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Aspirin Before Thrombolysis May Improve Survival After MI

Kate Traynor

Taking aspirin before, rather than after, receipt of a thrombolytic agent seems to improve a patient's likelihood of surviving an acute myocardial infarction, say researchers in Israel.

The researchers based their findings on an analysis of data from a previously concluded investigation, the second Argatroban in Acute Myocardial Infarction (ARGAMI-2) study. The findings of the follow-up analysis appear in the Feb. 15 American Journal of Cardiology.

During the first week after a myocardial infarction, 2.5 percent of the patients who received an aspirin dose before the thrombolytic drug died, as did 6.0 percent of those who received the clot buster first. By the thirtieth day after treatment, 3.3 percent of the patients in the aspirin-first group and 7.3 percent of those who took aspirin after thrombolysis therapy started—the so-called late-aspirin group—had died.

The survival difference was still evident one year after the myocardial infarction: 5.0 percent of the patients in the aspirin-first group and 10.6 percent of those in the late-aspirin group had died.

In all, 1,200 patients at 25 medical centers in Israel participated in the 15-month ARGAMI-2 study. The study was conducted to compare the effectiveness of argatroban and heparin as adjuncts to tissue plasminogen activator or streptokinase therapy within the first six hours after the onset of symptoms of an acute myocardial infarction. All ARGAMI-2 enrollees had been slated to take 160 mg of aspirin within an hour after the start of thrombolytic therapy and continue aspirin therapy for 30 days, but the timing of the first aspirin dose was not the focus of the original study.

A total of 364 study participants took the aspirin dose before the infusion of clot buster began, and the rest of the patients received the drugs in the reverse order. Nineteen percent of the study participants were already taking aspirin before enrolling in the study, a usage rate the researchers described as "relatively low." Significantly more people in the late-aspirin group than in the aspirin-first group were using aspirin at baseline.

Half of the people in the aspirin-first group took aspirin within 1.6 hours after the onset of chest pain. Of the 809 patients in the late-aspirin group for whom detailed information was available, half had taken aspirin within 3.5 hours of symptom onset.

Within the first month after treatment for the myocardial infarction, recurrent ischemia was more common in the aspirin-first group than in the late-aspirin group. People in the aspirin-first group were also more likely than the other patients to undergo coronary angiography or have bypass surgery or angioplasty.

Aspirin-first patients who had coronary artery bypass grafting or angioplasty within a month after initial treatment for the myocardial infarction had a higher one-year survival rate than did late-aspirin patients who underwent these revascularization procedures. Survival rates at seven and 30 days were similar for all of the patients who underwent revascularization within 30 days after the myocardial infarction. But the seven-day, 30-day, and one-year survival rates were about twice as high in the aspirin-first group than in the late-aspirin group for patients who did not undergo a revascularization procedure in the first 30 days after the myocardial infarction.