Prophylactic lidocaine in suspected acute myocardial infarction.

The incidence of serious ventricular arrhythmias following acute myocardial infarction is highest during the first few hours after injury, and thereafter declines. Several investigations into the prophylactic use of lidocaine to prevent the development of arrhythmias have shown that lidocaine, given in therapeutic doses, is effective in preventing ventricular fibrillation and in reducing early mortality. Lidocaine was found to be effective when given either by the intravenous or by the intramuscular routes. The recommended dosage is 100 mg given as an intravenous bolus followed by 2 to 4 mg/min as an infusion, which should be given by infusion pump. Another recommendation is to use two 100 mg boluses 20 minutes apart, along with the same infusion. We recommend that lidocaine be started as soon as possible in all patients suspected of having suffered acute myocardial infarction.