Sudden cardiac death syndrome: diagnosis and management

Sudden cardiac death (SCD) can be caused by a variety of cardiac and noncardiac disorders. The diagnostic work-up includes detailed history, physical examination, electrocardiography (ECG), chemistry panel, 24-hour Holter ECG recording, and echocardiography. In selected patients, treadmill-exercise testing, electrophysiologic study, cardiac catheterization with coronary angiography, magnetic resonance imaging, and endomyocardial biopsy are performed. The treatment strategy is rationalized according to the underlying disorder and clinical presentation. Correction of reversible causes such as hypoxia, myocardial ischemia, electrolyte imbalance, congestive heart failure, and proarrhythmic effects of drugs is essential. In patients with arteriosclerotic heart disease, coronary revascularization, using percutaneous coronary angioplasty with stenting or aortocoronary bypass grafting, and optimization of hemodynamics are often necessary. For survivors of SCD syndrome (secondary prevention), implantation of a cardioverter/defibrillator (ICD) is the treatment of choice, with or without adjunct antiarrhythmic drug therapy. Reduction of the sympathetic influence such as with beta-adrenergic blockade and control of hypertension or congestive heart failure may abate the triggering mechanism, thereby reducing the rate of arrhythmia reemergence. Because of the ease of the implantation technique and refined programmability, the current trend is to apply ICD therapy in patients deemed at high risk of SCD, with the aim of primary prevention.