8) in patients older than 77 years. Likewise, havingdiabetes and hypertension increased the risk of CKD while there was a 60% lower probability of finding patients with CKD in primarycare than in specialized care  .Our study describes the results of the implementation of a CKD detection programbased on 4 fundamental pillars: constant training in renal health topics for primarycare professionals led by nephrologists, installation of a database that helps inthe search and follow-up of patients, implementation of laboratories for sampling,and above all, cooperative work between primary and specialized care. Our resultsconfirm that advanced age and comorbidities such as diabetes and hypertension arefactors that increase the risk of CKD.In Latin America, few countries have national programs to prevent CKD. According toCusumano's report in 2008, only Brazil, Cuba, Uruguay, Venezuela, and Peru haveinitiated such programs2The prevalence of CKD in the general population varies according to the geographicalarea between 8 and 13%This was also reported in a study conducted in the primary care setting of the socialsecurity healthcare system in Peru, concluding that 24.4% of diabetic patients and20.2% of hypertensive patients evaluated with GFR  and 24-hoururine protein test presented CKDRegarding CKD in hypertension, a study conducted by primary care physicians in Spainreports that 53.9% of patients with GFR< 60 mL/min have HBP2 was 37.8% between 1999 and 20042 per year after the age of30 years in healthy peopleThe median age of our patients with CKD was 73 years. In the NHANES report, theprevalence of CKD in patients older than 70 years with a GFR below 60mL/min/1.73mThe percentage of the different kidney damage classifications established by ACRresults is similar in all the studies reviewed. In a Korean studyFigueroa et al. evaluated microalbuminuria with ACR results in patients older than 55years with risk factors from the social security healthcare system in Peru,detecting A2 in 17.9% and A3 in 5.4%When evaluating the different stages of CKD in our population, we found that stages 1to 3A (GFR > 45 mL/min) constituted 82.6% of cases, which should be evaluated andfollowed-up in primary care centers. However, when evaluating each stageindependently, the most frequent was 3A in 39%, a result that matches the resultspublished by Benghanem et al. in Morocco who found that 3A is the most prevalent CKDstage of its study population: 40.2%2 and an ACR > 30 mg/g independently predict themortality risk and cardiovascular events that can be explained by endothelialdysfunction, bone mineral alteration, inflammation, and anemiaAn important aspect to consider in CKD is that a GFR below 60mL/min/1.73mThe protective factor of identifying the disease at the first level of care makesearly intervention necessary, reinforcing the need for a shared work between primaryand specialized care and the creation of renal health networks that ensure patientcare at any stage of sickness.As Cusumano statesA restriction to achieve this is the lack of public policies that encourage healthylifestyles in the general population and that now medical practice programs aremainly focused on treatment, with emphasis on dialysis , dismissing primary and secondary prevention programs. There are alsostructural and organizational limitations of the healthcare system for the generaland vulnerable populations, and it has been demonstrated that access barriers tohealthcare services interfere with quality care and limit the clinical protection ofpatients, increasing social and health inequityThe main strength of our work is its representativeness because it has been carriedout in the largest healthcare network in the country, which has allowed identifyingpatients with a higher risk of kidney disease. The results contribute with thedesign of strategies focused on this subgroup, especially those based on the sharedwork of primary and specialized care, achieving the empowerment of primary carephysicians in renal health topics and allowing the efficient use of specializedservices.This study also has some limitations. The underreporting of data might have occurred,because some professionals were not yet aware of the digital filling of clinicalinformation. Moreover, inadequate referral to the nephrologist and loss of patientsduring follow-up were considered study limitations.CKD in at-risk population affects 1 in every 4 patients evaluated. It is morecommonly found in early stages, and age and simultaneously having DM andhypertension increase the risk. The diagnosis of CKD in primary care contributeswith its early identification.


