Social anxiety disorder (SAD) symptoms are maintained by cognitive biases, which are overestimations of the severity and likelihood of negative social events (cost/probability biases), and by sensitivity to rewards and punishments that are determined according to behavioral inhibition/behavioral activation systems (BIS/BAS). Cost/probability biases might activate the behavioral immune system and exacerbate the avoidance of social events. Earlier studies have proposed that low BIS or high BAS decrease SAD symptoms; BIS/BAS may even change the effects of cognitive biases on SAD symptoms. Hence, the current study investigates the interaction effects of BIS/BAS and cost/probability biases on SAD symptoms.Seventy-six Japanese undergraduate students completed the Japanese version of the Liebowitz Social Anxiety Scale (LSAS), which comprises Fear and Avoidance subscales, the BIS/BAS Scale, and the Social Cost Probability Scale.p < 0.001; β = 0.33, p < 0.01) and LSAS-Avoidance . The interaction effect between cost bias and BAS was significant for LSAS-Avoidance . Simple slope analysis showed that the slope of cost bias was significant for low-BAS individuals  but not for high-BAS individuals . The interaction effect between probability bias and BAS was significant for LSAS-Avoidance  as well. Further, simple slope analysis revealed that the slope of probability bias was significant for low-BAS individuals  but not for high-BAS individuals .A multiple regression analysis was performed to examine whether cost/probability biases, BIS/BAS, and their interactions affected SAD symptoms; following this, the main effects of cost bias and BIS were determined for LSAS-Fear (β = 0.64, The study found interesting results with respect to the avoidance of social events. Low-BAS individuals with high cost or low probability biases regarding social events may have a tendency to avoid social events. In contrast, if high-BAS individuals overestimate the cost of social events or underestimate the probability of social events, their anticipation of rewards might prevent them from avoiding social events. Social anxiety disorder (SAD) is characterized by an excessive fear and avoidance of social situations where individuals feel scrutinized and fearful of being negatively evaluated by others . The 12-Cognitive bias is believed to play an important role in the maintenance of SAD symptoms e.g., . AccordiHowever, to date, the ways in which the above-mentioned factors  interact with one another to develop and maintain SAD symptoms remain unclear. p < 0.001) was lower than that of BIS on cognitive biases . In addition, the correlations between BAS and cognitive biases were weak . Furthermore, Hence, the current study investigates the interaction effects of the BIS/BAS and cost/probability biases on SAD symptoms. The results are expected to contribute to the development of SAD therapies tailored to individual characteristics. Accordingly, we conducted a cross-sectional study to assess BIS/BAS, cost/probability bias, and social anxiety and hypothesized that BIS was positively correlated with cost/probability bias and SAD symptoms. Further, we hypothesized that the coefficient of the interaction effects between BAS and cost bias and that between BAS and probability bias on SAD symptoms are negatively significant. Specifically, for low-BAS individuals, the higher cost/probability bias, the higher the SAD symptoms. Contrastingly, for high-BAS individuals, SAD symptoms do not increase even with an increase in cost/probability bias.Participants were 76 undergraduate students  of Waseda University, Saitama, Japan. Students were recruited from psychology classes. The inclusion criterion was: (a) being 20 years of age or older. Further, the exclusion criteria were as follows: (a) undergoing counseling, (b) being prescribed medication by a doctor, and (c) having ever continuously visited medical institutions offering psychiatric and psychosomatic medicine. The study did not have invasiveness. Participants were aged over 20 years. Therefore, we omitted the procedures for informed consent in accordance with the recommendations of the Ethical Guidelines for Medical and Health Research Involving Human Subjects. Instead, completion of the questionnaire was considered as informed consent. Further, we provided both verbal and written explanations of informed consent to potential participants based on the recommendations of the Ethical Guidelines for Medical and Health Research Involving Human Subjects. In particular, the questionnaire’s first page contained the following information for participants: the research objective, inclusion and exclusion criteria, consideration of questionnaire completion as the consent to participate, free and voluntary nature of survey participation, information that data will be processed statistically and participant information will be kept anonymous and confidential, and information that participation or non-participation is unrelated to the participants’ class evaluation.The participants completed the Japanese version of the Liebowitz Social Anxiety Scale (LSAS), which comprises Fear and Avoidance subscales, the BIS/BAS Scale, and the Social Cost Probability Scale (SCOP). The study was approved by the ethics committee of Waseda University.The LSAS, comprising 24 items rated on a scale of severity from 0 to 3, is a valid and reliable social anxiety measure . The LSAThe LSAS items are descriptions of various social events. Some sample items include “Calling in public” and “Expressing my opinion at a meeting.” For each Fear subscale item, the participants were required to rate the degree of fear on a four-point scale. Similarly, for each Avoidance subscale item, they were required to rate the degree of avoidance on a four-point scale.The SCOP is a 12-item scale of perceived cost/probability bias in social events, with response options ranging from 1 to 5. SCOP is a valid and reliable measure of cost/probability biases .The SCOP has items describing different social events and respondents’ cognition of cost bias in these social events. Some sample items are “I think that my opinion will be misunderstood if I express it in public” and “I think that I will be rejected when I talk with my friend.” To assess cost biases, participants were required to score the following question on a five-point scale: “To what extent does the following idea applies to each situation?” Further, to assess probability biases, the participants had to score the following question on a five-point scale: “To what extent do you think the following idea will come true in each situation?”Research has proved the validity and reliability of the BIS/BAS Scale, which comprises 20 items rated on a scale of severity from 1 to 4 . The JapPearson’s correlation coefficients were calculated to examine the associations between all the variables. After conducting bivariate analysis, we conducted a multiple regression analysis to examine whether cost/probability biases, BIS/BAS, and their interactions affected SAD symptoms. We used SPSS version 24.0 to analyze the data.n = 31), mild , moderate , and severe . Eighty-nine percent of the participants were rated as having mild or less than mild symptoms. In addition, the means and standard deviations of each of the descriptive variables were similar to those of earlier findings on healthy Japanese people , probability bias , and BIS . In addition, there were significant positive correlations between avoidance symptoms of social anxiety and cost bias , probability bias , and BIS . Moreover, there were significant positive correlations between BIS and cost bias , between BIS and probability bias , and between BIS and BAS .Pearson’s correlation analysis was applied to examine the associations among all the variables . The resp < 0.001; β = 0.33, p < 0.01) and LSAS-Avoidance . The results suggested that an increase in cost bias and BIS significantly increased SAD symptoms. Further, the interaction effect between cost/probability bias and BAS was not significant for LSAS-Fear , whereas that between cost bias and BAS was significant for LSAS-Avoidance . Simple slope analysis showed that the slope of cost bias was significant for low-BAS  but not high-BAS  individuals. Further, the results revealed that the combination of low BAS and high cost bias increased avoidance. The interaction effect between probability bias and BAS was significant for LSAS-Avoidance , as