the design of the china peace - retrospective ami study has been published previously.8 in brief , we developed a nationally representative sample of hospitalizations for ami in 2001 , 2006 , and 2011 using a 2-stage random sampling design . in the first stage , we identified hospitals using a simple random sampling procedure within 5 geographical - economic strata of china : eastern - rural ; central - rural ; western - rural ; eastern - urban ; and central / western - urban regions . we used these strata because hospital volumes and clinical capacities differ between urban and rural areas as well among the 3 official geographical regions ( eastern , central , and western ) of mainland china . we combined central and western urban regions given their similar per capita income and health services capacity . in the 3 rural strata , the sampling framework consisted of the central hospital in each of the predefined rural regions ( 2010 central hospitals in 2010 rural regions ) . in the 2 urban strata , the sampling framework consisted of the highest - level hospitals in each of the predefined urban regions ( 833 hospitals in 287 urban regions ) . we randomly selected representative hospitals from 2011 to assess current practices and traced this cohort backward to 2006 and 2001 to describe temporal trends . in the second stage , using systematic random sampling procedures , we drew cases from each sampled hospital using the local hospital database for patients with ami in 2001 , 2006 , and 2011 . ami cases were identified using a principal discharge diagnosis of ami based on international classification of diseases versions 9 or 10 , given that hospitals in china are mandated by the ministry of health to list this information on the first page of the medical record , and in rare cases when such information was not available , we confirmed the diagnosis through medical record review . data abstraction quality was monitored by randomly auditing 5% of the medical charts , with overall accuracy exceeding 98% . the central ethics committee at the china national center for cardiovascular diseases , or local internal ethics committees approved the china peace - retrospective ami study . the funder of the study had no role in study design , data collection , data analysis , data interpretation , or writing of the report . we limited study samples to patients potentially eligible for spironolactone , namely , those with known hf or diabetes at discharge . patients who had a length of hospital stay shorter than 24  hours were excluded to ensure that all patients had sufficient opportunity to receive spironolactone . subsequently , we classified patients into 1 of 4 groups : the  ideal  group consisted of patients with a documented lvef 40% and no contraindication to spironolactone ; the  contraindicated  group consisted of patients with a contraindication ( serum potassium > 5  mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; the  not indicated  group consisted of patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; and the  unknown indications  group consisted of patients whose lvef was not measured during the hospitalization . data elements collected included demographic information , medical history , patient characteristics at presentation , hospital characteristics , laboratory parameters , concomitant therapy , and documented diagnosis . cardiovascular risk ( cvr ) factors were coded as present if diagnosed before or during admission ; clinical characteristics , including vital signs , represented those recorded on admission . to capture the laboratory values likely to influence the decision about spironolactone therapy in patients who received the drug , we used the last potassium and creatinine values before administration of medication . for patients who ultimately did not receive spironolactone , we used the highest lab value recorded during hospitalization to ensure identification of any possible contraindication . lvef values were based on echocardiography , radionuclide angiography , or computerized tomography coronary angiography . to examine temporal trends in spironolactone therapy , we used the cochran - armitage tests and applied weights proportional to the inverse sampling fraction of hospitals to account for differences in the sampling fraction for each time period . when exploring patient and hospital characteristics associated with the use of spironolactone , categorical variables were expressed as frequencies and percentages and analyzed using chi - square tests . among all the variables , missing data were rare and occurred only for the age variable ( 0.1% ) , which was imputed to the overall median to avoid case - wise deletion . we used logistic regression models to identify predictors independently associated with spironolactone use in different patient groups by indications . variables in models include demographic characteristics , cvr factors , medical history , conditions and vital signs on admission , estimated