Supplemental Digital Content is available in the text. Ticagrelor has superior efficacy to clopidogrel in the management of acute coronary syndromes but has not been assessed in patients undergoing percutaneous coronary intervention for stable coronary artery disease. We compared the pharmacodynamic effects of ticagrelor and clopidogrel in this stable population.One hundred eighty aspirin-treated stable coronary artery disease patients, who were planned to undergo elective percutaneous coronary intervention in a single center, were randomized 1:1:1 to either a standard clopidogrel regimen or 1 of 2 regimens of ticagrelor, either 90 mg (T90) or 60 mg twice daily (T60), both with a 180 mg loading dose. Cellular adenosine uptake was assessed, at the time of the procedure and pre- and postdose at 1 month, by adding adenosine 1 µmol/L to aliquots of anticoagulated whole blood and mixing with a stop solution at 0, 15, 30, and 60 seconds, then measuring residual plasma adenosine concentration by high-performance liquid chromatography. Systemic plasma adenosine concentration and platelet reactivity were assessed at the same timepoints. High-sensitivity troponin T was measured pre- and 18 to 24 hours postpercutaneous coronary intervention.P=0.37). Similarly, no effect of ticagrelor on in vitro adenosine uptake was seen at other timepoints, nor was plasma adenosine concentration affected . Both maintenance doses of ticagrelor achieved more potent and consistent platelet inhibition than clopidogrel . High platelet reactivity was markedly less with both T60 and T90 compared with clopidogrel . Median (interquartile range) high-sensitivity troponin T increased 16.9 (6.5–46.9) ng/L for clopidogrel, 22.4 (5.5–53.8) ng/L for T60, and 17.7 (8.1–43.5) ng/L for T90 (P=0.95). There was a trend toward less dyspnea with T60 versus T90 .One hundred seventy-four patients underwent an invasive procedure, of whom 162 received percutaneous coronary intervention . No effect on in vitro adenosine uptake was seen postdose at 1 month for either ticagrelor dose compared with clopidogrel (residual adenosine at 15 seconds, mean±SD: clopidogrel 0.274±0.101 µmol/L; T90 0.278±0.134 µmol/L; T60 0.288±0.149 µmol/L; Maintenance therapy with T60 or T90 had no detectable effect on cellular adenosine uptake at 1 month, nor was there any effect on systemic plasma adenosine levels. Both regimens of ticagrelor achieved greater and more consistent platelet inhibition than clopidogrel but did not appear to affect troponin release after percutaneous coronary intervention.https://www.clinicaltrials.gov. Unique identifier: NCT02327624.URL:  Ticagrelor does not significantly impair adenosine uptake or increase circulating adenosine levels in patients with stable coronary artery disease.Ticagrelor 60 mg or 90 mg twice daily provides greater and more consistent platelet inhibition than clopidogrel in stable coronary artery disease patients undergoing elective percutaneous coronary intervention.12 inhibition did not modify troponin release related to percutaneous coronary intervention.More potent platelet P2YFurther studies of ticagrelor 60 mg twice daily are warranted in stable coronary artery disease patients undergoing percutaneous coronary intervention.Asymptomatic troponin release may not be a suitable end point for assessing the impact of greater platelet inhibition in stable coronary artery disease patients undergoing percutaneous coronary intervention.1301Editorial, see p 12 receptor antagonist is the standard therapy for patients undergoing percutaneous coronary intervention (PCI). Three oral platelet P2Y12 receptor antagonists are currently available: the thienopyridines clopidogrel and prasugrel, and the nonthienopyridine, reversibly binding drug ticagrelor.4 In the absence of contraindications or concurrent oral anticoagulant therapy, ticagrelor is recommended in preference to clopidogrel for patients with acute