well. Further, simple slope analysis showed that the slope of probability bias was significant for low-BAS  but not high-BAS  individuals. The results showed that the combination of low BAS and low probability bias increased avoidance. A multiple regression analysis was conducted to examine whether cost/probability biases, BIS/BAS, and the interactions between these variables predicted SAD symptoms . AccordiThe current study examined the interaction effects between BIS/BAS and cost/probability biases on SAD symptoms. The results of Pearson’s correlation analyses revealed significant positive correlations between BIS and cost bias, probability bias, and SAD symptoms. Further, multiple regression analysis detected significant interaction effects between cost bias and BAS and between probability bias and BAS for avoidance of social events. Simple slope analysis revealed that the slope of cost/probability bias was significant for low-BAS but not high-BAS individuals. In particular, low-BAS individuals who estimate that there will be a high cost or low probability of social events tend to avoid them. On the other hand, even if high-BAS individuals overestimate the cost or probability of social events, the anticipation of positive outcome occurrence may supersede their tendency to avoid social events. These results were consistent with the first hypothesis that BIS is positively correlated with cost/probability bias and SAD symptoms. Further, the second hypothesis was that low-BAS individuals with high-cost/probability bias presented increased SAD symptoms. The results of the multiple regression analysis of avoidance of social events partially confirmed the second hypothesis, whereas high-BAS individuals did not experience increased SAD symptoms regardless of the degree of their cost/probability bias.Regarding the first hypothesis that BIS is positively correlated with cost/probability bias and SAD symptoms, the current results conform to the findings obtained by other researchers. BIS is proposed to trigger response to threatening stimuli or expectation of such stimuli. Thus, high BIS may cause cognitive biases such as negative belief and negative expectation in threatening situations  and highThe second hypothesis, that the coefficient of the interaction effects between BAS and cost bias and between BAS and probability bias on SAD symptoms is negatively significant, was confirmed only for cost bias on the avoidance symptoms of SAD. In addition, regarding probability bias, the results showed that a low probability bias might increase the avoidance symptoms of SAD; this result was inconsistent with our hypothesis and earlier reports e.g., .First, we consider the results on cost bias. BAS has been proposed to promote goal-oriented behavior . Based oSecond, the relationship between probability bias and avoidance of social events was inconsistent with the findings of earlier studies, according to which overestimating the likelihood of a social situation’s negative outcome would increase SAD symptoms . Since tRegarding why a difference was observed for avoidance but not fear, r = 0.12, p < 0.05) between the BIS and BAS. This weak correlation might be caused by the effect of spurious correlation. Because BIS and BAS were assumed to correlate positively with neuroticism, the partial correlation coefficient between BIS and BAS controlling neuroticism was calculated. Results showed that there was no significant partial correlation coefficient . Since the current study used the scale developed by In addition, the results of Pearson’s correlation analyses revealed significant positive correlations between BIS and BAS. Earlier studies have revealed that BIS and BAS are independent of each other . On the The current study has three main limitations. The first is our use of a student sample. We believe that future studies may benefit from replicating the findings using a clinical sample. Second, we did not conduct a social threat manipulation. This study found interesting results regarding avoidance of social events. If low-BAS individuals overestimate the cost or underestimate the probability of social events, they tend to avoid them. On the other hand, in the case of overestimation or underestimation by high-BAS individuals, their desire to receive rewards tends to supersede their tendency to avoid social events. Although this topic requires additional research, our findings imply that the cost/probability bias toward social events may be the mechanism through which BIS and BAS exert their influence on SAD symptoms. Future studies should examine the change in avoidance symptoms of SAD while addressing cost/probability bias.The datasets generated for this study are available on request to the corresponding author.This study was carried out in accordance with the recommendations of the Ethical Guidelines for Medical and Health Research Involving Human Subjects, Ministry of Education, Culture, Sports, Science and Technology and Ministry of Health, Labor and Welfare. The current study did not involve invasiveness. All the participants were over 20 years of age. Therefore, we omitted the procedures concerning informed consent in accordance with the recommendations of the Ethical Guidelines for Medical and Health Research Involving Human Subjects. Further, completion of the questionnaire was considered informed consent. We provided both verbal and written explanations on informed consent to potential participants based on the recommendations of the Ethical Guidelines for Medical and Health Research Involving Human Subjects. Further, the participants were informed about the study’s objectives, notified of the voluntary nature of participation, and assured of their data’s anonymity and confidentiality. The protocol was approved by the Research Ethics Committee of Waseda University.RI, NK, SY, and SS developed the research idea. RI, NK, SY, HI, and YT performed the data collection. RI performed the data analyses and wrote the first draft. All authors contributed to the revision of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Bile is a biological fluid synthesized in the liver, mainly constituted by bile acids and cholesterol, which functions as a biological detergent that emulsifies and solubilizes lipids, thereby playing an essential role in fat digestion. Besides, bile acids are important signaling molecules that regulate key functions at intestinal and systemic levels in the human body, affecting glucose and lipid metabolism, and immune homeostasis. Apart from this, due to their amphipathic nature, bile acids are toxic for bacterial cells and, thus, exert a strong selective pressure on the microbial populations inhabiting the human gut, decisively shaping the microbial profiles of our gut microbiota, which has been recognized as a metabolic organ playing a pivotal role in host health. Remarkably, bacteria in our gut also display a range of enzymatic activities capable of acting on bile acids and, to a lesser extent, cholesterol. These activities can have a direct impact on host physiology as they influence the composition of the intestinal and circulating bile acid pool in the host, affecting bile homeostasis. Given that bile acids are important signaling molecules in the human body, changes in the microbiota-residing bile biotransformation ability can significantly impact host physiology and health status. Elucidating ways to fine-tune microbiota-bile acids-host interplay are promising strategies to act on bile and cholesterol-related disorders. This manuscript summarizes the current knowledge on bile and cholesterol metabolism by intestinal bacteria, as well as its influence on host physiology, identifying knowledge gaps and opportunities to guide further advances in the field. The human gastrointestinal tract (GIT) is colonized by a vast array of microbes which dynamically interact with dietary and host-derived molecules in the intestinal lumen, significantly contributing to host physiology. Indeed, several animal and human studies have demonstrated that specific gut microbiota configurations contribute to inflammatory and metabolic diseases , althougBile acids are synthesized in hepatocytes from cholesterol and conjugated to glycine and taurine before being secreted into the small intestine with the bile flow, which plays a major role in fat emulsification and absorption. Bile composition depends on the diet and intrinsic characteristics of the