Indications for ICD and cardiac resynchronization therapy for prevention of sudden cardiac death.

The implantable cardioverter-defibrillator (ICD) is used for primary and secondary prophylaxis of sudden cardiac death in high-risk patients. While several trials have demonstrated the superiority of ICD over standard medical therapy or antiarrhythmic medication in this population, a few trials have not shown survival benefit. The Multicenter Automatic Defibrillator Implant Trial II study revealed that ICD reduces mortality in patients with ischemic cardiomyopathy. The Sudden Cardiac Death-Heart Failure Trial demonstrated that the ICD prevents sudden cardiac death and all-cause mortality in high-risk patients with moderate ischemic and nonischemic cardiomyopathy and heart failure. The ICD is also recommended for high-risk patients with inherited arrhythmia or cardiomyopathy. Cardiac resynchronization therapy reduces mortality and heart failure class as compared with optimal medical therapy in advanced heart failure. The high economic cost of widespread ICD use must also be considered. Therefore, it is prudent to identify a high-risk population who will benefit most from these devices.