glomerular filtration rate ( egfr ) , ami type , economic - geographical region , rural / urban region , and years . in addition , we also included hospital characteristics , such as teaching status and percutaneous coronary intervention ( pci ) capability ( table 1 ) . a generalized estimating equation model was developed to account for clustering of patients within hospitals . all variables in the bivariate model were included in the multivariable model except those with frequencies under 1% . bivariate analysis of characteristics associated with spironolactone therapy among ideal patients ace inhibitor indicates angiotensin - converting enzyme inhibitor ; ami , acute myocardial infarction ; arb , angiotensin receptor blocker ; egfr , estimated glomerular filtration rate ; nstemi , non - st - segment elevation myocardial infarction ; pci , percutaneous coronary intervention ; sbp , systolic blood pressure ; stemi , st - segment elevation myocardial infarction . all comparisons were 2-tailed , with p<0.05 considered statistically significant . all statistical analyses were performed using sas software ( version 9.2 ; sas institute , cary , nc ) and r software ( version 3.0.2 ; r foundation for statistical computing , vienna , austria ) . the design of the china peace - retrospective ami study has been published previously.8 in brief , we developed a nationally representative sample of hospitalizations for ami in 2001 , 2006 , and 2011 using a 2-stage random sampling design . in the first stage , we identified hospitals using a simple random sampling procedure within 5 geographical - economic strata of china : eastern - rural ; central - rural ; western - rural ; eastern - urban ; and central / western - urban regions . we used these strata because hospital volumes and clinical capacities differ between urban and rural areas as well among the 3 official geographical regions ( eastern , central , and western ) of mainland china . we combined central and western urban regions given their similar per capita income and health services capacity . in the 3 rural strata , the sampling framework consisted of the central hospital in each of the predefined rural regions ( 2010 central hospitals in 2010 rural regions ) . in the 2 urban strata , the sampling framework consisted of the highest - level hospitals in each of the predefined urban regions ( 833 hospitals in 287 urban regions ) . we randomly selected representative hospitals from 2011 to assess current practices and traced this cohort backward to 2006 and 2001 to describe temporal trends . in the second stage , using systematic random sampling procedures , we drew cases from each sampled hospital using the local hospital database for patients with ami in 2001 , 2006 , and 2011 . ami cases were identified using a principal discharge diagnosis of ami based on international classification of diseases versions 9 or 10 , given that hospitals in china are mandated by the ministry of health to list this information on the first page of the medical record , and in rare cases when such information was not available , we confirmed the diagnosis through medical record review . data abstraction quality was monitored by randomly auditing 5% of the medical charts , with overall accuracy exceeding 98% . the central ethics committee at the china national center for cardiovascular diseases , or local internal ethics committees approved the china peace - retrospective ami study . the funder of the study had no role in study design , data collection , data analysis , data interpretation , or writing of the report . we limited study samples to patients potentially eligible for spironolactone , namely , those with known hf or diabetes at discharge . patients who had a length of hospital stay shorter than 24  hours were excluded to ensure that all patients had sufficient opportunity to receive spironolactone . subsequently , we classified patients into 1 of 4 groups : the  ideal  group consisted of patients with a documented lvef 40% and no contraindication to spironolactone ; the  contraindicated  group consisted of patients with a contraindication ( serum potassium > 5  mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; the  not indicated  group consisted of patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; and the  unknown indications  group consisted of patients whose lvef was not measured during the hospitalization . data elements collected included demographic information , medical history , patient characteristics at presentation , hospital characteristics , laboratory parameters , concomitant therapy , and documented diagnosis . cardiovascular risk ( cvr ) factors were coded as present if diagnosed before or during admission ; clinical characteristics , including vital signs , represented those recorded on admission . to capture the laboratory values likely to influence the decision about spironolactone therapy in patients who received the drug , we used the last potassium and creatinine