individuals, but usually contains over 50% BAs, over 20% fatty acids and cholesterol, and lower amounts of other molecules such as bilirubin or phospholipids . During Bile acids and cholesterol reaching the large intestine dynamically interact with our gut microbes. Indeed, BAs strongly compromise bacterial survival in the GIT, thus gut microbes must have developed mechanisms to counteract bile toxicity . BesidesThe present minireview examines the current knowledge on the enzymatic activities of intestinal bacteria over BAs and cholesterol, and their implications in human physiology, with a particular emphasis on their impact on gastrointestinal disorders and aging-associated decline. Opportunities and limitations to translate this body of knowledge into novel microbiome-based applications for some of these diseases are also discussed.Cholesterol is a terpenoid lipid with a carbon skeleton formed by four fused alicyclic rings. It is an essential component of the mammalian cell membranes and precursor of steroid hormones, vitamin D, and primary BAs . FollowiThe metabolism of cholesterol by gut microbes has been described since the 30s  and has Several factors throughout life, including changes in diet or antibiotics consumption , have beBacteroides sp. strain D8  have been proposed , to dateThe metabolism of BAs by the gut microbiota has been known for decades, although its consequences on human health have only started to be considered , openingThe composition of the BAs pool in humans is determined by the enterohepatic cycle and the microbial metabolism of intestinal BAs. Briefly, the liver synthesizes two primary BAs from cholesterol, cholic acid and chenodeoxycholic acid, which are conjugated to either taurine or glycine before being poured into the bile flow. Conjugated BAs are the primary components of bile, which is stored in the gallbladder before being excreted into the small intestine during digestion. Over 95% of the BAs secreted in bile are reabsorbed in the terminal ileum, returning to the liver through the enterohepatic circulation, and only 5% reach the large intestine, being excreted in feces. In the large intestine, BAs can suffer several microbial-mediated transformations including deconjugation, carried out by bile salt hydrolases (BSHs) that hydrolyze the amide bond, and transformation of primary deconjugated BAs into secondary BAs mainly by a 7α-dehydroxylation . WhereasBacteroides, Clostridium, Lactobacillus, and Bifidobacterium, among others, being more diverse in members of the phylum Firmicutes , yielding lithocholic acid  and type-2 diabetes patients , which governs bile, glucose and lipid metabolism . Indeed,patients . Accordipatients , 2013. It health .The relation between diet, microbial metabolism of BAs and human disorders, including colorectal cancer risk (CRC), is further supported by the fact that dietary fat increases biliary hepatic synthesis and, thus, the quantity of BAs that reach the colon, providing substrate for the synthesis of secondary BAs. These have been described as proinflammatory  and theiBilophila species, and increased secondary BAs production , primary sclerosing cholangitis, steatosis and hepatic cancer – frequently associated with obesity – have been related to different intestinal microbial patterns . In someoduction . Additiooduction . Consequoduction , which gClostridium group, among which 7α-dehydroxylase activity is frequent  increased the plasma and liver cholesterol levels and reduced hepatic BAs synthesis . Also, tSince BAs are ligands of bile-responsive receptors involved in host metabolism, changes in BAs composition orchestrated by the intestinal microbiota activity, may affect their interaction with specific receptors, such as pregnane-activated receptor, vitamin D receptor, sphingosine-1-phosphate receptor, muscarinic receptor . Additioin vivo studies (Lactobacillus strain to mice fed high-fat diets (Lactobacillus strain significantly reduced cholesterol in hypercholesterolemic subjects (In light of the recently unearthed gut microbiota-BA-host signaling interactions, microbiota-based approaches, from probiotics to dietary interventions, may become novel strategies to manage specific diseases linked to BAs metabolism dysregulation, as suggested by some  studies . Most st studies  in assoc studies , changesat diets . Howeversubjects , althougSome probiotic interventions have also demonstrated their efficacy to ameliorate liver and inflammatory markers in models of NAFLD and IBD, although results are not yet conclusive . Besidesbsh encoding genes in the gut microbiota, and an increase in the representation of potential pathobiont species such as B. wadsworthia (Akkermansia muciniphila enrichment through administration of epigallocatechin-3-gallate prevented diet-induced obesity and regulated bile signaling (Diet is another factor known to affect the gut microbiota and the BAs host signature. For instance, in a dietary intervention study in humans, a diet rich in animal-based fats was associated with increased excretion of secondary BAs, in accordance with an increased overall expression of sworthia . Thus, dsworthia . Though ignaling , althougin vivo models or human trials, and exploiting microorganisms or activities with demonstrated capacity to specifically act on selected BAs, are necessary for aiding the development of novel microbiome-based approaches for disorders associated with BAs dysregulation.In summary, it has become increasingly clear that BAs exert a much wider range of biological activities than initially recognized and that BAs, gut microbiota and health status are closely linked and hold a yet- underexplored valuable potential to design novel diagnostic and therapeutic approaches based on specific gut microbiota activities. Elucidating the molecular mechanisms underlying the gut microbiota-BA-host health interplay will establish the basis to fully understand the gut microbiota potential to modulate bile metabolism and host health. Further studies using specifically designed AM, SD, and BS conceived and organized the manuscript. NM designed the figures. NM, LR, BS, AM, and SD contributed to the writing, critically reviewed the manuscript, and approved the final version of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The performance enhancing (ergogenic) placebo effect is elicited by an inert treatment and caused by positive affective appraisal of effort perception. Frontal alpha asymmetry (FAA) is a neurobiological correlate of positive affect. This study investigates, whether receiving an ergogenic placebo increases FAA and whether scores on the behavioral inhibition and activation system (BIS/BAS) scales affect this increase in FAA. Nineteen competitive male cyclists (37.26 ± 9.82 years) performed two maximum effort time trials. The first served as baseline for the second intervention time trial, where athletes received a placebo ergogenic aid or no treatment. We recorded FAA using EEG throughout all time trials and assessed BIS/BAS by questionnaire. There was a significant difference in change from baseline to intervention time trial in FAA during cycling in response to the placebo ergogenic aid compared to the control group. BIS, the BAS subscale Drive and the BAS-BIS difference score significantly co-varied with the change in FAA from baseline to intervention time trial in response to the placebo ergogenic aid. Administering a placebo ergogenic aid significantly influenced FAA during maximum effort cycling. Those athletes with a more pronounced goal seeking persistence and an overall dominance of the BAS over the BIS showed a significantly greater increase in FAA in response to a placebo ergogenic aid. A more pronounced BIS, however, seems to antagonize the increase in FAA associated with the ergogenic placebo response. Accordingly, the ergogenic placebo effect (EPE) is the performance enhancing effect elicited by a placebo ergogenic aid (PEA). More specifically, the EPE is operationalized as performance enhancement without the expected increase in perceived exertion3 or even a decrease in fatigue4. Since the perception of effort is an unpleasant sensation, we assume that the EPE is associated with more positive affect. Moreover, a PEA increases reward probability by inducing expectations of performance enhancement and therefore functions as a positive affective cue.The placebo effect is defined as “any improvement in a symptom or physiological condition