Antiarrhythmic treatment of patients with left ventricular dysfunction

The treatment of arrhythmias with antiarrhythmic agents in patients with depressed left ventricular function and congestive heart failure (CHF) creates certain dilemmas for the clinician. First, the association of frequent PVCs and/or nonsustained ventricular tachycardia (VT) in patients with CHF is associated with an increased risk of sudden cardiac death. Two examples of this association are in patients with chronic CHF or in the postmyocardial infarction setting. Given a higher risk of sudden cardiac death, the necessity of proper treatment to alter this prognosis takes on enhanced importance. Second, drugs appear to be less effective in controlling arrhythmias in the presence of a depressed ejection fraction. Thus, in this high risk group of patients who need antiarrhythmic treatment, identifying a proper drug is more difficult. Third, although the prognosis of the above patients is poor, little data exist to support the concept that antiarrhythmic therapy may alter this otherwise dismal prognosis. Fourth, there is a greater potential for adverse effects in this setting. With all drugs, the risk of proarrhythmia and CHF exacerbation is higher. Therefore, antiarrhythmic drugs with more benign proarrhythmic profiles and better hemodynamic profiles should be considered as front-line therapy in these patients. Finally, altered pharmacokinetics are commonly noted in this patient group. Reduced volumes of distribution may increase blood levels and decreased hepatic or renal clearance may prolong the half-life of a given drug. These pharmacokinetic principles should be considered since they may require alteration of dosing to avoid toxic levels of a given antiarrhythmic drug. Proper consideration of the above problems may lead to better antiarrhythmic drug selection in arrhythmia patients with concomitant CHF.