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 (TTMT) 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. (C) 2002 by the American College of Cardiology Foundation.