of individuals following a placebo treatment”7 and carbohydrates8, and in running using sodium bicarbonate9 and a hypothetical new ergogenic aid10. In strength training, the EPE has been shown using anabolic steroids12, amino acids13 and caffeine14 in different compound and isolation movements such as bench press, leg extension and deadlift. A review of 12 studies found overall changes in performance ranging from −7.8% to +50.7% after ergogenic placebo interventions15. A meta-analysis of 14 studies reported small to moderate effects of placebo treatments in sports performance16. According to a recent survey based study of 79 elite athletes from different sports, 47% of elite athletes have experienced placebo effects first hand, the majority believe in the possible ergogenic effect of placebos (82%) and those with past placebo experiences were more likely to endorse a wider use of placebos in the sport setting than those without past placebo experiences17. Despite increasing interest in the brain mechanisms mediating the placebo response in motor performance20, to this day there is no study investigating cortical processes involved in the ergogenic placebo response (EPR) during high intensity endurance performance. This gap in research is caused by the fact, that most brain imagery methods are highly susceptible to artifacts due to movement and muscle contractions. However, technological developments in recent years have enabled the recording of cortical activation during endurance performance using active EEG electrodes, which amplify the electrical signals recorded from the scalp directly at the electrode, making it less susceptible to external electrical activity and movement artifacts22. Standardized test conditions on a bicycle ergometer further minimize the influence of artifacts and enable the recording of cortical parameters during exercise23. We therefore used EEG in this study of the EPR, as it allows the recording of brain activity during high intensity cycling, where the body is stationary while under high physiological stress.The EPE has been shown in cycling using caffeine25 and builds the basis of the valence motivation model26. This model associates dominant left relative to right frontal activation, also known as frontal alpha asymmetry (FAA), with an approach motivational system and positive affect27. More specifically, the right prefrontal cortex is considered to be specialized for negative emotions and the left prefrontal cortex for positive emotions independent of the individual disposition and therefore represents a current affective state28. The EEG-affect-exercise relationship was also studied by Petruzzello and colleagues, who found that greater relative left frontal activation pre-exercise predicted increased positive affect and reduced anxiety post-exercise in those athletes engaging in high intensity exercise.EEG activity in the alpha frequency band (8–13 Hz) is inversely related to activation of the underlying cortex29, which can be measured using the behavioral inhibition (BIS) and activation system (BAS) questionnaire30. A more pronounced BAS has been shown to make an individual highly responsive to reward cues, reflects the disposition to pursue goals and is positively associated with relatively more activation in the left than the right prefrontal cortex (higher FAA)31. The BAS has been divided into three subscales: BAS Drive reflecting the persistent pursuit of desired goals, BAS Fun reflecting a desire for new rewards and to approach potentially rewarding events, BAS Reward reflecting a positive responses to or anticipation of reward30. The BIS is hypothesized to be sensitive to signs of punishment and novelty in an attempt to control the experience of anxiety in response to anxiety-relevant cues, thus representing individuals with a more pronounced inward orientation30. To determine individual differences in the relative dominance of the BAS over the BIS, the BAS-BIS difference score can be calculated32.Asymmetric electrical activity in the prefrontal cortex has also been linked to trait motivational orientation33. Questioning the assumptions that frontal EEG asymmetry represents a trait variable, Coan et al. suggested an alternative model for the approach/withdrawal motivational model of frontal EEG asymmetry and emotion called the capability model. This model suggests more pronounced differences in frontal EEG asymmetries during emotionally salient situations indicating that individual differences in affective style are a function of innate capabilities and context34. This model was supported by a study finding a correlation of male college students’ EEG asymmetry with their BAS scores only in the presence of an attractive female experimenter, interpreting this result as evidence for the important role of context in engaging FAA in situations with high approach motivation35. Finally, recent research explored the direct relationship between the BIS/BAS trait component, FAA at rest and in response to emotional cues as a function of stimulus valence. They showed that higher BAS values explained an increase in FAA at rest and in experimental condition for positive cues, while higher BIS values marked a decrease in FAA at rest and in experimental condition in response to negative cues28.A meta-analysis of the relationship between FAA and BAS across different conditions found only a weak and inconsistent correlation between both measures36. A study concerned with the effect of self-control on asymmetric frontal cortical activation found that approach-prone persons (high BAS) were more likely to show increased relative left frontal cortical activation (high FAA) after exercising self-control37. Maximal effort endurance performance requires an exceptionally high level of self-control and the BAS seems to play a role in placebo responsiveness as well as engaging FAA as a self-control mechanism. Therefore, we measured the BIS and BAS trait to explore whether it predicts the expected increase in FAA during maximum effort cycling elicited by the administration of a PEA.Sensitivity of the BAS, specifically in the subcategory of fun and sensation seeking, in combination with contextual cues in the form of treatment descriptors has been shown to enhance placebo respondingThe purpose of this study was to investigate FAA as a cortical mechanism involved in the EPR and explore whether the BIS/BAS personality trait predicts the degree of FAA increase. Therefore, we recorded FAA as an indicator of change in the motivational valence system, in response to the administration of a highly salient PEA during an isokinetic maximum effort cycling time trial. Specifically, we hypothesized, that the placebo group will show an increase in FAA from baseline to intervention time trial, while the control group will show no change in FAA and that high scores on the BAS questionnaire including its three main subscales  and low scores on the BIS questionnaire affect this increase in FAA.38.The methods described here show only minor deviations from our previously published research protocolAn a priori power analysis (G*Power Version 3.1.9.2.) for a 2 (group) × 2 (time) × 5 (block) within-between factors repeated measures ANOVA with an assumed effect size of Cohens’ f = 0.25  revealed a required sample size of N = 20 participants. Taking possible drop-outs into account, we recruited 24 competitive cyclists , of which four dropped out due to injury and timing conflicts, leaving 20 athletes to participate in the study. One participant had to be excluded from further analysis due to a technical recording defect, leaving 19 athletes with a mean age of 37.26 (SD = ±9.82) for further analysis  to intervention (TTi) time trial. After this session, participants were expected to be sufficiently familiar with the experimental set up. The following baseline and intervention time trials were held at the same time of day (8 am ± 1 h) and the same day of the week  spaced 7 ± 1 days apart to control for performance differences based on daytime and weekday. Participants came to the laboratory fasted (12 h) and were not allowed to consume caffeine or nicotine prior to the time trials.Participants were block-randomized with a block size of N = 6 to receive either a placebo ergogenic aid (placebo group) or no treatment (control group) at the intervention time trial. Athletes visited the performance laboratory on three separate occasions. On the first