Role of Implantable Cardioverter Defibrillators in Dilated Cardiomyopathy

Abstract

ICDs in Dilated Cardiomyopathy. Idiopathic dilated cardiomyopathy (DCM) accounts for about 10,000 deaths per year in western countries. Of these deaths, 8% to 51% occur suddenly, with more than half of the events due to a ventricular arrhythmia. Improvement in diagnostic techniques and therapeutic strategies, together with changes in secular trends, have likely contributed to the reported trend toward improved survival in recent years. Identification of DCM patients at higher risk of sudden death is difficult. Poor left ventricular function is the strongest predictor of all‐cause death, whereas a history of sustained unstable ventricular arrhythmia or cardiac arrest identifies patients at high risk of sudden death. Recent data suggest that a history of syncope, regardless of inducibility at programmed electrical stimulation, may be a risk factor of sudden death. Despite the absence of controlled studies, use of implantable cardioverter defibrillator therapy for primary prevention can be considered in patients with unexplained syncope as well as subgroups of DCM patients awaiting transplantation. In patients who survive a cardiac arrest or an unstable ventricular tachycardia, use of implantable cardioverter defibrillator therapy is associated with improved survival during follow‐up and should be considered as a first‐line therapy.

Syncope Predicts the Outcome of Cardiomyopathy Patients

“…Retrospective data suggest that patients with syncope and cardiomyopathy who undergo ICD implantation, whether or not they have a positive electrophysiology test, get appropriate ICD activations (9,14,15) and that this may reduce the risk of death (16 -18), although the data on this are not definitive and the risk of death remains high (12,19). Therefore, ICDs have been recommended in heart failure patients with syncope (7,20). Data regarding syncope in patients with congestive heart failure are based largely on small single-site studies of highly select patients who often are not treated with standard medical therapy for heart failure.…”

<b>Carvedilol Prevents Myocardial Fibrosis in Hamsters</b>

“…Since 50% of patients with cardiomyopathy generally die suddenly, 19,20) there is a high incidence of fatal arrhythmias. Therefore, we assumed that the hamsters with cardiomyopathy may have died suddenly due to arrhythmias that are frequently associated with the progression of cardiomyopathy.…”

Ventricular Arrhythmia Inducibility Predicts Subsequent ICD Activation in Nonischemic Cardiomyopathy Patients: A DEFINITE Substudy

“…Nonischemic dilated cardiomyopathy is believed to account for about 10,000 yearly deaths between the United States and Europe with up to one‐half of those deaths occurring suddenly 11 . Prevention of sudden death in nonischemic cardiomyopathy had been unsuccessful until recent randomized clinical trials demonstrated the benefit of the ICD 1–3 .…”