Nifedipine therapy for patients with threatened and acute myocardial infarction: a randomized, double-blind, placebo-controlled comparison.

Abstract

Preliminary clinical and laboratory observations suggest that nifedipine prevents progression of threatened myocardial infarction by reserving coronary spasm or might limit necrosis during the course of acute myocardial infarction. Patients [3143] with ischemic pain of > 45 min duration were screened and 105 eligible patients with threatened myocardial infarction and 66 with acute myocardial infarction were randomly assigned to receive nifedipine (20 mg orally every 4 h for 14 days) or placebo plus standard care. Treatment was started 4.6 .+-. 0.1 h after the onset of pain. Infarct size index was calculated by the MB-creatine kinase (CK) method and expressed as CK-geq/m2 .+-. SE. The incidence of progression to infarction among patients with threatened myocardial infarction was not significantly altered by nifedipine (36 of 48 [75%] for placebo-treated and 43 of 57 [75] for nifedipine-treated patients). Infarct size index was similar among placebo- and nifedipine-treated patients (16.9 .+-. 1.5 MB-CK-geq/m2, n = 65, and 17.0 .+-. 1.5 MB-CK-geq/m2, n = 68, respectively) with threatened myocardial infarction who exhibited infarction and for those with acute myocardial infarction. Among the 171 eligible patients randomly assigned to drug or placebo, 6 mo. mortality did not differ significantly (8.5% for placebo vs. 10.1% for nifedipine, NS), but mortality in the 2 wk after randomization was significantly higher for nifedipine-treated patients (0% for placebo compared with 7.9% for nifedipine, P = 0.018). There were no significant differences in 2 wk and 6 mo. mortalities in the group of all participating patients, which included 10 patients randomly assigned therapy but retrospectively determined to be ineligible. Two wk mortality for this group (n = 181) was 2.3% for placebo- and 7.5% for nifedipine-treated patients and 6 mo. mortality was 11.4% for placebo- and 10.8% for nifedipine-treated patients. Nifedipine therapy did not prevent progression of threatened myocardial infarction to the acute event or limit infarct size in patients who experienced infarction. There was a statistically significant increase in 2 wk mortality with nifedipine in the group of eligible patients randomly assigned to a regimen, but mortality was balanced when results were analyzed for all patients taking part in the randomization protocol.