visit their current training level was assessed, they were introduced to the EEG equipment and familiarized with the isokinetic cycling ergometer . They performed a practice time trial to become familiar with the time trial protocol and to reduce learning effects, which could otherwise disguise changes from baseline  and increasing by 40 W every 3 minutes. Participants cycled continuously until they were no longer able to maintain cadence above 65 revolutions per minute (rpm). Blood samples (20 µl) were taken from the right earlobe at rest and at the end of each 3 min interval to determine lactate concentration at each workload. The maximum lactate tolerance was determined using a stationary blood lactate analyser  and the individual anaerobic threshold (IAT) was calculated using the Dickhuth method40. The validation of the German version of the BIS/BAS questionnaire showed good to acceptable internal consistencies of the scales: BIS Cronbach’s α = 0.78, BAS α = 0.81, BAS drive α = 0.69, BAS fun α = 0.67, BAS reward α = 0.6940. Internal consistencies found were good to acceptable and comparable to reported ranges40 for BIS α = 0.68, BAS α = 0.84, BAS drive α = 0.74, BAS fun α = 0.75, but poor for BAS reward α = 0.49. The BAS-BIS difference score was calculated to determine individual differences in the relative strength of the BAS compared to the BIS by subtracting the z-transformed BIS score from the z-transformed BAS score for each participant in accordance with Sutton and Davidson (1997)32. After adjusting their cycling position on the ergometer, which was kept equal throughout all time trials, they performed a shortened version of the actual time trial procedure described below.After the performance test, subjects filled in the Behavioral Inhibition and Activation System questionnaire (BIS/BAS)nd and 3rd laboratory session (TTb and TTi), participants were set up with the EEG system. Subjects were instructed to drink 250 ml water during EEG setup. The protocol for TTb and TTi consisted of two warm up blocks (5 min each), five time trial blocks (9 min each) and one cool down block (5 min). An overview of all laboratory sessions is given in Fig. 41. During both warm up and cool down, athletes cycled at varying cadence and a resistance of 1.5 W/kg bodymass. During the time trial blocks, they cycled at a fixed cadence of 95 rpm and aimed for maximal power output over time. We chose an isokinetic task at a fixed cadence, because previous research has shown, that variations in cadence may influence cortical activation evident in EEG recordings43. Specifically, athletes were instructed to go “all-out” and attempt to reach maximum effort in each time trial45. All 9 min blocks were preceded and followed by a 2 min rest period, during which participants reported their current RPE score, a lactate sample was taken, a 60 second EEG rest recording was taken in an upright seating position and athletes were allowed to drink water. All instructions for the time trial protocol were displayed on a computer screen set up on a tripod in front of the ergometer. During the pedalling blocks a countdown timer was displayed. At TTb, athletes received 250 ml water before and during the time trial, while at TTi participants in the placebo group received 150 ml tab water to wash down 100 ml of a vanilla-grapefruit flavoured branched chain amino acid pudding, serving as a PEA, which has been shown previously to elicit an ergogenic placebo response in a 45 min maximum effort time trial46. In this study, we were able to demonstrate statistical equivalence between the active placebo (low dose BCAA) and its inert placebo counterpart. Athletes received an information sheet designed to increase expectancy associated with acute branched chain amino acid ingestion on high intensity endurance capacity, emphasizing its potential ergogenic properties. The exact expression was: “This study aims to investigate, whether branched chain amino acids can elicit an acute increase in endurance performance. The performance enhancing effect of these amino acids may be based on central as well as peripheral processes”. Cyclists in the control group received 250 ml water without an intervention. The precise amount of water was given to ensure equal stomach volume between groups. During the time trials all athletes were allowed to drink 250 ml of water in the designated time slots between blocks.Upon arriving to their 247 on the athlete’s skull. FCz was used as reference and AFz as ground. The active electrodes were filled with a high-viscosity electrolyte-gel for active electrodes  to ensure optimal signal transduction with impedances below 10 kΩ. EEG raw data were amplified and recorded using the BrainAmp MR system and Vision Recorder at a sampling rate of 512 Hz and processed offline using BrainVision Analyzer 2.0 . After down sampling to 256 Hz, butterworth zero phase high- and low-pass filters were applied , leaving a frequency range from 4 to 32 Hz, to eliminate drifts from sweat at very low frequencies and muscle artifacts above 40 Hz. Ocular correction was performed using a restricted infomax Independent Component Analysis48 based on a slope algorithm to detect eye blinks and eye movements from channels Fp1, Fp2 and Fpz. The detected eye blinks and movements were then separated and removed from the EEG recordings. After excluding the 4 electrodes very close to the neck musculature , a semi-automatic raw data inspection was used to detect artifacts, if the following criteria were not met: maximal voltage step of 50 µV/ms, maximal difference of 200 µV/20 ms interval, maximal amplitude between −200 µV and +200 µV and lowest activity 0.5 µV/100 ms interval. Subsequently, all data were visually inspected and marked artifacts were either confirmed or rejected. If a channel’s signal comprised >10% artifact contaminated intervals, its signal was topographically interpolated with data of its four nearest neighbors using interpolation by 4th order spherical splines with a maximal degree of the Legendre polynomial of 1049. Then, data were baseline corrected and fragmented into data sets of 4-s duration. A Hanning Window (10%) was applied to all artifact-free epochs before a Fast Fourier Transformation was used to obtain the mean power areas for the alpha frequency band (8–13 Hz), which was then exported for further analysis.At both time trials, 32 active electrodes set up in a flexible, breathable EEG cap  were arranged in accordance with the international 10:20 system50.The frontal alpha asymmetry score (FAA) was calculated by subtracting the natural log transformed alpha power in left frontal region  from the natural log transformed power in right frontal region b, TTi) × 5 (block: 9 min each) repeated measures ANOVA was applied. To test the influence of the trait variables behavioral inhibition system (BIS) and behavioral activation system (BAS) as well as their subscales  and the BAS-BIS difference score on the effect of the PEA on FAA, we calculated multiple 2  × 2  repeated measures ANCOVAs for mean FAA with the trait variables as covariate: separate ANCOVAs for each trait variable as the BAS total score and subscales were significantly intercorrelated. Main effects and interactions were reported and the effect size (η2) was calculated. Post-hoc t-tests were used to specify significant results and Cohen’s d was calculated. The level of significance was set at p ≤ 0.05. All data were analyzed using SPSS version 19.0  for Windows.To test for group differences in terms of subject characteristics, we performed student’s t-tests. To analyze effects of receiving a PEA on FAA during exercise independent of exercise duration, a 2  × 2 (time: TTt(17) = 1.51, p = 0.15), training level (IAT) (t(17) = 1.12, p = 0.28), maximal lactate tolerance (t(17) = 1.80, p = 0.09), training frequency (t(17) = −1.51, p = 0.15) and Body Mass Index (t(17) = 0.26, p = 0.80) between groups  = 5.56, p = 0.03, partial η2 = 0.25) , time and block  = 1.09, p = 0.37), or block and group  = 0.63, p = 0.64). There was no significant main effect of time  = 0.001, p = 0.98) or block  = 0.60, p = 0.67). T-tests showed no significant difference in mean FAA between groups at TTb (t(17) = 1.73, p = 0.10, d = 0.78), and a significant difference in ΔFAA between groups (t(17) = −2.36, p = 0.03, d = 1.13).The repeated measures ANOVA to show the influence of the PEA on FAA revealed a significant interaction of time and group    , ΔFAA