Recent aspirin use is associated with smaller myocardial infarct size and lower likelihood of Q-wave infarction, ,

Background Controversy exists about the effect of recent aspirin use on infarct size and the likelihood of Q-wave infarction in patients who sustain myocardial infarction. Methods We performed face-to-face interviews and chart reviews on 3665 patients with acute myocardial infarction for the Determinants of Myocardial Infarction Onset Study. For the 2206 patients who did not receive thrombolytic therapy, we assessed aspirin use, peak creatine kinase levels (in 1043 patients), and electrocardiographic interpretations (in 1447 patients). Results Of the initial 1043 patients, 317 (30.3%) subjects reported aspirin use in the 4 days before their infarction. The mean ± SD peak creatine kinase level for aspirin users was 701 ± 570 IU/mL versus 851 ± 727 IU/mL for nonusers, an 18% difference (95% confidence interval [CI], 8% to 26%; P < .001). After adjustment for confounding factors, the difference was 12% (95% CI, 2% to 21%; P = .03). Similarly, 38.9% of the aspirin users and 48.7% of the nonusers sustained a Q-wave infarction, an odds ratio of 0.67 (95% CI, 0.54 to 0.83, P < .001). The adjusted odds ratio was 0.77 (95% CI, 0.61 to 0.97, P = .03). Conclusions Recent aspirin use was associated with smaller infarct size and fewer Q-wave infarctions among this population of early survivors of acute myocardial infarction who did not receive thrombolytic therapy. (Am Heart J 1999;137:1120-8.)