Prophylaxis against ventricular arrhythmias in suspected acute myocardial infarction: a comparison of tocainide and disopyramide.

Five hundred and seventy one patients admitted to a coronary care unit with suspected acute myocardial infarction were considered for entry into a double-blind study. Two hundred and eighty-three patients were excluded, mainly because of recent treatment with beta-adrenoceptor blocking agents, life threatening arrhythmias requiring specific treatment and left ventricular failure presenting with hypotension or pulmonary oedema. Two hundred and eighty-eight entered the trial of whom 202 were subsequently confirmed to have had myocardial infarction. The effects of tocainide and disopyramide on ventricular arrhythmias were compared with placebo over the first 48 h period. The three treatments were given by a combination of intravenous infusion and oral administration. The doses used were tocainide 500 mg intravenously over 30 min plus 2800 mg orally over 48 h and disopyramide 150 mg intravenously over 30 min plus 1050 mg orally over 48 h. As judged by counts of ventricular premature beats, tocainide and disopyramide exerted a similar and significant antiarrhythmic effect. The median number of ventricular premature beats over the first 24 h of treatment was 58 on placebo compared with 30 on tocainide (P less than 0.05) and 19 on disopyramide (P less than 0.05). The corresponding figures for the second 24 h were 9, 6 and 2, respectively. There were eight deaths and three episodes of ventricular fibrillation with no significant differences between the three treatment groups. Sustained ventricular tachycardia was observed in one patient in the tocainide group.(ABSTRACT TRUNCATED AT 250 WORDS)