Risk-benefit profiles of antiarrhythmic therapy

Whereas much has been learned of the mechanisms and pathophysiology of cardiac arrhythmias, treatment remains controversial and is largely empiric. Cardiac arrhythmias range in severity from innocuous to fatal; antiarrhythmic agents offer differing degrees of efficacy, inefficacy or toxicity. For an arrhythmia that needs treatment, there is no reliable or easy method for selecting the most appropriate antiarrhythmic drug. Antiarrhythmic treatment is justified for arrhythmias that are symptomatic or hemodynamically significant, the risk of lethality dictating the degree of drug toxicity that might be tolerated. The treatment of prognostically important arrhythmias is indicated if their suppression is rewarded by an improved prognosis. However, these arrhythmias are often merely indicators of a bad prognosis rather than the cause of death. Assessment of the risk-benefit ratio of antiarrhythmic treatment principally depends on the perceived risk and symptomatology of the arrhythmia and the efficacy and toxicity of the antiarrhythmic drug. Beta-adrenoceptor blocking drugs offer optimal risk-benefits for the prevention of ventricular fibrillation (infarct survivors and long QT syndrome); disopyramide and the class IC agents offer acceptable risk-benefit ratios for the treatment of ventricular tachycardia, whereas no antiarrhythmic drug offers an acceptable risk-benefit for the suppression of asymptomatic "cosmetic" atrial or ventricular ectopic beats.