coronary syndromes, including those managed with PCI, but it has not been assessed in patients undergoing PCI for stable coronary artery disease (CAD).3 Similarly, prasugrel is recommended in preference to clopidogrel for acute coronary syndrome patients managed with PCI, but is not licensed for use in stable CAD.3 Consequently, aspirin and clopidogrel remain the predominant dual antiplatelet therapy strategy in stable CAD patients undergoing PCI.Dual antiplatelet therapy with aspirin and an oral platelet P2Y12 receptor, blocking the binding of ADP to this receptor.5 The efficacy of clopidogrel is limited in some individuals due to poor efficiency of active metabolite formation and poor pharmacodynamic response has been associated with increased risk of stent thrombosis in clopidogrel-treated patients.7Thienopyridines, such as clopidogrel, are prodrugs that require hepatic metabolism to generate active metabolites that bind irreversibly to the platelet P2Y9 Ticagrelor achieves a consistent high level of platelet P2Y12 inhibition following a loading dose , as well as during maintenance therapy with either 90 mg or 60 mg BID in patients with prior MI.9 Ticagrelor and AR-C124910XX also have weak inhibitory effects on cellular adenosine uptake via ENT-1 (equilibrative nucleoside transporter 1), although the clinical significance of this effect remains uncertain.14 The effects of ticagrelor 60 mg BID on adenosine metabolism have not been previously reported. In the STEEL-PCI study , we assessed and compared the effects of ticagrelor and clopidogrel on cellular adenosine uptake, as well as platelet reactivity in stable CAD patients undergoing PCI.Ticagrelor is not a prodrug but does have an active metabolite, AR-C124910XX, that is equipotent to ticagrelor and contributes approximately 30% of the total inhibitory effect.The data, analytic methods, and study materials will not be made available to other researchers for purposes of reproducing the results or replicating the procedure.online-only Data Supplement. The study was performed according to a protocol approved by the National Research Ethics Service and regulatory authorities. Aspirin-treated patients who provided informed consent were randomized in a 1:1:1 fashion to receive open-label treatment with a 180 mg loading dose of ticagrelor at 2 hours pre-PCI, followed by either 60 mg BID or 90 mg BID for 1 month or a standard loading regimen of clopidogrel (600 mg at least 4 hours prior to procedure or maintenance therapy with 75 mg for at least 5 days), followed by 75 mg QD for 1 month . All patients had had previous coronary angiography and were planned to undergo PCI. Other inclusion as well as exclusion criteria are shown in the online-only Data Supplement).For adenosine reuptake measurements, blood was collected into a standard ethylenediaminetetraacetic acid tube and then aliquots pipetted into tubes containing adenosine . Uptake of adenosine was halted by the addition of a cold pharmacological stop solution (2 parts blood:1 part stop solution) at 0, 15, 30, or 60 seconds after mixing blood with the adenosine. The stop solution was composed of dipyridamole 40 µmol/L, disodium ethylenediaminetetraacetic acid 13.2 mmol/L, erythro-9-(2-hydroxy-3-nonyl)adenine 50 µmol/L, α,β-methylene adenosine 5’-diphosphate 200 µmol/L, iodotubercidin 50 µmol/L, and p-nitrobenzylthioinosine 40 µmol/L in 0.9% wt/vol sodium chloride. Adenosine concentration was measured using high-performance liquid chromatography . P2Y12 reaction units (PRU) and VerifyNow percentage inhibition (estimated using the Base channel result as 100% response) were recorded.Whole blood was collected into 2-mL Greiner Bio-One citrate tubes and gently mixed before analysis after 20 minutes using the VerifyNow P2YLight transmission aggregometry (LTA) was performed using a PAP8 aggregometer  with ADP 20 μmol/L as the agonist. Maximum percentage LTA responses were recorded.High-sensitivity troponin T was determined in serum samples  before PCI and the morning after PCI.17Plasma derived from blood anticoagulated with lithium heparin was stored at –80°C prior to analysis. Plasma concentrations of ticagrelor and AR-C124910XX were determined using liquid chromatography with tandem mass spectrometry by York Bioanalytical Solutions .CYP2C19, CY3A43, UGT2B7, and SLC01B1 (see the online-only Data Supplement).DNA was extracted from whole blood and analyzed for relevant genetic variants of 18; and (2) the assumption that the effects of ticagrelor 60 mg would yield levels between those with ticagrelor 90 mg and clopidogrel. Data on 42 patients per group were required in each group to provide >90% power to detect a 0.05 µmol/L higher mean residual adenosine level in the ticagrelor 60 mg group compared with the clopidogrel group, with a significance threshold of 0.05 and assuming a common SD of 0.06 µmol/L, and >99% power to detect a similar difference between the ticagrelor 90 mg and clopidogrel groups to that previously reported. Sixty patients were, therefore, required in each group to allow for 30% dropout or sample failure at 1 month. Secondary endpoints were plasma adenosine concentration, platelet function measurements, and the PCI-induced troponin release (determined as increase from pre-PCI to post-PCI). Based on our previous work,9 the proposed sample size provided >90% power to detect expected differences in platelet aggregation, assessed by either VerifyNow P2Y12 assay or LTA, between ticagrelor and clopidogrel, with a significance threshold of 0.01 , allowing for 30% dropout or sample failure at 1 month.The primary end point of the study was in vitro adenosine uptake postmaintenance dose at 1 month, measured as residual adenosine concentration at 15 seconds after ex vivo addition of adenosine. The sample size was based on (1) our preliminary in vitro studies of adenosine uptake indicating 15 seconds as the optimal time for assessing residual adenosine concentration, and previous data indicating an estimated mean (±SD) residual adenosine concentration at 15 seconds postmixing in the adenosine uptake assay of 0.80±0.051 µmol/L for the ticagrelor 90 mg group and 0.45±0.068 µmol/L for clopidogrel9 MI was defined according to the Third Universal Definition.19 Bleeding events were defined according to the PLATO study (Platelet Inhibition and Patient Outcomes) criteria.20Data were analyzed using SAS version 9.3  and expressed as mean and SD for normally distributed data or median and interquartile range for nonparametric data. Continuous data were compared using the Kruskal-Wallis test, where appropriate using the Mann-Whitney test for pairwise comparisons, as indicated in Results. Categorical variables were compared using the chi-square test or Fisher exact test, as indicated in Results. High platelet reactivity was defined as VerifyNow PRU >208 or LTA response >59%.online-only Data Supplement. The demographic characteristics, cardiovascular risk factors, and concomitant medications were well matched between the groups at randomization and subsequent timepoints, as were the procedural characteristics for those proceeding with PCI (Table Tables I and II in the online-only Data Supplement). At the time of their procedure, 100% patients were receiving aspirin 75 mg daily and continued on this for the duration of the study.One hundred eighty patients were recruited to the study Figure . Sixty pFigure I in the online-only Data Supplement). Similarly, there was no impact of ticagrelor at any time point on plasma adenosine level  for the 60 mg versus 90 mg ticagrelor doses, and postdose values were 34±30 versus 24±21 (P=0.09), respectively; corresponding PRU values for clopidogrel-treated patients were 181±44 predose and 159±57 postdose . The mean LTA responses were also significantly lower in the ticagrelor groups compared with the clopidogrel group, both at the time of PCI and at 1 month  at the time of PCI  according to LTA responses compared to greater proportions in the clopidogrel group (>30%) at each timepoint Figure .P=0.95, Kruskal-Wallis test).There were no MIs, strokes, or cardiac deaths in any of the groups at 30 days. There was only 1 death, which occurred as a result of sepsis following mesenteric infarction that did not appear to be related to the PCI procedure. There was no effect of the higher levels of platelet inhibition with ticagrelor on PCI-induced increase in high-sensitivity troponin T: median (interquartile range) increases the morning after PCI were 16.9 (6.5–46.9) ng/L for the clopidogrel group, 22.4 (5.5–53.8) ng/L for the