Characterization and clinical course of patients not receiving aspirin foracute myocardial infarction: Results from the MITRA and MIR studies

Background Clinical trials have shown the efficacy of aspirin for acute myo cardial infarction (AMI). However, not all patients receive aspirin for AMI . The aim of this study was to provide information on characteristics and c linical course of patients not treated with aspirin for AMI. Methods We analyzed the data of the Myocardial Infarction Registry (MIR) an d the Maximal individual Therapy of Acute Myocardial Infarction (MITRA) reg istry. MITRA and MIR were prospective multicenter registries of patients wi th ST segment elevation myocardial infarction in Germany. Results of 22,572 patients registered from 1994 to 1998, 1767 (7.8%) did no t receive aspirin within the First 48 hours after admission. Multivariate a nalysis revealed two main factors associated with withholding aspirin for A MI: relative contraindications to aspirin (gastric ulcer [odds ratio (OR) 4 .9, 95% confidence interval (CI) 3.7-5.7], renal insufficiency [OR 1.4, 95% CI 1.1-1.8]), and critical clinical state at admission (cardiogenic shock EOR 1.5, 95% CI 1.2-2.1] and prehospital resuscitation [OR 1.8, 95% CI 1.4- 2.2]). In addition, these patients were significantly less likely to receiv e reperfusion therapy and adjunctive medical therapy such as beta -blockers and angiotensin-converting enzyme inhibitors. In-hospital mortality after adjustment for baseline characteristics was 27.2% in patients without aspir in compared with 11.1% in patients treated with aspirin. Conclusions only a minority of AMI patients (7.8%) did not receive aspirin. Relative contraindications to aspirin and a critical clinical state at adm ission were the main factors associated with withholding aspirin for AMI. E ven after adjustment for patient characteristics, the mortality of patients without aspirin was almost three times higher.