Antiarrhythmic and nonantiarrhythmic drugs for sudden cardiac death prevention.

Life-threatening ventricular arrhythmias such as sustained ventricular tachycardia and ventricular fibrillation are responsible for two thirds of sudden cardiac deaths annually in the United States. Implantable cardioverter-defibrillator (ICD) therapy prevents mortality from arrhythmic death but is expensive and has some associated morbidity from proarrhythmia and mechanical malfunction. Furthermore, ICDs treat ventricular arrhythmias but do not prevent them. Antiarrhythmic drugs (AADs) can be used for acute or chronic therapy to prevent ventricular arrhythmias and sudden cardiac deaths. AADS are often used in patients with an ICD who have recurrent ICD shocks resulting from ventricular arrhythmias. Class I AADs are contraindicated in patients with structural heart disease. Other than amiodarone, all Class III drugs have either a neutral or deleterious effect on mortality. Dronedarone, a new Class III drug, may reduce mortality, but more information is needed to be sure. A class of drugs that do not qualify as an AAD can modify cardiovascular remodeling processes and have a delayed and indirect antiarrhythmic effect. These so-called "nonantiarrhythmic drugs" such as drugs acting on the renin-angiotensin-aldosterone system, fish oil, and statins can reduce the likelihood of future ventricular tachycardia/ventricular fibrillation in patients with coronary artery disease or congestive heart failure. The role of AADs for chronic therapy for primary and secondary prevention of sudden cardiac death is problematic because of proarrhythmia and adverse side effects. Because these nonantiarrhythmic drugs are well tolerated and have no proarrhythmic actions, their benefits should outweigh risks.