Costlier Heart Device May Not Be Worth It: Study
Dual-chamber implanted defibrillators had more complications than single-chamber models
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.
An expert who was not involved in the research praised the study, but said its findings come with an important caveat. The study wasn't able to measure so-called "inappropriate" shocks, instances when the devices misfire after sensing an irregular, but harmless, heartbeat.
Patients describe the powerful jolt as feeling like they're being kicked or hit with a baseball bat. Inappropriate shocks can be a major quality-of-life issue for patients who get them frequently.
Dr. Gregg Fonarow, director of the Cardiomyopathy Center at the University of California, Los Angeles, said the dual-chamber defibrillator may have an advantage in that regard.
"A dual-chamber ICD device, along with its extra atrial lead, is frequently chosen in the belief that it will better discriminate fast heart rates originating in the upper versus lower chambers of the heart and thereby reduce the risk of inappropriate shocks from the device," said Fonarow.
Peterson agreed that not being able to study inappropriate shocks to patients was a limitation of the study. However, she said, "data that has looked at that doesn't demonstrate that there's a benefit of dual-chamber devices in decreasing inappropriate shocks."
Another question they weren't able to address in the study was cost. Single-chamber devices are initially less expensive than dual-chamber models.
A study published in September 2005 in the Journal of the American College of Cardiology said it costs roughly $34,000 for a single-chamber device and about $38,000 for a dual-chamber model.
But that study also found that the cost savings of single-chamber devices can be wiped out if patients need to upgrade to the dual-chamber model because their condition gets worse, a situation that occurs in about 5 to 6 percent of patients in clinical trials.