Sudden cardiac death (SCD) affects nearly 300,000 people each year in the U.S., and out-of-hospital rates for survival range from only 2% to 25%. A substantial reduction in SCD requires primary prevention through risk-stratification and secondary prevention of sustained ventricular tachycardia (VT-S) and ventricular fibrillation (VF). Because frequent premature ventricular complexes (PVCs) appeared to be associated with an increased risk for SCD in patients with significant ventricular dysfunction, it was thought that suppression of PVCs would prevent SCD. The implantable cardioverter defibrillator (ICD) electrically treats life-threatening VT-S and VF, and it can be implanted readily in the pectoral area. Two randomized, prospective, controlled trials demonstrated conclusively that the ICD is the treatment of choice in the primary prevention of SCD in patients with a previous MI. In addition, three randomized, controlled trials found the ICD to be superior to antiarrhythmic drugs in the secondary prevention of SCD. Physicians should learn to recognize patients who are candidates for the ICD and refer them to an electrophysiologist so that they can get this life-saving therapy