and the BAS subscale Drive  and ΔFAA and the BAS-BIS difference score , but no significant correlations between FAA and the BAS subscales Fun  and Reward . Furthermore, there was a significant negative correlation of BIS and ΔFAA . The repeated measures ANCOVAs to show the influence of the BIS and BAS trait variables on the effect of the PEA on ΔFAA revealed a significant interaction of time and BIS  = 5.44, p = 0.03, 25) Fig. , time an36) Fig.  as well 31) Fig. . There wTo investigate a cortical mechanism involved in the ergogenic placebo response in competitive cyclists, we recorded EEG during high intensity all-out time trials on an isokinetic ergometer and measured the change in FAA in response to a PEA. We also measured the BIS/BAS trait to analyze the degree to which it is associated with these changes in FAA. The main findings of this study indicate, that athletes who received a placebo ergogenic aid showed an increase in FAA during a cycling time trial compared to athletes who received no intervention. Further, there was a significant correlation between the BAS score and the change in FAA across all athletes, showing the validity of our measure. Lastly, those athletes with a more pronounced persistence in the pursuit of desired goals  were more likely to show an increase in relative left frontal cortical activation (FAA) and those athletes with a more pronounced sensitivity for punishment, nonreward and novelty (BIS) were more likely to show a decrease in FAA in response to a placebo ergogenic aid compared to those athletes who received no intervention Fig. .28. A PEA can be considered a positive affective cue, because its administration induces high expectations by increasing reward probability in the form of performance enhancement. According to the valence motivation model, the ergogenic placebo response would then act by a positive situational affective appraisal. Although our results show a significant interaction of time and group for FAA, it is important to note, that this interaction is not solely driven by the increase in FAA in the placebo group, but also by a decrease in FAA in the control group  and one negative (angry hostility) personality trait predicted 25% of placebo analgesia responding55. The same authors also tested several other personality traits, among them the behavioral inhibition and activation system (BIS/BAS), unfortunately however, they did not report the results.Certain personality traits are thought to interact with environmental cues and thereby influence neurobiological responses to treatments, indicating their role in the modulation of the placebo response. In the past, extraversion has been linked to placebo responding in irritable bowel syndrome patientsTo the best of our knowledge, the influence of personality traits in the context of ergogenic placebo responding has not been investigated so far. We measured the BIS and BAS trait and the subscales BAS Drive, BAS Fun and BAS Reward as well as the BAS-BIS difference score to assess the degree to which it affects the change in FAA. As expected, we found a significant positive correlation between BAS and change in FAA, BAS-BIS difference and change in FAA and a significant negative correlation between BIS and change in FAA across all athletes. BIS, the subscale BAS Drive and the BAS-BIS difference score significantly co-varied with the interaction of time and FAA. This indicates that a more pronounced persistence in the pursuit of desired goals in athletes facilitates the EPR as measured by state changes in FAA Fig. , while aet al. were able to show a significant predictive role of BIS/BAS sensitivity in explaining the lateralized cortical activation in response to positive and negative emotional cues28. Future research could expand on our results by stratifying athletes based on their BIS/BAS scores or the BAS-BIS difference scores.However, our results did not show the expected influence of the overall BAS trait in the cortical response to a specific cue (here the administration of a PEA). Our results are therefore only partially in line with a recent study exploring the direct relationship between the BIS/BAS trait, lateralized frontal brain activation at rest and in response to emotional cues. Using regression analysis, Balconi 56. Our results are partially in line with the view that different personality dispositions might respond to different contextual cues. More recently, Darragh et al. suggests, that individuals with an outward oriented approach behavioral style are more likely to respond to placebo treatments, which are novel, reward and goal oriented, externally focused and accompanied by positive interaction57. A review by Horing et al. identified several predictors for placebo responders, among them the psychological construct of emotional valence attached to the event, including BAS related constructs such as goal seeking, self-efficacy, optimism and locus of control58. In a motion sickness paradigm of placebo responding, generalized self-efficacy, an internal locus of control and cognitive flexibility predicted symptom improvement in the placebo compared to the control group59. We were able to show, that the same is true for athletes scoring high on the BAS subscale Drive, low on the BIS scale or showed BAS dominance over BIS (high BAS-BIS difference score) and receiving a novel tasting PEA, which they were told has the potential to increase their endurance performance. Our findings also fit in with the capability model proposed by Coan et al., suggesting more pronounced differences in frontal EEG asymmetries during emotionally salient situations indicating that individual differences in affective style are a function of innate capabilities and context34. Considering BIS/BAS sensitivity to be a valid measure of affective style and the administration of a PEA to be a salient emotional cue, because it indicates reward probability, in accordance with this model, the PEA is more readily processed by individuals with high persistence in the pursuit of desired goals, therefore resulting in a larger FAA increase. Specifically, those individuals with a match between their individual response system and the environmental cue show higher responsiveness to a placebo ergogenic aid and those with a mismatch show lower responsiveness. We employed a novel placebo , accompanied by goal and reward oriented instructions (endurance performance enhancement) and external focus (maximizing power output) and found higher response rates in those individuals who show stamina in following their goals (BAS Drive)  Fig.  and loweve) Fig. . This pa37, which is clearly the case in a maximal effort endurance task, where the predominant response tendency would be to stop cycling in order to reduce the sensation of effort and discomfort. The study by Schmeichel et al. tested the influence of temporary self-control on FAA in response to affective cues and found that approach-prone persons (high BAS) are more likely to show increased relative left frontal cortical activation (high FAA) after exercising self-control especially in response to positive valence emotional cues37. More specifically, they found, that those subjects who scored high on BAS and low on BIS (high BAS-BIS difference score) showed increases in FAA and a low BAS-BIS difference (relative strength of the BIS over the BAS) predicted a reduction in FAA. These findings are in line with our results showing an overall positive correlation between BAS-BIS difference score and ΔFAA as well as an interaction of time and the BAS-BIS difference score, indicating antagonistic effects on placebo responding in those individuals who are more withdrawal motivated ted Fig. .The present study is limited mainly by study design constraints due to the novelty of recording EEG during high intensity endurance exercise. We did not include power output, lactate production and RPE in the analysis, because our study design was specific to the necessities of EEG recording during exercise. The study was designed with repeated interruptions to allow for EEG rest recordings, in case of problems with noise and artefacts during high intensity pedaling. Fortunately, the quality of data during cycling was high. However, these interleafed breaks did not allow for linear lactate accumulation over time and caused a ceiling effect with the RPE ratings. It is also likely, that the differences in FAA between groups would have been more