Association of hospital myocardial infarction volume with adherence to American College of Cardiology/American Heart Association performance measures: Insights from the National Cardiovascular Data Registry

Background Adherence to guideline-based therapy improves patient outcomes after acute myocardial infarction (AMI) and hospital AMI volume is associated with reperfusion care, but the extent hospital AMI volume is associated with overall guideline adherence is unclear. Methods and Results We studied 486 hospitals treating 249,877 AMI patients in ACTION Registry-GWTG from January 1, 2007, to March 31, 2011. Hospital adherence to each American College of Cardiology/American Heart Association performance measure was compared between tertiles defined by hospital AMI volume: low (<= 108 cases/y), middle (>= 109 and <= 227 cases/y), and high (>= 228 cases/y). Multivariable logistic regression, adjusting for patient and hospital characteristics, was used to examine the association between annual AMI volume and adherence to each measure. Similar modeling was used to evaluate the relationship between AMI volume and in-hospital mortality. Compared with high volume hospitals, lower-volume hospitals were less likely to be academically affiliated, or to have cardiac surgery capabilities, electronic health records, or dedicated tobacco treatment services. Higher-volume hospitals had greater adherence to each performance measure, except aspirin use at arrival and reperfusion therapy. The greatest difference was in the rates of referral to cardiac rehabilitation (59%, 76%, and 83% in low-, middle-, and high-volume hospitals, respectively). After multivariable adjustment, higher AMI volume (up to 400 AMI patients/y) remained associated with higher-performance measure adherence. There was no association between AMI volume and in-hospital mortality after adjusting for patient and hospital characteristics. Conclusions Higher hospital AMI volume was correlated with better adherence to process of care measures, but not in-hospital mortality.