Lidocaine prophylaxis in acute myocardial infarction.

The prophylactic administration of lidocaine for the prevention of primary ventricular fibrillation (VF) following suspected acute myocardial infarction (MI) is controversial. The incidence of primary VF following acute MI ranges from 1.8% to 10.5%. "Warning arrhythmias" have not been shown to be reliable predictors of VF. In-hospital prophylactic administration of lidocaine has been shown to decrease the incidence of primary VF, whereas prehospital administration has not. However, prophylactic administration of lidocaine has not been shown to have a beneficial effect on mortality and may in fact increase mortality. The incidence of lidocaine-induced adverse effects during prophylaxis ranges from 4% to 85%, with an average of approximately 35%. In view of the low incidence of primary VF following acute MI, the high incidence of lidocaine-induced adverse effects, and the lack of evidence of beneficial effect on mortality, prophylactic lidocaine administration to all patients with suspected MI is not recommended. The American Heart Association and American College of Cardiology recommend prophylactic lidocaine administration in patients with acute myocardial ischemia or MI who have ventricular premature beats that occur frequently (greater than 6 per minute), are closely coupled (R on T), multiform in configuration, or occur in short bursts of three or more in succession.