values before administration of medication . for patients who ultimately did not receive spironolactone , we used the highest lab value recorded during hospitalization to ensure identification of any possible contraindication . lvef values were based on echocardiography , radionuclide angiography , or computerized tomography coronary angiography . to examine temporal trends in spironolactone therapy , we used the cochran - armitage tests and applied weights proportional to the inverse sampling fraction of hospitals to account for differences in the sampling fraction for each time period . when exploring patient and hospital characteristics associated with the use of spironolactone , categorical variables were expressed as frequencies and percentages and analyzed using chi - square tests . among all the variables , missing data were rare and occurred only for the age variable ( 0.1% ) , which was imputed to the overall median to avoid case - wise deletion . we used logistic regression models to identify predictors independently associated with spironolactone use in different patient groups by indications . variables in models include demographic characteristics , cvr factors , medical history , conditions and vital signs on admission , estimated glomerular filtration rate ( egfr ) , ami type , economic - geographical region , rural / urban region , and years . in addition , we also included hospital characteristics , such as teaching status and percutaneous coronary intervention ( pci ) capability ( table 1 ) . a generalized estimating equation model was developed to account for clustering of patients within hospitals . all variables in the bivariate model were included in the multivariable model except those with frequencies under 1% . bivariate analysis of characteristics associated with spironolactone therapy among ideal patients ace inhibitor indicates angiotensin - converting enzyme inhibitor ; ami , acute myocardial infarction ; arb , angiotensin receptor blocker ; egfr , estimated glomerular filtration rate ; nstemi , non - st - segment elevation myocardial infarction ; pci , percutaneous coronary intervention ; sbp , systolic blood pressure ; stemi , st - segment elevation myocardial infarction . all statistical analyses were performed using sas software ( version 9.2 ; sas institute , cary , nc ) and r software ( version 3.0.2 ; r foundation for statistical computing , vienna , austria ) . the nationally representative samples described in the china peace - retrospective ami study consisted of 16  100 patients hospitalized for ami in 162 hospitals across china ( figure 1a ) , with the 2011 sample representing 245  720 patients across china . after excluding patients with a length of stay shorter than 24  hours , and those without hf or diabetes when discharged , we identified 6906 patients ( 12.2% in 2001 , 27.7% in 2006 , and 60.1% in 2011 ) who were potentially eligible for spironolactone ( figure 1b ) . across all years , median age was 69  years ( interquartile range , 59 to 76 ) and 35.8% were female . among these patients , 44.2% had diabetes , and almost three quarters of patients ( 73.9% ) had hf - among them cvr factors were common : 57.9% had hypertension ( htn ) , 29.8% were current smokers , and 28.0% had coronary artery disease . a , flow diagram showing the process used to produce a nationally representative sampling of hospitals in china . b , flow diagram showing the approach to classify patients into 4 groups according to their indications for spironolactone .  n  represents number of patients . there were notable changes in the relative proportion of the 4 patient groups over time ( figure 2 ) . for example , the proportion of  ideal  patients doubled from 2001 to 2006 ( 4.5% to 9.1% ) and remained stable thereafter ( 10.2% in 2011 ) . in contrast , the proportion of  contraindicated  patients varied little across the 3  years ( 13.0% , 11.9% , and 10.2% in 2001 , 2006 , and 2011 , respectively ) . patients increased markedly over the years ( from 15.6% in 2001 to 46.8% in 2011 ; p<0.001 for trend ) , whereas that of  unknown indications acute myocardial infarction patients with heart failure or diabetes grouped by their eligibility for spironolactone in 2001 , 2006 , and 2011 . ideal : patients with a left ventricular ejection fraction ( lvef ) 40% and without contraindications to spironolactone ; contraindicated : patients with a contraindication ( serum potassium > 5 mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; not indicated : patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; unknown indications : patients whose lvef was not measured during the hospitalization . overall , the weighted rate of spironolactone use in 2011 differed among patients in each group : 72.4% in  ideal  ; 27.5% in  contraindicated  ; 38.3% in  not indicated  ; and 35.1% in  unknown indications . spironolactone use increased in all groups over the past decade : among  ideal  patients , the weighted rate of use increased from 