Treatment and prophylaxis of ventricular arrhythmias in acute myocardial infarction

Abstract

Remarkable advances have been made in the management of cardiac disease in the last 20 years, but antiarrhythmic drug strategy in the acute phase of myocardial infarction remains less than satisfactory. Primary ventricular fibrillation (VF), once considered predictable on the basis of detection of "warning arrhythmias," cannot be anticipated. Management must be either expectant or prophylactic. Restriction of drug use to selected patients and the apparent lack of effect of VF on late prognosis argue for the former approach, yet safe and effective prevention of VF is an attractive therapeutic goal. High-dose intravenous lidocaine probably offers efficacy but the risk-benefit ratio of this regimen is still debated. Adoption of a prophylactic regimen mandates drug administration to a large number of patients who either are not at risk of developing VF (noninfarct patients) or who are destined not to develop VF (70 to 95% of infarct patients). Ventricular arrhythmias other than VF are common in acute infarction and, for emotional rather than scientific reasons, often are aggressively treated. Little evidence exists to support this management. Few ventricular arrhythmias at this time in infarction have either immediate importance or prognostic significance. Reevaluation of antiarrhythmic drug use and arrhythmia treatment in acute myocardial infarction is long overdue. However, there is a paucity of controlled data upon which to base new strategies, and clinical research in this field is hampered by ethical considerations, by rigidly held but unscientifically based beliefs and by a lack of fundamental knowledge of arrhythmia mechanisms and their significance.