pronounced in a continuous cycling time trial. Also, we cannot exclude the possibility that the small and non-significant baseline difference in FAA between groups may have contributed to a type-I error. Lastly, the sample size was relatively small and therefore the results of this study need to be confirmed by future studies investigating larger sample sizes.Despite these limitations, this study enabled a novel approach to investigate the neurophysiological link between placebo-induced expectation and endurance performance using an objective measure (EEG). While most previous studies have looked at exercise related cortical parameter by recording brain activity before or after endurance exercise or during single joint movements, we investigated the cortical correlates of placebo modulation during a high intensity endurance task for the first time.To the best of our knowledge, this is the first study, which investigated a cortical mechanism involved in the administration of a PEA in a maximal effort cycling time trial. The aim of the present research was to test the increase in FAA in response to a PEA and explore the role of the behavioural activation and inhibition system (BAS/BIS) including its subscales Drive, Fun and Reward as well as the BAS-BIS difference score as trait variables able to predict changes in FAA.According to our results, the administration of a novel, highly salient PEA may indeed lead to changes in cortical processing, specifically increased FAA compared to a control group. Athletes with a more pronounced BAS Drive and a less pronounced BIS trait appear more likely to respond to the administration of a placebo ergogenic aid with an increase in FAA, thus suggesting high persistence in the pursuit of desired goals and low sensitivity to signals of punishment and nonreward as traits mediating the EPR.60. Therefore, PEAs could be applied to enhance sports motivation and exercise adherence by increasing enjoyment and positive affect during high intensity training. Nonetheless, these results are based on competitive cyclists and require further confirmation in health oriented and rehabilitation training.It has long been established, that positive feelings during a task reliably predict future involvement in that specific activityFuture studies should look at changes in FAA in response to placebo ergogenic aids during a continuous time trial without interleafed pauses, since we showed, that recording EEG activity during vigorous cycling is possible. Employing a continuous time trial design would allow for a translation of the increase in FAA in response to a PEA to a behavioral outcome containing subjective (RPE), physiological (lactate) and objective (power output) measures of effort.


Many medicines and devices used for the healthcare of children are unlicensed and untested for use in paediatrics, and clinicians often have to rely on evidence in adults that may not be generalisable to children.4http://www.equator-network.org). The EQUATOR Network was established to improve the reliability and usability of health research literature by facilitating accurate and complete reporting of research studies.7Reporting guidelines such as Consolidated Standards Of Reporting Trials (CONSORT) and STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) aim to improve transparency, allowing identification of potential biases, critical assessments of robustness and replication in different settings.Despite the comprehensive collection of existing resources and reporting guidelines available on the EQUATOR website, there has been a lack of guidance for the reporting of paediatric studies until now.The most informative reporting guidelines are underpinned by robust methodological development, typically through establishing consensus from experts and stakeholders in an iterative process of feedback and review. However, providing robust evidence about the impact of guidelines on quality of reporting is challenging.16BMJ journal group's ‘Transparency Policy’ requests that authors follow complete reporting checklists prior to submission (http://www.bmj.com/about-bmj/resources-authors/forms-policies-and-checklists/transparency-policy). For Archives of Disease in Childhood, as for other BMJ journals, authors are referred to the EQUATOR Network website and encouraged to use appropriate guidelines to “ensure that you provide enough information for editors, peer reviewers and readers to understand how the research was performed and to judge whether the findings are likely to be reliable”. Other journals, such as PLoS Medicine, require authors to submit appropriate checklists alongside their manuscript or to provide an explanation if no relevant guideline exists.Journals implement reporting guidelines in various ways, but commonly refer to relevant reporting guidelines in their Instructions to Authors. Some journals have explicit philosophies of transparency, accuracy and completeness in reporting. For example, the Given the challenges in conducting randomised trials in children, observational studies based on population-based administrative data sources are increasingly being used to provide evidence and support quality improvement for paediatrics. Administrative or electronic health data sources contain individual-level records primarily collected for reasons other than research  and can provide rich, detailed information on patient pathways.19Positive public perception of paediatric research is crucial, both in facilitating recruitment of children into trials and in exploiting existing data sources for child health research. Both authors and journals have an important role to play in supporting the public in making informed decisions about the use of their data, through maintaining a high level of transparency and quality in reporting of paediatric health research. The use of reporting guidelines by authors and reviewers can aid careful interpretation of findings and enable those working in health policy to make evidence-based decisions on paediatric care and health systems.


Interventional cardiology procedures require full anticoagulation to prevent thrombus formation on catheters and devices with potential development of embolic complications. Bivalirudin, a short half-life direct thrombin inhibitor, has been largely used during percutaneous coronary interventions and represents the preferred alternative to heparin in patients with heparin-induced thrombocytopenia (HIT). However, few data are available about intraprocedural use of bivalirudin during transcatheter structural heart disease interventions. Activated clotting time (ACT) monitoring during bivalirudin infusion presents some limitations and it is not mandatory. We report a case of bivalirudin use in a patient with type-2 HIT during percutaneous mitral valve repair with the Mitraclip system . Despite use of standard bivalirudin dose (0.75 mg/kg bolus and 1.4 mg/kg/min infusion—reduced infusion rate was motivated by a glomerular filtration rate of 37 mL/min), the patient developed a large thrombus on the second clip during its orientation toward the mitral orifice. ACT was measured at that time and was suboptimal (240 seconds). The case was successfully managed with clip and thrombus retrieval, adjunctive 0.3 mg/kg bivalirudin bolus and increased infusion rate, and clip repositioning with ACT monitoring. This report makes the case for mandatory ACT checking and drug titration during high-risk catheter–based structural heart disease interventions, even when thromboprophylaxis is performed with bivalirudin. Additional coagulation tests may be useful to monitor bivalirudin response in similar cases. Percutaneous mitral valve repair with the Mitraclip system  has recently emerged as a safe and effective procedure to treat patients with degenerative mitral regurgitation (MR) with high surgical risk and a technically favorable anatomy. The Mitraclip is being extensively used also to treat functional MR in patients with persisting heart failure symptoms despite optimal medical treatment and, when indicated, cardiac resynchronization therapy (CRT).Interventional cardiology procedures require full anticoagulation to prevent thrombus formation on catheters and devices with potential development of embolic complications. The Mitraclip procedure implies the long permanence of bulky devices into the left atrium, a chamber characterized by low blood flow velocities, especially in patients with