Acute management of ventricular arrhythmias: role of antiarrhythmic agents

When treating life-threatening ventricular arrhythmias such as symptomatic ventricular tachycardia and ventricular fibrillation (VT/VF), the nature of the arrhythmia must be precisely defined and the approach must be tailored to it. For hemodynamically unstable ventricular arrhythmias, DC cardioversion or high-energy defibrillation remains the approach of choice. Determining the specific role of intravenous drugs in acute conversion of VT/VF and the most appropriate long-term therapy (pharmacologic or nonpharmacologic) to prevent recurrence can be difficult. Pharmacologic conversion of stable VT/VF presents an even greater challenge, as the role of lidocaine considered the first-line agent for many decades, is now being reevaluated. Lidocaine appears to be effective in converting no more than 20% of stable VTs, compared with 70% for intravenous sotalol. The precise efficacies of parenteral procainamide, beta-blockers, and newer class III agents, including intravenous amiodarone, remain to be defined; however, intravenous amiodarone, available recently, can control unstable, recurrent VT/VF that is resistant to lidocaine or procainamide. A standard regimen of concomitant intravenous and oral amiodarone may be given for rapid and sustained control, and allows oral amiodarone to be continued in a significant number of patients.