CRT devices do little to reduce heart failure

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Cardiac resynchronization therapy (CRT) to coordinate cardiac contractions did not cease worsening of mild heart failure in asymptomatic and mildly symptomatic heart failure patients, according to a presentation last week at the 2008 American College of Cardiology (ACC) Scientific Sessions.

A biventricular pacemaker, or CRT, can pace both sides of the heart and resynchronize a heart that does not beat in synchrony—common in patients with heart failure. CRT has been shown to reduce the size of the heart, inducing reverse left ventricular (LV) remodeling in NYHA III-IV patients.

A total of 610 patients were randomized in 73 centers in the U.S., Canada and Europe.

The REVERSE study, (REsynchronization reVErses Remodeling in Systolic left vEntricular dysfunction study) was a year-long, multi-center, randomized and double-blind controlled trial to assess whether CRT plus optimal medical therapy (CRT ON) can manage the progression of heart failure compared to optimal medical therapy alone (CRT OFF). Medtronic, who manufactures CRT systems, funded the study.

During the presentation, the researchers also noted that the FDA has not yet reviewed the clinical data to determine whether or not CRT systems are safe and effective in this patient population.

The primary endpoint of the study was a heart failure clinical composite response, which was analyzed comparing percent change in CRT ON versus CRT OFF and comparing the distribution of patients who had improved.

Lead author Cecilia Linde, MD, PhD, of the Karolinska University Hospital in Stockholm Sweden, reported that she and her colleagues found that the condition of heart failure patients were unchanged or even worsened on the therapies.

Despite failing to meet its primary endpoint, Medtronic and its researchers remain positive about the future of CRT devices: “I do think that REVERSE will move the field forward and likely get CRT to more patients," William Abraham, an investigator in the trial, and director of cardiovascular medicine at the Ohio State University Medical Center, told the Wall Street Journal.

The study did find that CRT devices improve to enlarged hearts in some patients, meeting its secondary endpoint. For the secondary endpoint, the left ventricle end-systolic volume index was evaluated after 12 months. Eligible patients had NYHA Class II heart failure or I with previous symptoms, QRS-duration ≥ 120 ms and LV ejection fraction ≤ 40 percent, according to the investigators.

Patients had to be on optimal drug therapy on a stable dose for at least one month and on beta-blockers for three months; and heart failure medications were not changed over the course of the REVERSE study unless by clinical necessity.

“REVERSE demonstrates that CRT, in combination with optimal medical therapy reverses left ventricular remodeling in asymptomatic and mildly symptomatic heart failure patients,” said Linde. “Extended study will further determine the significance of the study’s finding and what long-term benefits may exist with this combination therapy.”