Does Aspirin Consumption Affect the Presentation or Severity of Acute Myocardial Infarction?

BACKGROUND: While consumption of aspirin has been shown to decrease the occurrence of nonfatal cardiac events, the majority of studies have not demonstrated any impact of aspirin intake on cardiovascular mortality. The present population-based study explores the possibility that aspirin consumption affects the presentation and severity of acute myocardial infarction (AMI), and hence the likelihood of clinical detection. METHODS: We monitored the use of aspirin before admission for 2114 patients with a validated diagnosis of AMI in 16 hospitals in the Worcester, Mass, metropolitan area during 1986, 1988, and 1990. The AMIs were characterized as Q wave vs non-Q wave and large (peak creatine kinase levels more than five times normal) vs small (peak creatine kinase levels less than two times normal). RESULTS: A total of 332 patients (16%) with validated AMI took aspirin before hospital admission. Nearly 65% of aspirin users had non-Q wave AMIs, compared with 49% of nonaspirin users. Thirty percent of aspirin users sustained small AMIs, compared with 22% of nonaspirin users. These findings persisted after stratifying for previous AMI, history of coronary disease, receipt of thrombolytic therapy, and exclusion of early hospital deaths. Using multivariable regression models to control for age, gender, previous evidence of coronary disease, and use of other medications, prior aspirin consumption remained independently associated with AMI type (non-Q-wave AMI) and smaller infarct size. CONCLUSION: Aspirin consumption appears to modify the presentation of AMI, increasing the likelihood that the infarct will be of the small, non-Q-wave variety.