Heart failure patients treated with a device that synchronizes pumping in the heart's ventricles showed no improvement in exercise capacity, researchers report.
The results were presented Tuesday at a late-breaking clinical trial session at the American Heart Association's annual meeting, in Orlando, Fla., and were expected to be published in the Dec. 13 print issue of the New England Journal of Medicine.
Cardiac Resynchronization Therapy (CRT) devices are surgically implanted and deliver electrical impulses to both ventricles at the same time, making both chambers contract simultaneously and thereby improving pumping efficiency.
While current guidelines support using CRT in patients with moderate to severe heart failure, this study aimed to see if the device could benefit patients outside those recommended parameters.
For this trial, 172 heart failure patients were randomly assigned to receive treatment with CRT or not.
Those treated with CRT showed no significant improvement in exercise capacity as measured by peak oxygen consumption. Some symptoms did improve, but quality-of-life scores and results of the six-minute hall walk test did not change significantly, the researchers reported.
"There was no significant difference in the change in peak oxygen consumption between the treatment group and the control group during cardiopulmonary testing," Dr. John Beshai, study lead author and director of pacemaker and defibrillator services in the division of cardiology at the University of Chicago, said at a news conference Tuesday. "Further research is necessary," he said.
The trial was funded by St. Jude Medical, which makes the CRT device.
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