Usefulness of antithrombotic therapy in resting angina pectoris or non-Q-wave myocardial infarction in preventing death and myocardial infarction (a pilot study from the antithrombotic therapy in acute coronary syndromes study group)

In a prospective pilot trial of antithrombotic therapy in the acute coronary syndromes (ATACS) of resting and unstable angina pectoris or non-Q-wave myocardial infarction, 3 different antithrombotic regimens in the prevention of recurrent ischemic events were compared for efficacy. Ninety-three patients were randomized to receive aspirin (325 mg/day), or full-dose heparin followed by warfarin, or the combination of aspirin (80 mg/day) plus heparin and then warfarin. Trial antithrombotic therapy was added to standardized antianginal medication and continued for 3 months or until an end point was reached. Analysis, by intention-to-treat, of the 3-month end points, revealed the following: recurrent ischemia occurred in 7 patients (22%) after aspirin, in 6 patients (25%) after heparin and warfarin, and in 16 patients (43%) after aspirin combined with heparin and then warfarin; coronary revascularization occurred in 12 patients (38%) after aspirin, in 12 patients (50%) after heparin and warfarin, and in 22 patients (60%) after aspirin combined with heparin and then warfarin; myocardial infarction occurred in 1 patient (3%) after aspirin, n 3 patients (13%) after heparin and warfarin, and in no patient after aspirin combined with heparin and then warfarin; no deaths occurred after aspirin or after aspirin combined with heparin and then warfarin, but 1 patient (4%) died after warfarin alone; major bleeding occurred in 3 patients (9%) after aspirin, in 2 patients (8%) after heparin and warfarin, and in 3 patients (8%) after aspirin combined with heparin and then warfarin. Recurrent myocardial ischemia occurred at 3 ± 3 days after randomization. In those who had coronary angioplasty or bypass surgery, revascularization was performed at 6 ± 4 days. During trial therapy, no patient died, had a Q-wave myocardial infarction or a major bleed. Most bleeding complications consisted of blood transfusions during or immediately after bypass surgery. Only 25% of patients enrolled were discharged on trial therapy because of revascularization and withdrawals. Thus, irrespective of the antithrombotic regimen used, and even with aggressive combination therapy, a substantial fraction of patients with unstable angina or non-Q-wave myocardial infarction have recurrent myocardial ischemia and are referred for coronary revascularization. Antithrombotic therapy, coupled with early intervention after recurring ischemia, was associated with a low rate of death or myocardial infarction within the first 3 months.