Combination drug therapy for ventricular arrhythmias.

The role of drug combinations for the treatment of patients with ventricular arrhythmias is reviewed. The use of single drugs to suppress ventricular arrhythmias is often unsatisfactory; a drug may be ineffective or cause intolerable adverse effects. Simultaneous use of antiarrhythmic agents with different but compatible electrophysiologic effects may control arrhythmias refractory to single-drug therapy. Patients may tolerate combination therapy fairly well because dosages in combination therapy are often lower than those employed when either drug is used alone. Although comparison of drug trials is hampered by nonuniformity among study protocols, the data suggest that drug combinations can be effective in treating some patients. Pairs of drugs showing the most promise have been a class IA drug (procainamide, quinidine, or disopyramide) with a class IB drug (usually mexiletine), and a class IA drug with a beta blocker. Amiodarone should be combined with a class I drug only as a last resort. There is little evidence to support the simultaneous use of two class IA drugs. Selection of a drug combination should be guided by consideration of the patient's medical history, concurrent disease states, and risk of sudden cardiac death. The efficacy of combination therapy should be evaluated by electrophysiologic testing or ambulatory electrocardiography. Combination antiarrhythmic therapy should be reserved for patients in whom single-drug therapy has been ineffective or poorly tolerated. More studies are needed to further define the efficacy, safety, and role of drug combinations in the treatment of ventricular arrhythmias.