Effect of nifedipine on arrhythmias in the acute phase of myocardial infarction.

In a double-blind placebo-controlled trial to study the effect of nifedipine on ventricular arrhythmias among patients with acute myocardial infarction, 434 patients with suspected myocardial infarction were randomized within 6 h from the onset of chest pain to treatment with nifedipine (p = 217) or placebo (p = 217). During the 48-h treatment period, a 10-mg capsule containing active drug or placebo was administered sublingually every 4 h for 24 h, then orally every 4 h for the next 24 h. Acute myocardial infarction was confirmed in 295 patients (146 in the nifedipine group and 149 in the placebo group). Twenty-four hour ECG tape analysis during 1-5 h from onset of chest pain showed that there was no significant difference in the number of patients with ventricular ectopics, ventricular couplets, ventricular tachycardia (3-9 beats), self terminating or sustained ventricular tachycardia between the two treatment groups. Also during the greater than 5-24 h from onset of chest pain, the numbers of patients with ventricular ectopics, multifocal, bigeminal or couplets, self-terminating ventricular tachycardia or sustained ventricular tachycardia did not differ significantly. However, there was a significant reduction in the number of patients with short runs of ventricular tachycardia (3-9 beats) in the nifedipine-treated group. There was no significant difference among patients with ventricular fibrillation between the two treatment groups.