Use of a cardiac resynchronization therapy device to provide overdrive atrial pacing does not prevent patients with heart failure from developing permanent atrial fibrillation, according to a late-breaking clinical trial presentation at the annual meeting of the American Heart Association.

MASCOT was a prospective, randomized, controlled trial of patients with heart failure enrolled from centers in Italy, France, Belgium, Germany and Greece. The study population was 79 percent male, with a mean age of 68 years. There were 197 patients in both the treatment and control arms. The treatment arm added atrial overdrive pacing to resynchronization, which uses ventricular pacing to improve heart function.

“This is the first prospective randomized study to analyze the effects of using a resynchronization device to prevent the development of atrial fibrillation in heart failure patients,” said Luigi Padeletti, MD, the study’s principal investigator and professor of cardiology and director of the Postgraduate School of Cardiology, University of Florence, Italy.

The one-year results of the two-year study demonstrated the device is safe, and the programmed algorithm is safe in patients with serious heart failure, New York Heart Class III or IV, and a left ventricular ejection fraction of 35 percent or less. However, the study did not find any statistically significant difference between the development of permanent AF in the treated and control groups (3.3 percent in both groups).

Researchers found a trend toward reduced mortality in the treated versus control group, with 7.6 percent mortality in the treated group compared with 11.7 percent mortality in the control group, but the difference was not statistically significant.