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NIH Research Matters

January 13, 2013

Implanted Defibrillators Boost "Real World" Survival

A new study found that implanted cardiac devices are linked to improved survival rates, whether or not patients were participating in a carefully controlled clinical trial.

Photo of electrocardiogram showing a heart pulse.

Implantable cardioverter-defibrillators (ICDs) can save the lives of patients with heart failure. This small device is placed in the chest. It monitors heartbeats and delivers electrical pulses if dangerous rhythms (arrhythmias) are detected. These pulses can normalize the heartbeat to prevent sudden cardiac arrest and death.

Earlier clinical trials showed that ICDs can lengthen patient survival compared to optimal medical therapy. But it was unclear if the benefits seen in highly controlled clinical trials would hold true in real-world settings. Randomized clinical trials usually enroll patients with fewer co-existing medical conditions. Participants are also often treated and closely monitored by skilled specialists. People under typical medical care might not receive such benefits from ICDs.

Dr. Sana M. Al-Khatib and colleagues at the Duke Clinical Research Institute compared outcomes in real-world patients with ICDs to similar patients in clinical trials. For regular patients, the scientists drew on data from the nation’s largest registry of ICD implants. The ICD Registry includes information on all Medicare patients who received an ICD since 2005 for “primary prevention.” These patients are at high risk for sudden cardiac arrest but have not yet had an episode. The analysis was funded by NIH’s National Heart, Lung and Blood Institute (NHLBI).

As reported in the January 2, 2013, issue of the Journal of the American Medical Association, the scientists studied a subset of more than 5,000 ICD Registry patients who were matched to similar participants in 2 already-completed clinical trials. The researchers found no significant difference in survival between those who received ICD implants in the trials or in the ICD Registry. In one trial, the 2-year mortality rate was 13.9% for real-world patients and 15.6% for matched study participants receiving an ICD. In the other trial, which was funded by NHLBI, 3-year mortality rates were 17.3% for registry patients and 17.4% for trial ICD recipients.

The researchers also found that matched ICD recipients in the real-world registry had significantly greater survival than trial participants who received only standard medical therapy.

These results show similar survival rates for real-world and clinical trial participants. But the researchers note that their analysis looked only at carefully matched patient populations. Further research and data would be needed to assess whether patients who are significantly older and sicker than those studied here would also benefit from ICDs.

"Even without those data, however, our study gives patients and their health care providers reassurance that what we have been doing in clinical practice has been helpful, and is improving patient outcomes,” Al-Khatib says. “Our findings support the continued use of this life-saving therapy in clinical practice.”

—by Vicki Contie

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Reference: JAMA.2013 Jan 2;309(1):55-62. doi: 10.1001/jama.2012.157182. PMID: 23280225.

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Editor: Harrison Wein, Ph.D.
Assistant Editors: Vicki Contie, Carol Torgan, Ph.D.

NIH Research Matters is a weekly update of NIH research highlights from the Office of Communications and Public Liaison, Office of the Director, National Institutes of Health.

This page last reviewed on January 11, 2013

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