Outcome of myocardial infarction in patients treated with aspirin is enhanced by pre-hospital administration.

OBJECTIVE: Reducing time to reperfusion therapy is one of the goals in the management of acute myocardial infarction (AMI). We assessed the association between timing of aspirin administration and outcome of patients with AMI.

PATIENTS: We studied 922 consecutive AMI patients with ST-segment elevation in Killip class I-III on admission. Patients were divided into two groups based upon the timing of emergency aspirin administration: before (early aspirin users) or after (late aspirin users) hospital admission.

RESULTS: Early aspirin users (n = 338; 37%) were younger, less likely to be women, and more likely to smoke (p < 0.006) than late users (n = 584; 63%). Other baseline and clinical characteristics were similar. Early aspirin users were more likely to be treated with thrombolysis or primary percutaneous transluminal coronary angioplasty. Compared with late users, early aspirin users had significantly lower in-hospital complications and lower mortality rates at 7 (2.4 vs. 7.3%, p = 0.002) and 30 days (4.9 vs. 11.1%, p = 0.001). By multivariate adjustment, pre-hospital aspirin was an independent determinant of survival at 7 (odds ratio 0.43; 95% confidence interval 0.18-0.92) and at 30 days (odds ratio, 0.60; 95% confidence interval 0.32-1.08). Survival benefit associated with aspirin persisted for subgroups treated or not with reperfusion therapy.

CONCLUSIONS: Outcome of AMI patients treated with aspirin is improved by pre-hospital administration. Our findings suggest that emergency pre-hospital aspirin might facilitate early reperfusion.