Survival rates similar for ICD patients in clinical trials vs. clinical practice

Survival rates did not differ significantly between clinical trial patients with an implantable cardioverter defibrillator and those who received the device in clinical practice, investigators reported in JAMA. These findings support the continued use of primary prevention ICDs for use in a clinical setting, they said.

Investigators set out to determine the survival-rate difference between trial-eligible patients with a primary prevention ICD and similar patients who received an ICD in a clinical setting. They used data from the two largest primary prevention clinical trials in the United States, MADIT-II and SCD-HeFT, and a large national registry of patients who received a primary prevention ICD in a clinical setting for the analysis.

"The implantable cardioverter-defibrillator is a highly effective therapy for preventing sudden cardiac death in patients with heart failure. However, the outcomes of this therapy in routine clinical practices are largely uncertain. Because randomized clinical trials generally enroll patients with fewer comorbidities and are usually conducted in highly controlled and monitored settings, the results of the primary prevention ICD trials may not be generalizable to routine clinical practice," Sana M. Al-Khatib, MD, MS, from the Duke Clinical Research Institute, Durham, N.C., and colleagues wrote in the study.

Analysis of the data indicated there was no significant difference in survival between MADIT-II-like patients in the National Cardiovascular Data Registry ICD Registry and patients randomly assigned to receive an ICD in the MADIT-II trial (2-year mortality rates: 13.9% vs. 15.6%). The survival rate of MADIT-II-like patients in the ICD Registry was significantly better than the survival of MADIT-II patients assigned to receive medical therapy (2-year mortality rates: 13.9% vs. 22%).

There was no significant survival difference between SCD-HeFT-like patients in the ICD registry and patients randomly assigned to receive ICD therapy in SCD-HeFT (3-year mortality rates: 17.3% vs. 17.4%). The survival of SCD-HeFT-like patients in the ICD Registry was also significantly better than the survival of SCD-HeFT patients assigned to placebo (3-year mortality rates: 17.3% vs. 22.4%).

"Using the largest registry of ICD implants in the United States, we demonstrated that survival among MADIT-II-like and SCD-HeFT-like patients who received a primary prevention ICD in clinical practice was not significantly different from survival among patients who received an ICD in those major primary prevention ICD trials but was significantly greater than trial patients randomized to receive medical therapy," researchers reported in the study. "These findings were observed in the overall studied population as well as in patients aged 65 and older."

For more information:

Khatib-Al SM. JAMA. 2013;309:55-62.

Disclosure:The researchers report receiving a grant from the National Heart, Lung, and Blood Institute.