ICDs: Real World Life Savers

Implantable cardioverter defibrillator patients not in a clinical trial as likely to survive as those in a trial

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) Implanted heart devices have generally fared well in studies. But does that mean it will give everyday Joes a heart boost and added longevity? The latest findings suggest they do.

When it comes to implantable cardioverter-defibrillators (ICDs), investigators have found that real world patients are surviving at the same rates previously found in clinical trials.

An ICD is an implanted device that helps prevent sudden cardiac death in patients with a heart arrhythmia. They are also at times used to provide pacing for congestive heart failure patients.

"Discuss heart failure treatment options with your cardiologist."

Sana M. Al-Khatib, MD, MHS, a lead researcher from the Duke Clinical Research Institute, examined previous clinical trials of heart failure patients that received ICDs as compared to patients treated in clinical practice. He did not find a significant difference in survival between the two groups.

The results are significant because trial findings do not always represent the benefits that the average patient will reap. That's because studies include highly controlled settings and only specific types of patients.

Researchers reviewed the National Cardiovascular Data Registry, following heart failure patients who received an ICD between January 2006 and December 2007. Those survival rates were compared to patients in two clinical trials that followed heart failure patients with ICDs. The reviewed studies included MADIT-II, which followed 742 patients and SCD-HeFT, which had enrolled 829 individuals.

Investigators used 2,464 matched patients with similar criteria from the national registry to compare to those who participated in the MADIT-II study, and 3,352 matched patients to compare against participants of the SCD-HeFT trial. However, individuals from the registry, or the "real world patients" were significantly older and tended to have other medical conditions in addition to the heart failure.

Average follow-up time for the MADIT-II study was 20 months compared to 46 months for the SCD-HeFT trial and 36 months among patients in the US registry.

When matched ICD registry patients were compared to MADIT-II participants randomly assigned to receive an ICD, researchers did not find a significant difference in survival. Two years after receiving an ICD, 14 percent of registry patients had died versus nearly 16 percent of study patients. Among the MADIT-II study patients assigned to medical therapy, 22 percent died.

At the 3-year mark, registry-matched patients also fared as well as SCD-HeFT participants who received an ICD, with 17 percent from each group surviving. Among the SCD-HeFT participants who received an inactive drug, 22 percent died.

Dr. Al-Khatib noted it can be difficult to generalize study findings to the general population. Real-world patients may not get the same care as highly-monitored study participants, and other factors such as additional medical conditions and age can play a role.

Investigators indicated that the findings support the continued use of ICDs for heart failure patients in clinical practice.

The study, funded by a grant from the National Heart, Lung, and Blood Institute, was recently published in the Journal of the American Medical Association.

Reviewed by: 
Review Date: 
January 2, 2013
Last Updated:
January 6, 2013