Prophylaxis of primary ventricular fibrillation in acute myocardial infarction. The case against lignocaine.

Ventricular fibrillation is the most important arrhythmic complication of acute myocardial infarc- tion and accounts for the majority of deaths in the 15300/o of patients with infarction who die in the first hour after the onset of symptoms.' In the coronary care unit ventricular fibrillation occurs in 3-10% of patients with myocardial infarction2 and would be seen more frequently if the time delay from the onset of symptoms to admission to the coronary care unit were reduced since the incidence of primary ventricu- lar fibrillation falls almost exponentially after the first few hours of infarction.3-5 The prevention of primary ventricular fibrillation may be viewed as an important goal in the coronary care unit, particularly if the time delay to hospital admission can be reduced. The most widely studied agent in the prophylaxis of this arrhythmia has been lignocaine, but despite numerous reports considerable controversy still surrounds its use. There are two fun- damental questions: (a) Is lignocaine effective at pre- venting primary ventricular fibrillation or its recur- rence? (b) Should it be used routinely for these pur- poses? Although several recent editorials6 7 and reviews289 have recommended the use of routine prophylactic lignocaine, its current role in the coro- nary care unit has evolved in part through emotive argument not always scientifically based. A critical review of the subject appears to be warranted.