ticagrelor 60 mg group, and 17.7 (8.1–43.5) ng/L for the ticagrelor 90 mg group (P=0.09) (Table III in the online-only Data Supplement). Two patients (3.6%) in the ticagrelor 60 mg group and 3 patients (5.2%) in the ticagrelor 90 mg group stopped study medication prematurely due to adverse effects. There was no reported dyspnea in the clopidogrel group, and no patients stopped clopidogrel prematurely due to adverse effects. There were no PLATO-defined major or minor bleeds and no major adverse cardiac events or stent thrombosis events in any of the treatment groups.The tolerability of the ticagrelor 60 mg BID dose appeared slightly better than the 90 mg BID dose due to less frequent dyspnea events in the 60 mg group . After 1 month maintenance therapy with either ticagrelor 60 mg or ticagrelor 90 mg BID, predose mean levels of ticagrelor were 278±217 and 365±189 ng/mL, respectively, and predose mean levels of AR-C124910XX were 97±55 and 127±73 ng/mL, respectively. Postdose mean levels of ticagrelor were 510±281 and 776±347 ng/mL, and mean levels of AR-C124910XX were 135±69 and 199±96 ng/mL, respectively .The mean plasma levels of ticagrelor and AR-C124910XX following ticagrelor 180 mg loading dose were 1109±549 and 223±121 ng/mL, respectively . The other genetic variants studied did not significantly influence the pharmacodynamic and pharmacokinetic results (Tables VI through XI in the online-only Data Supplement).The ticagrelor loading dose and both ticagrelor maintenance doses achieved greater platelet inhibition than clopidogrel in those who either did or did not carry CYP2C19 genotyping. Our data are broadly consistent with previously reported data on ticagrelor 90 mg and 60 mg twice daily in patients with prior MI.21 Our finding of significant difference in predose platelet reactivity during maintenance therapy in the 2 ticagrelor groups, in contrast to lack of significance of this comparison in the PEGASUS-TIMI 54 platelet function substudy ,9 likely reflects small sample sizes in both studies, limiting the power to detect such a difference. Dyspnea was more frequent in the ticagrelor groups, and this is a well-characterized adverse effect of ticagrelor that is usually mild or moderate in severity, as confirmed here.24 The lower rates of dyspnea in the ticagrelor 60 mg group, combined with the reliable P2Y12 inhibition, as also previously demonstrated in the PEGASUS-TIMI 54 study,24 favor this dose for further exploration in clinical outcomes studies.In this study, we compared the pharmacodynamic effects of ticagrelor and clopidogrel, obtaining data on the 60 mg BID dose of ticagrelor for the first time in stable CAD patients undergoing PCI and collecting preliminary efficacy, safety, and tolerability data on the 2 doses of ticagrelor in this setting. Consistent with previous comparisons of the ticagrelor 180 mg loading dose and 90 mg twice-daily maintenance dose with standard regimens of clopidogrel in other clinical settings, we confirmed that the ticagrelor loading dose and maintenance doses achieved greater and more consistent levels of platelet inhibition compared to standard regimens of clopidogrel in stable CAD patients at the time of, and 1 month after, PCI. Of note, we show that the ticagrelor 60 mg twice-daily maintenance dose provides much more consistent platelet inhibition than clopidogrel, even in those with normal CYP2C19 activity as predicted by 25 we found no evidence of any effect of the ticagrelor regimens on cellular adenosine uptake or plasma adenosine concentration. The reasons for this are unclear since our data show clearly that the assay assessed adenosine uptake over 1 minute in whole blood samples, with the expected baseline levels of adenosine after in vitro addition of 1 µmol/L (indicating efficacy of the stop solution in preventing further adenosine uptake) and almost complete adenosine uptake at 1 minute (indicating efficacy of the stop solution in preventing adenosine generation). Our stop solution for adenosine metabolism included additional inhibitors to those used by Bonello et al,18 including p-nitrobenzylthioinosine as an additional inhibitor of adenosine uptake and iodotubercidin as a potent adenosine kinase inhibitor, and therefore may have been more effective. In agreement