Community Patterns of Acute Myocardial Infarction Therapy and Survival

Background. Reports from clinical trials and observational studies have characterized recent temporal trends and treatment patterns for AMI. However, have examined differences in patterns of treatment for patients presenting with ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI). Additionally, reports on survival after AMI using propensity scores accounting for all medical therapies received during hospitalization are limited. We examined 21-year trends in the use of 10 medical therapies and procedures by STEMI and NSTEMI classification and associated survival using propensity score (PS) adjustment in the ARIC Community Surveillance Study (ARIC). Methods. We analyzed data from 30986 definite or probable MIs between 1987 and 2008 among all residents 35-74 years of age in the four geographically defined US communities of the ARIC Study. We used weighted multivariable Poisson regression to estimate average annual percent changes in medical therapy use over the study period. We then used 4 PS adjustment strategies to account for the non-randomized study design and the receipt of other medical therapies during hospitalization. Results. From 1987 - 2008, 6106 (19.7%) hospitalized events were classified as STEMI, and 20302 (65.5%) were classified as NSTEMI. Among STEMI patients, increases (%; 95% CI) were noted in the use of ACE inhibitors (6.4; 5.7, 7.2), non-aspirin anti-platelets (5.0; 4.0, 6.0), lipid-lowering medications (4.5; 3.1, 5.8), beta blockers (2.7; 2.4, 3.0), aspirin (1.2; 1.0, 1.3), and heparin (0.8; 0.4, 1.3). Among NSTEMI patients, the use of ACE inhibitors (5.5; 5.0, 6.1), non-aspirin anti-platelets (3.7; 2.7, 4.7), lipid-lowering medications (3.0; 1.9, 4.1), beta blockers (4.2; 3.9, 4.4) increased. Calcium channel blocker use decreased for both STEMI (-8.8%;-9.6,-8.0) and NSTEMI (-5.6; -6.1,-5.1) patients over the study period. Medication and procedure use was associated with decreased risk of mortality at 30, 90, and 365 days after hospitalization for beta blockers, lipid lowering medications, aspirin, PCI, CABG and t-PA, even after adjustment for all medications received during hospitalization. Conclusion. We found trends of increasing use of evidence-based medicine for both STEMI and NSTEMI patients over the past 21 years. Future research should examine the broader public health impact of increasing adherence to clinical therapy guidelines.