Influence of prehospital administration of aspirin and heparin on initial patency of the infarct-related artery in patients with acute ST elevation myocardial infarction

OBJECTIVES: The aim of this study was to investigate the influence of prehospital administration of aspirin and heparin on the initial patency of the infarct-related artery (IRA) in patients with acute myocardial infarction (MI). BACKGROUND: Prehospital diagnosis of acute MI facilitates early pharmacologic intervention on the way to the catheterization laboratory for primary angioplasty. METHODS: We studied the angiographic data and 30-day clinical outcome of 1,702 patients treated with primary angioplasty; 860 received aspirin and heparin before transportation to our hospital and 842 received aspirin and heparin in our hospital. RESULTS: The Thrombolysis In Myocardial Infarction (TIMI) 2 or 3 flow in the IRA was higher in the prehospital treated group (31% vs. 20%, relative risk 0.65, 95% confidence interval 0.55 to 0.78, p < 0.001). Patients with TIMI 2 or 3 flow on the initial angiogram had a higher angioplasty success rate (94% vs. 89%, p < 0.001), a smaller enzymatic infarct size, a higher left ventricular ejection fraction and a lower 30-day mortality (1.6% vs. 3.4%, p = 0.04). CONCLUSIONS: Prehospital administration of aspirin and heparin results in a higher initial patency of the IRA in patients with acute MI.