Treatment of cardiac arrhythmias in patients with acute myocardial infarction.

Cardiac arrhythmias and conduction disturbances are commonly observed in patients with myocardial infarction. The available data suggest the administration of prophylactic lidocaine, either through a large intramuscular dose (300 mg), which is particularly suited for out-patient situations, or through intravenous loading doses followed by a constant lidocaine infusion. Patients with ventricular arrhythmia should be treated with direct-current countershock if hemodynamic deterioration is present. Drug therapy for patients with ventricular arrhythmias who are resistant to lidocaine include procainamide, bretylium, or intravenous amiodarone (experimental drug). Treatment of atrioventricular block in acute infarction depends on the site of atrioventricular block, the infarct location, and the hemodynamic status. Generally, atrioventricular block associated with inferior infarction and normal hemodynamic states generally does require insertion of a pacemaker. In contrast, patients with anterior myocardial infarction and Mobitz II or third degree atrioventricular block should be treated with emergent temporary insertion of a pacemaker. In addition, prophylactic pacing is clearly indicated for those with acute myocardial infarction complicated by the bifascicular block pattern of first degree atrioventricular block and new onset bundle branch block.