28.6% in 2001 to 68.5% in 2006 and to 72.4% in 2011 ( p<0.001 for trend ) , whereas for  contraindicated  patients it increased from 11.4% in 2001 to 22.4% in 2006 and to 27.5% in 2011 ( p=0.002 for trend ) . similar increases were observed among  not indicated  patients ( p=0.007 for trend ) and  unknown indications  patients ( p<0.001 for trend ; figure 3 ) . given that spironolactone can also be used to treat htn or as a concomitant therapy in hf with reduced lvef , we performed a post - hoc analysis describing spironolactone use in a specific subgroup of  not indicated  patients , namely , those with neither htn nor hf . in this subgroup of patients in 2011 , 17.2% received spironolactone . spironolactone use ( weighted ) among different groups of acute myocardial infarction patients with heart failure or diabetes according to their eligibility for spironolactone in 2001 , 2006 , and 2011 . ideal : patients with a left ventricular ejection fraction ( lvef ) 40% and without contraindications to spironolactone ; contraindicated : patients with a contraindication ( serum potassium > 5  mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; not indicated : patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; unknown indications : patients whose lvef was not measured during the hospitalization . bivariate analysis of the factors associated with the use of spironolactone among ideal patients is shown in table 1 . all characteristics were entered into the multivariable model to determine independent predictors of use ( figure 4 ) . specifically , older patients ( 65  year ) were more likely to be treated than younger patients ( 72.2% vs. 55.1% ; or , 2.07 ; 95% ci , 1.30 to 3.30 ) . patients with htn or with symptoms of hf at admission were both more likely to receive spironolactone ( 70.2% vs. 61.1% ; or , 1.57 ; 95% ci , 1.11 to 2.23 and 72.9% vs. 52.1% ; or , 2.00 ; 95% ci , 1.18 to 3.36 , respectively ) than those without these comorbidities . patients in pci - capable hospitals were more likely to be treated ( 71.1% vs. 51.6% ; or , 2.12 ; 95% ci , 1.12 to 4.02 ) . . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . egfr indicates estimated glomerular filtration rate ; or , odds ratio ; pci , percutaneous coronary intervention . characteristics in multivariable analysis that remained independently associated with the use of spironolactone in the other 3 groups are shown in figures5 through 7 . contraindicated  and  unknown indications  groups ( or , 1.84 ; 95% ci , 1.15 to 2.94 and or , 1.74 ; 95% ci , 1.31 to 2.29 , respectively ) . patients > 65  years old and patients with htn had a high likelihood of receiving spironolactone among both  not indicated  and  unknown indication  groups . across all groups , patients with symptoms of hf at admission to the hospital were more likely to be treated with spironolactone ( contraindicated : or , 3.26 ; 95% ci , 2.05 to 5.16 ; unknown indications : or , 2.60 ; 95% ci , 2.12 to 3.18 ; not indicated : or , 2.16 ; 95% ci , 1.73 to 2.69 ) . factors associated with spironolactone therapy among  contraindicated  patients in multivariable model . . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . factors associated with spironolactone therapy among  not indicated  patients in the multivariable model . . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . factors associated with spironolactone therapy among  unknown indications  patients in the multivariable model . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . egfr indicates estimated glomerular filtration rate ; or , odds ratio ; sbp , systolic blood pressure . the nationally representative samples described in the china peace - retrospective ami study consisted of 16  100 patients hospitalized for ami in 162 hospitals across china ( figure 1a ) , with the 2011 sample representing 245  720 patients across china . after excluding patients with a length of stay shorter than 24  hours , and those without hf or diabetes when discharged , we identified 6906 patients ( 12.2% in 2001 , 27.7% in 2006 , and 60.1% in 2011 ) who were potentially eligible for spironolactone ( figure 1b ) . across all years , median age was 69  years ( interquartile range , 59 to 76 ) and 35.8% were female . among these patients , 44.2% had diabetes , and almost three quarters of patients ( 73.9% ) had hf - among them cvr factors were common : 57.9% had hypertension ( htn ) , 29.8% were current smokers , and 28.0% had coronary artery disease . a , flow diagram showing the process used to produce a nationally representative sampling of hospitals in china . b , flow diagram showing the approach to classify patients into 4 groups according to their indications for spironolactone .  