Single-lead ICD Extends Life in Patients with CHF

Single-lead ICD Extends Life in Patients with CHF

By Wayne Kuznar

A single-lead, shock-only implantable cardioverter—defibrillator (ICD) reduces the risk of death by about 25% in patients with moderate-to-severe congestive heart failure (CHF) and left ventricular (LV) dysfunction.

Data from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) show that the ICD reduced mortality in patients with CHF of either ischemic or nonischemic origin. This was in stark contrast to the antiarrhythmic amiodarone (Pacerone), which did not reduce mortality. The findings were published in The New England Journal of Medicine (2005;352:225-237).

In SCD-HeFT, 2521 patients with New York Heart Association class II or III CHF and an ejection fraction (EF) £35% were randomized to 1 of 3 treatment arms: conservatively programmed shock-only ICD therapy (n = 829), amiodarone (n = 845), or placebo (n = 847). A nearly equal number of patients with CHF of ischemic and nonischemic origin (52% vs 48%, respectively) were enrolled. All patients were also receiving conventional CHF drug therapy.

After a median follow-up of 45.5 months, the mortality rates were 29% among the placebo recipients and 22% among the ICD recipients—a 23% relative risk reduction (P = .007) with ICD implantation. In contrast, amiodarone offered no protection against death (mortality rate, 28%) compared with placebo. The survival advantage associated with ICD implantation was not dependent on the CHF etiology.

In an accompanying editorial (pages: 285-287), Alan Kadish, MD, wrote that ICD therapy for the primary prevention of sudden death in patients with LV dysfunction “should be considered a long-term rather than a short-term intervention.” In a perspective article in that issue (pages 222-224), Drs McClleland and Tunis, of the Center for Medicare and Medicaid Services, announced that these results would likely lead to an expansion of ICD coverage to patients with CHF and EF £35%. Previously, Medicare limited coverage to patients who already experienced potentially fatal ventricular arrhythmias.

Subgroup analysis showed patients with class III heart failure did not have significant benefit from ICD therapy; however, drawing conclusions from subgroup analysis is dangerous especially since the study was not powered to explore differences in outcomes based on functional class, said coinvestigator Jeanne Poole, MD, associate professor of medicine, and director of the electrophysiology service, division of cardiology, University of Washington, Seattle.

Previously, DEFINITE (Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation), conducted in CHF patients with nonischemic cardiomyopathy, showed a strong trend, but no statistical significance, toward benefit with ICD (P = .08). In DEFINITE, patients with class III derived the greatest survival benefit from ICD therapy.

Dr Poole noted that SCD-HeFT was “designed to be as simple as possible to reduce risks and costs, and that is why a single-lead ICD was chosen,” hence these results apply to a single-lead ICD only. The message from SCD-HeFT is that the single-lead ICD is sufficient to prevent excess mortality in high-risk patients, she said.

At the 2004 annual meeting of the American Heart Association, a previous analysis of data from SCD-HeFT showed that shock-only ICD therapy is cost-effective in the primary prevention of sudden cardiac death in patients with stable, moderate HF.

According to Daniel Mark, MD, MPH, director of outcomes research, Duke Clinical Research Institute, Durham, NC, and lead investigator of the study, ICD shock-only therapy is “an economically attractive way to improve the health benefits of society” when used for patients with stable HF. The cost was within the $50,000 per life-year saved that is considered to be economically acceptable, a cost level consistent with Medicare reimbursement for dialysis in patients with end-stage renal failure, said Dr Mark.