PREVIOUS ASPIRIN USE MAY ATTENUATE THE SEVERITY OF THE MANIFESTATION OF ACUTE ISCHEMIC SYNDROMES

Background The present study was designed to investigate whether the p rior use of aspirin could influence the severity of the manifestation of acute coronary artery syndromes, given the well-documented observat ions that aspirin can prevent myocardial infarction, stroke, and death in cardiovascular disease. Methods and Results A series of 539 consec utive patients admitted to the Coronary Care Unit of a General Hospita l was carefully characterized in a study with an ambidirectional desig n, with regard to previous medical history, aspirin use, and subsequen t hospital diagnosis. Among the 214 patients previously taking aspirin , the hospital diagnosis was myocardial infarction in 24% and unstable angina in 76% compared with 54% and 46%, respectively, among the 325 not taking aspirin (P<.0001), for a reduction in the odds ratio of myo cardial infarction with aspirin of 72% (95% CI, 59% to 90%). The decre ase in odds was homogeneous in all subsets studied and independent of age, sex, previous angina, or previous myocardial infarction. The myoc ardial infarction was of a Q-wave type in 62% of aspirin users compare d with 76% of nonusers (P<.05). By multivariate analysis, previous asp irin use was a strong predictor of unstable angina versus myocardial i nfarction and the only independent predictor of non-Q-wave versus Q-wa ve myocardial infarction. Conclusions This study, thus, suggests a shi ft to less severe manifestation of acute coronary syndromes with aspir in use, implying that the failure of the drug in many patients with an acute coronary syndrome is only partial and that aspirin has the pote ntial of attenuating the severity of the underlying acute thrombotic d isease process.