with our findings, a recent study in healthy volunteers found no impact of ticagrelor on plasma adenosine level.26 Furthermore, using the same methodology, we found no impact of ticagrelor on plasma adenosine concentration in acute coronary syndrome patients awaiting coronary artery bypass graft surgery, suggesting that the nature of the patient population in our current study was not a determinant of the findings.27 In vitro studies predict little effect of ticagrelor on adenosine uptake at therapeutic concentrations due to high levels of plasma protein binding that limit the free ticagrelor available to bind to ENT-1.28 On the other hand, an effect of ticagrelor on adenosine uptake is more clearly seen at approximately therapeutic concentrations in the absence of plasma proteins.29 Since ticagrelor has been shown to induce a leftward shift in the dose-response curves for intravenous adenosine in studies of coronary blood flow responses and dyspnea severity, it remains likely that ticagrelor has an impact on the kinetics of adenosine uptake in vivo at the tissue level, such as in myocardium, that is not detected by the currently available blood assays, and more work is required to assess this.30Contrary to some previous published studies,12 inhibition in a low-risk population. This observation is consistent with a previously reported small elective PCI study,31 but contrasts with another small study that demonstrated a reduced rate of MI with ticagrelor compared to clopidogrel.32 Larger clinical outcomes studies are in progress that will provide more definitive data on this comparison (NCT02617290 and NCT02548611).There were substantial numbers of patients with asymptomatic rises in troponin after PCI, but no evidence that ticagrelor was more effective than clopidogrel in attenuating troponin release, suggesting that the extent of myocardial injury induced by PCI is not usually sensitive to levels of platelet P2YThis study was limited by a small sample size for assessing efficacy, safety, and tolerability, and a larger study is required to establish the benefits and risks of ticagrelor in stable CAD patients undergoing PCI. Our study simply provides pilot data for planning such a study. Only the impacts of ticagrelor on adenosine uptake in whole blood and circulating adenosine levels were assessed, not the impact of ticagrelor on tissue-level adenosine metabolism. The study was also not well powered for comparing the pharmacodynamic effects of the 2 maintenance doses of ticagrelor, although some significance was seen in predose levels of platelet reactivity suggesting that the 90 mg BID dose may have slightly greater consistency of effect than the 60 mg BID dose.In conclusion, ticagrelor 60 mg and 90 mg BID regimens both achieved greater and more consistent platelet inhibition than standard clopidogrel therapy, but had no detectable impact on cellular adenosine uptake or circulating plasma adenosine concentration in stable CAD patients undergoing PCI. Further work is warranted to characterize the efficacy and safety of ticagrelor in this clinical setting.Data Monitoring Committee Robert G. Wilcox (chair), University of Nottingham John T. Walsh, Nottingham University Hospitals NHS Trust William Smith, Nottingham University Hospitals NHS Trust Allan Skene, retiredThe authors are grateful to Drs Matthew Larman and Sven Nylander for their support. We also thank Drs Nana Theodorou and Erica Wallis, Clinical Research Office, Sheffield Teaching Hospitals National Health Service Foundation Trust, for their support.This study was funded by an investigator-initiated grant from AstraZeneca. The study was supported by the National Institute for Health Research award to the Sheffield National Institute for Health Research Clinical Research Facility. The views expressed are those of the authors and not necessarily those of the National Health Service, the National Institute for Health Research, or the Department of Health.Dr Storey reports institutional research grants/support from AstraZeneca and PlaqueTec; consultancy fees from AstraZeneca, Actelion, Avacta, Bayer, Bristol-Myers Squibb/Pfizer, Idorsia, Novartis, PlaqueTec, and The Medicines Company; and speaker fees from AstraZeneca. The other authors report no conflicts of interest.