n  represents number of patients . there were notable changes in the relative proportion of the 4 patient groups over time ( figure 2 ) . for example , the proportion of  ideal  patients doubled from 2001 to 2006 ( 4.5% to 9.1% ) and remained stable thereafter ( 10.2% in 2011 ) . in contrast , the proportion of  contraindicated  patients varied little across the 3  years ( 13.0% , 11.9% , and 10.2% in 2001 , 2006 , and 2011 , respectively ) . patients increased markedly over the years ( from 15.6% in 2001 to 46.8% in 2011 ; p<0.001 for trend ) , whereas that of  unknown indications acute myocardial infarction patients with heart failure or diabetes grouped by their eligibility for spironolactone in 2001 , 2006 , and 2011 . ideal : patients with a left ventricular ejection fraction ( lvef ) 40% and without contraindications to spironolactone ; contraindicated : patients with a contraindication ( serum potassium > 5 mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; not indicated : patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; unknown indications : patients whose lvef was not measured during the hospitalization . overall , the weighted rate of spironolactone use in 2011 differed among patients in each group : 72.4% in  ideal  ; 27.5% in  contraindicated  ; 38.3% in  not indicated  ; and 35.1% in  unknown indications . spironolactone use increased in all groups over the past decade : among  ideal  patients , the weighted rate of use increased from 28.6% in 2001 to 68.5% in 2006 and to 72.4% in 2011 ( p<0.001 for trend ) , whereas for  contraindicated  patients it increased from 11.4% in 2001 to 22.4% in 2006 and to 27.5% in 2011 ( p=0.002 for trend ) . similar increases were observed among  not indicated  patients ( p=0.007 for trend ) and  unknown indications  patients ( p<0.001 for trend ; figure 3 ) . given that spironolactone can also be used to treat htn or as a concomitant therapy in hf with reduced lvef , we performed a post - hoc analysis describing spironolactone use in a specific subgroup of  not indicated  patients , namely , those with neither htn nor hf . in this subgroup of patients in 2011 , 17.2% received spironolactone . spironolactone use ( weighted ) among different groups of acute myocardial infarction patients with heart failure or diabetes according to their eligibility for spironolactone in 2001 , 2006 , and 2011 . ideal : patients with a left ventricular ejection fraction ( lvef ) 40% and without contraindications to spironolactone ; contraindicated : patients with a contraindication ( serum potassium > 5  mmol / l , or serum creatinine > 2.5  mg / dl [ men ] or > 2.0  mg / dl [ women ] , or documented allergy to spironolactone ) ; not indicated : patients with neither indication ( ie , lvef > 40% ) nor contraindication to spironolactone ; unknown indications : patients whose lvef was not measured during the hospitalization . bivariate analysis of the factors associated with the use of spironolactone among ideal patients is shown in table 1 . all characteristics were entered into the multivariable model to determine independent predictors of use ( figure 4 ) . specifically , older patients ( 65  year ) were more likely to be treated than younger patients ( 72.2% vs. 55.1% ; or , 2.07 ; 95% ci , 1.30 to 3.30 ) . patients with htn or with symptoms of hf at admission were both more likely to receive spironolactone ( 70.2% vs. 61.1% ; or , 1.57 ; 95% ci , 1.11 to 2.23 and 72.9% vs. 52.1% ; or , 2.00 ; 95% ci , 1.18 to 3.36 , respectively ) than those without these comorbidities . patients in pci - capable hospitals were more likely to be treated ( 71.1% vs. 51.6% ; or , 2.12 ; 95% ci , 1.12 to 4.02 ) . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . egfr indicates estimated glomerular filtration rate ; or , odds ratio ; pci , percutaneous coronary intervention . characteristics in multivariable analysis that remained independently associated with the use of spironolactone in the other 3 groups are shown in figures5 through 7 . contraindicated  and  unknown indications  groups ( or , 1.84 ; 95% ci , 1.15 to 2.94 and or , 1.74 ; 95% ci , 1.31 to 2.29 , respectively ) . patients > 65  years old and patients with htn had a high likelihood of receiving spironolactone among both  not indicated  and  unknown indication  groups . across all groups , patients with symptoms of hf at admission to the hospital were more likely to be treated with spironolactone ( contraindicated : or , 3.26 ; 95% ci , 2.05 to 5.16 ; unknown indications : or , 2.60 ; 95% ci , 2.12 to 3.18 ; not indicated : or , 2.16 ; 95% ci , 1.73 to 2.69 ) . . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . factors associated with spironolactone therapy among  not indicated  patients in the multivariable model . . