Primary prevention of sudden death using ICD therapy: incremental steps.

Ever since its development by Dr. Michel Mirowski in the 1970s and its use in clinical practice in 1980, the implantable cardioverter-defibrillator (ICD) has improved survival in patients presenting with sustained ventricular tachycardia and ventricular fibrillation. Three recent randomized studies—Antiarrhythmic Drugs versus Implantable Defibrillator (AVID) (1), Canadian Implantable Defibrillator Study (CIDS) (2) and Cardiac Arrest Study Hamburg (CASH) (3)—have demonstrated that the ICD is superior to the best antiarrhythmic therapy in the prevention of death in patients who have already experienced an episode of sustained tachycardia arrhythmia. Although sub-analysis of AVID and CIDS data has suggested that antiarrhythmic drug therapy may be as good as ICD therapy in patients with relatively well-preserved ventricular function, this result remains to be confirmed prospectively (4), and ICD therapy remains the most efficacious therapy in the secondary prevention of sudden death (SD). However, because only a small percentage of patients who suffer a cardiac arrest in the U.S. each year survive to benefit from ICD therapy as secondary prevention, the use of the ICD for the primary prevention of SD has received increasing attention.