Some Heart Failure Patients May Not Benefit from Cardiac Resynchronization Therapy

Newswise — Cardiac resynchronization therapy (CRT) showed a lack of benefit for a segment of patients with heart failure. Results presented in a late breaking trial at the American Heart Association Scientific Sessions today show that heart failure patients with normal QRS duration, a surrogate measure of electrical conduction, may not experience any improvement in exercise tolerance after having pacemakers implanted. Results also appear today in the online version of the New England Journal of Medicine.

"Heart failure affects approximately five million Americans, with 550,000 cases newly diagnosed each year," said Dr. Sherif F. Nagueh, cardiologist at the Methodist DeBakey Heart Center in Houston and co-author of the abstract presented today and last author on the paper appearing in the NEJM. "Results from this research will help us better define treatment options for patients with heart failure."

CRT is a therapy that uses implanted cardiac pacemakers to stimulate the right and left side of the heart to improve the heart's ability to pump.

CRT has been previously shown to be beneficial to heart failure patients with long QRS, and the therapy is an approved treatment for these patients. However, the Resynchronization Therapy in Narrow QRS (RETHINQ) trial showed that heart failure patients who have narrow, or normal, QRS do not experience improvements in the study's primary endpoint of peak VO2 or in secondary endpoints including a quality of life score, a 6-minute walk test and left ventricular (LV) reverse remodeling.

About the RethinQ studyThe RethinQ study, sponsored by St. Jude Medical, followed 172 patients for six months to determine whether CRT can help heart failure patients with a narrow QRS complex (as measured by electrocardiogram) and left ventricular mechanical dyssynchrony (when the different walls of the heart's main pumping chamber, the left ventricle, do not contract synchronously). In the RethinQ study, narrow QRS was defined as 130 milliseconds or less (120 milliseconds or less is considered normal). Pacemakers combined with defibrillators were implanted in patients, who were then randomized to CRT ON vs. CRT OFF groups.

For more information about the Methodist DeBakey Heart Center, see http://www.debakeyheartcenter.com.