atrial fibrillation and a dilated atrium. Hence, thrombotic risk is high and intraprocedural antithrombotic management must be very accurate. In general, an initial bolus of heparin is given after transseptal puncture and activated clotting time (ACT) is monitored to administer additional doses and maintain an ACT value greater than 250 seconds.Heparin-induced thrombocytopenia (HIT) is a potentially catastrophic immune-mediated complication of heparin caused by antibodies to complexes of platelet factor-4 (PF4) and heparin.We report the challenging management of a patient with HIT who underwent Mitraclip procedure with bivalirudin infusion.Ongoing therapy: furosemide 500 mg/die IV, carvedilol 6.25 mg bid, potassium canrenoate 100 mg, iron supplement, pantoprazole, levothyroxine, and levosimendan.An 81-year-old woman with dilated cardiomyopathy was referred to our institution for urgent Mitraclip procedure because of severe MR and heart failure refractory to full medical treatment, including high-dose intravenous (IV) diuretics. Echocardiography showed severe left ventricular dilatation, with 20% ejection fraction, severe left and right atrial enlargement, and severe functional mitral and tricuspid regurgitation . ComorbThe Mitraclip procedure was conducted with standard technique. Saline solution without heparin was used for catheters' flushing. We administered bivalirudin bolus (0.75 mg/kg IV) immediately after transseptal puncture and at the same time a PCI-dose infusion of 1.40 mg/kg per hour was started (recommended dose reduction for CKD).After release of the first clip, during positioning of a second clip to improve procedural result, a moving image suggestive for thrombus became evident on top of the clip . ACT meVideo 1www.thieme-connect.com/products/ejournals/html/10.1055/s-0038-1675586.Intraprocedural transesophageal echocardiography showing the sessile thrombus attached to the clip. Online content including video sequences viewable at:Bivalirudin is a direct thrombin inhibitor with short half-life which has been widely used for anticoagulation in the setting of PCI, and represents the first-line intraprocedural anticoagulant for patients with HIT. It is administered with a 0.75-mg/kg bolus, followed by infusion of 1.75 mg/kg/hour in patients with GFR greater than 60 mL/min, reduced to 1.40 mg/kg/min in patients with GFR 30 to 59 mL/min. An infusion at 0.25 mg/kg/hour can be prolonged 4 to 12 hours if clinically indicated. ACT can be used to monitor effective bivalirudin administration, but it is not routinely recommended. Safety and efficacy of bivalirudin in structural heart disease procedures have been poorly investigated. The Effect of Bivalirudin on Aortic Valve Intervention Outcomes-3 (BRAVO-3) randomized trial demonstrated noninferiority of bivalirudin compared with heparin in rates of major bleeding or net adverse cardiovascular events during transcatheter aortic valve implantation.Despite the use of recommended bivalirudin dose, our patient developed a large thrombus on the clip during the procedure. ACT was measured only at that time and was actually lower than expected. The procedure was successfully completed giving an additional 0.3 mg/kg bolus, as per indications for use, and arbitrary continuous catheter flushing with a low bivalirudin dose.Limitations of ACT monitoring of bivalirudin therapy have been previously demonstrated,Accordingly, routine monitoring of ACT during PCI is not mandatory and is not usually performed. However, the instructions for use suggest to check ACT 5 minutes after the bolus and to administer additional 0.3 mg/kg bolus dose “if needed.” In our case, this was necessary to achieve effective thromboprophylaxis. We also increased infusion rate and continuously flushed the guiding catheter with low-dose bivalirudin.Differently from heparin, bivalirudin binds directly to thrombin without the need of a cofactor and therefore exhibits predictable and dose-dependent anticoagulation. While bivalirudin activity is independent of antithrombin deficiency, increased heparin clearance, and increased heparin binding proteins, which are among the causes of heparin resistance, other resistance mechanisms such as heparin have been hypothesized, including elevated factor VIII and fibrinogen.Interestingly, bivalirudin resistance (defined as ACT < 300 seconds) was reported in 2.4% of patients undergoing PCI in a single-center study.This case suggests that bivalirudin may be used in place of heparin in patients with HIT undergoing Mitraclip procedure. However, bivalirudin might be subject to resistance mechanisms similar to those previously described in patients receiving heparin, and careful ACT monitoring should be mandatory to verify achievement and permanence in the therapeutic range. When possible, additional coagulation tests should be used. Flushing of guiding catheters and devices with low-dose bivalirudin may represent a useful adjunctive measure. More data are needed to clarify if different ways of monitoring bivalirudin therapy are required for transcatheter structural heart disease interventions. Importantly, this is a single clinical case and our observations should be interpreted cautiously.


Meta-analyses of randomized controlled trials (RCTs) used to be considered as the optimum evidence to guide clinical practices. Generally, a high-quality meta-analysis with conclusive information should meet the minimum requirements of a well-conducted RCT, which includes prospective protocol development, limitation of bias, and adequate sample size . Convers2) with the most included RCTs to estimate whether the evidence is enough reliable and credible. TSA in Fig. Z-curve did not cross the trial sequential monitoring boundary for benefit and the required information size boundary, which suggested that the current evidence (the positive effect of CAI on PaCO2) was inconclusive. In addition, TSA on PaCO2 showed that the required information size (347 patients) is not reached due to weak statistical power. So, the effects of CAI therapy for patients with respiratory failure and metabolic alkalosis may very likely be overrated.Trial sequential analysis (TSA) was introduced to monitor potential random error, false positive, and false negative in meta-analyses of RCTs . MoreoveCollectively, for meta-analyses of RCTs with limited information size, TSA is a good choice to monitor the potential overestimation of the overall pooled effect. Furthermore, it is worthwhile to further discussion whether TSA should be routinely performed in meta-analyses of RCTs. We thank Meng-Si Luo et al. for their interest in our work, and for highlighting one the limitations of the literature in this field, namely the limited number of published randomized controlled trials (RCTS). In our conclusion, we do acknowledge this important limitation and the need for larger, well designed, and RCTs addressing clinically important outcomes such as mortality, duration of hospital stay, and duration of mechanical ventilation. Meng-Si Luo et al. propose the use of Trial Sequential Analysis (TSA) to assess the ‘imprecision’ of outcomes. In a recent expert panel consensus statement, the Cochrane scientific committee recommended against the use of sequential methods for the main analysis, or to draw main conclusions. The statement encourages authors to interpret evidence based on the estimated magnitude of the effect of intervention and its uncertainty , rather than focusing primarily on the rejection of the null hypothesis of no treatment effect  .Our approach was consistent with the recent Cochrane recommendations, as we did not draw binary interpretation of the effect estimate as “significant” or “non-significant”. Instead, we presented our results using a confidence interval and assessed heterogeneity using the I2 statistic, then used the GRADE methodology to rate the certainty of evidence. In applying GRADE, we judged imprecision as a reason for rating down the certainty of evidence for all the clinically important outcomes. , 7 If weOne of the main reasons Cochrane adopted the above recommendation is to “support the decision maker and end user by providing the best and latest evidence, but that interpretation of that evidence should be left to the user to make within their own context.” We are happy our approach was consistent with that recommendation given the aim of our review is to support clinicians providing care to critically ill patients.