Quinidine for Prophylaxis of Arrhythmias in Acute Myocardial Infarction

Abstract The efficacy of quinidine therapy for the prevention of cardiac arrhythmias was determined in a prospective controlled clinical trial involving 53 patients with uncomplicated acute myocardial infarction. After a loading procedure, 300 mg of quinidine sulfate or placebo was administered orally every six hours for five days under balanced, random, double-blind conditions. An automated arrhythmia detection system was used to quantify arrhythmias from stored continuous electrocardiographic tape recordings. By the sixth hour of therapy quinidine-treated patients demonstrated a 50 per cent reduction (p less than 0.001) in ventricular and supraventricular premature contractions, a 33 per cent lowered incidence (p less than 0.05) of serious ventricular arrhythmias and a blood quinidine level of 2.5 ± 0.3 (mean ± S.E.M.) mg per liter. One patient died in each treatment group. Mild adverse reactions to quinidine were observed in only two patients. Quinidine at a dosage producing modest blood concentration ...