Costlier Heart Device May Not Be Worth It, Study Suggests

Dual-chamber implanted defibrillators had more complications than single-chamber models

By Brenda Goodman

HealthDay Reporter

TUESDAY, May 14 (HealthDay News) -- Patients prone to dangerously fast heart rhythms may get just as much help and have fewer complications with less-expensive implanted defibrillators that run one wire to the heart instead of two, a new study shows.

Implantable cardioverter defibrillators, or ICDs, are like having an emergency "crash cart" in the chest. The devices can sense runaway heart rhythms and deliver powerful shocks to jolt the heart back to a normal, steady pace.

Studies have shown that the devices cut deaths in patients at risk for sudden cardiac arrest because their heart muscles are too weak to effectively pump blood throughout the body, a condition called cardiomyopathy.

But little evidence exists to help doctors decide when it's better to choose a single-chambered ICD for patients or the more complex dual-chambered model.

The study, published in the May 15 issue of the Journal of the American Medical Association, compared the fates of more than 32,000 Medicare patients who received ICDs, from 2006 through 2009. None of the patients also needed a pacemaker, a device that speeds up a slow heartbeat.

"There is evidence for greater risk of complications. Not clear evidence of benefit. That risk-benefit ratio really doesn't support the routine use of dual-chamber devices for primary prevention," said study co-author Dr. Pamela Peterson, an associate professor of medicine at the University of Colorado at Denver.

About one-third of patients received a single-chamber ICD, in which an electrical lead is attached to the heart's lower right pumping chamber. The other two-thirds got dual-chamber devices, in which wires are attached to the upper and lower chambers of the heart's right side.

After a year, patients who got single-chamber ICDs were no more likely to die or be hospitalized than patients who got the more expensive dual-chamber models. They were, however, slightly less likely to face serious complications, including fluid build-up around the heart or lungs and mechanical problems with the device that required a second surgery to fix.

That was true even after researchers adjusted their results to control for any differences between patients who got single- and dual-chamber devices.

Overall, close to 4 percent of patients with single-chamber ICDs had complications with their devices compared to about 5 percent of patients with dual-chamber models, the investigators found.

The study was observational, which means researchers couldn't prove that the type of ICD was the only reason patients fared the way they did. Though they tried to carefully control their data for important differences between the two groups, other factors they couldn't measure, such as medications people were taking, may have influenced the results.

The study was funded by a grant from the U.S. Agency for Healthcare Research and Quality.

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