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . factors associated with spironolactone therapy among  unknown indications  patients in the multivariable model . the adjusted odds ratio of 1 shows no difference to receive spironolactone therapy among ideal patients . each dot represents the point estimate of the effect of that variable in the model ; the line shows the 95% confidence interval ( ci ) . egfr indicates estimated glomerular filtration rate ; or , odds ratio ; sbp , systolic blood pressure . in this national quality assessment analyzing spironolactone use among patients with ami in china , we found that spironolactone use increased over time . however , suboptimal patient identification and selection were detected throughout the study period and persisted in 2011 . although more patients underwent lvef assessment , which is necessary to determine their eligibility for spironolactone , one third of patients did not have an lvef assessment during their hospitalization for ami in 2011 . spironolactone use among patients who may not benefit and those with contraindications was common and such use increased significantly over time . our findings indicate that the chinese health care system rapidly responded to new information that highlighted the utility of spironolactone , but also appears to have driven increased use among patients who lack a strong indication , albeit at a lower rate than in ideal patients . these findings highlight an opportunity for hospitals in china to improve the translation of evidence into clinical practice . to our knowledge , this is the first comprehensive , nationally representative quality assessment of spironolactone use in ami in china . previous studies evaluating the use of aldosterone antagonists among ami patients in other countries have focused only on patients with definite indications for treatment.911 in contrast , our study describes to what extent patients with ami are evaluated for spironolactone and shows that spironolactone is used not only among patients with indications , but also those with contraindications , without indications , and with indications unknown . additionally , the use of a nationally representative sample ensures that the findings of this analysis are broadly applicable across china and can serve as the basis for future quality improvement initiatives . lvef assessment among patients with ami improved over the past decade , which created more opportunities to consider spironolactone therapy ; however , further improvement is possible . in 2001 , indications for two thirds of patients were unknown and only 4.5% of the cohort was classified as ideal  patients increased to 10% ; however , one third of patients still lacked an lvef assessment . in comparison , among patients in the united states with ami from 2007 to 2009 , the rate of lvef assessment was reported to be 91.0%.12 it should be noted that lvef assessment is a critical component of the care of patients with ami because it enables risk stratification and guides the prescription of other therapies as well , for instance , inhibitors of angiotensin converting enzyme ( ace ) . the increasing use of spironolactone among ideal patients in china over time is encouraging . in 2001 , spironolactone use among  ideal  patients was no better than other groups , but it increased sharply thereafter , possibly in response to the ephesus study , which was published after 2001 and clearly supported the use of aldosterone antagonists in this patient population.6 there are no previous studies in china with which to compare our results . however , a registry - based study in spain reported that 54.8% patients with ami and hf received aldosterone antagonist in hospital between 2006 and 20089 ; and in the united states , the prescription rate of aldosterone antagonists at discharge among patients with ami and reduced lvef was only approximately 15% from 2009 to 2010.10,11 although the utilization seems to be better in china than in other countries , there remains room for further improvement , given the potential benefit of this agent . the substantial use of spironolactone among patients with contraindications  nearly 1 in 4 patients  was concerning and indicates a gap in the patient selection process that can expose patients to potential harm , such as worsening hyperkalemia or significant renal dysfunction.4,13 it must be noted that there may be circumstances in which spironolactone use is contraindicated according to the guidelines , yet clinicians perceive that the benefit of the drug will outweigh its risks . for example , some recently published studies demonstrate that the benefit of aldosterone antagonists may offset its risk in the setting of moderate hyperkalemia.14,15 nonetheless , the rising proportion of  contraindicated  patients being treated with spironolactone is consistent with a study in the united states and suggests that the growth in use may , at times , be indiscriminate.16 spironolactone was frequently used among patients without clear indications , namely , those with lvef > 40% . it should be noted that the recent treatment of preserved cardiac function heart failure with an aldosterone antagonist study found no benefit of spironolactone use in patients with hf and a preserved lvef.17 in the subgroup of patients without any identifiable indication , including htn or systolic hf , 17.2% were treated , suggesting that a substantial number of patients are receiving a drug that has limited benefit for their condition , and with a potential for adverse effects . in all 4 groups , such a pattern indicates that the presence of hf was a common and important trigger for spironolactone prescription by clinicians and implies a wide acceptance of the drug in hf . additionally , the steady rate of loop diuretic use among patients with hf indicates that spironolactone was not being systematically substituted for loop diuretics , and that other factors are driving spironolactone uptake . the selection issues identified in this analysis may impede the transfer of benefit to appropriate patients . quality improvement initiatives emphasizing the appropriate use of spironolactone are warranted to improve patient selection and avoid adverse events . however , to ensure accurate abstraction , we had strict definitions for all variables and employed quality control procedures to insure that the abstraction accuracy reached 98% . second , we may not have captured all patients with contraindications owing to inadequate physician documentation or unmeasured serum chemistry , which may lead to errors in the estimation of ideal patients and contraindicated patients . third , the benefit of aldosterone antagonists for ami patients was demonstrated in the ephesus study , which studied eplerenone , rather than spironolactone , which is the only aldosterone antagonist available in china . however , the structural similarity of spironolactone and eplerenone suggests that they may have similar efficacy , and guidelines endorse the use of both drugs for patients with ami . last , because data were abstracted from deidentified medical charts , we were unable to determine whether some patients were included in multiple study years , or had multiple admissions during the same year ; however , given the 5-year difference between the 3 time points , and the random sampling method , the number of such patients is likely to be minimal . first , our analysis used data abstracted from medical records . however , to ensure accurate abstraction , we had strict definitions for all variables and employed quality control procedures to insure that the abstraction accuracy reached 98% . second , we may not have captured all patients with contraindications owing to inadequate physician documentation or unmeasured serum chemistry , which may lead to errors in the estimation of ideal patients and contraindicated patients . third , the benefit of aldosterone antagonists for ami patients was demonstrated in the ephesus study , which studied eplerenone , rather than spironolactone , which is the only aldosterone antagonist available in china . however , the structural similarity of spironolactone and eplerenone suggests that they may have similar efficacy , and guidelines endorse the use of both drugs for patients with ami . last , because data were abstracted from deidentified medical charts , we were unable to determine whether some patients were included in multiple study years , or had multiple admissions during the same year ; however , given the 5-year difference between the 3 time points , and the random sampling method , the number of such patients is likely to be minimal . we identified opportunities to optimize the use of spironolactone post - ami in chinese clinical practice , including wider lvef assessment , more - careful selection of patients , and increasing the utilization among ideal patients . our findings shed light on existing practice patterns in the treatment of ami in china , serve as the basis for future quality assessment efforts , and illuminate the barriers to more - appropriate use of evidence - based therapies for all countries seeking opportunity to optimize care . this project was partly supported by the research special fund for public welfare industry of health ( 201202025 ) from the national health and family planning commission of china . dr krumholz is supported by grant u01hl105270 - 05 ( center for cardiovascular outcomes research at yale university ) from the national heart , lung , and blood institute . dr ross is supported by the national institute on aging ( k08ag032886 ) and by the american federation for aging research through the paul b. beeson career development award program . the funders had no role in study design , data collection and analysis , decision to publish , or preparation of the manuscript . dr krumholz reports being the recipient of research grants from medtronic and johnson & johnson , through yale university , to develop methods of clinical trial data sharing , and the chair of a cardiac scientific advisory board for unitedhealth . dr ross reports that he is a member of a scientific advisory board for fair health , inc . dr masoudi receives salary support from the american college of cardiology for his role as the senior medical officer of the national cardiovascular data registries . appendix s1 . members of the china peace collaborative group - retrospective ami study site investigators and china peace study consultants .