April 15 (HealthDay News) -- The blood pressure drug valsartan may not prevent episodes of a dangerous abnormal heart rhythm called atrial fibrillation, an Italian study finds.
Earlier research had suggested that valsartan (Diovan) might reduce the occurrence of atrial fibrillation, a faulty heartbeat that can lead to the formation of clots that can cause heart attack or stroke.
"But in the patients we randomized in this study, it was not useful in preventing recurrence," said study author Dr. Aldo P. Maggioni, director of the ANMCO Research Center in Florence. His team published the findings in the April 16 issue of the New England Journal of Medicine.
The new study included 1,442 people who had two or more recent episodes of atrial fibrillation, in which the upper chambers of the heart flutter uselessly rather than pumping blood. Half were given valsartan, while the other half got a placebo.
Over a one-year follow-up, the incidence of atrial fibrillation episodes was about equal in both groups, occurring in 51.4 percent of those taking valsartan and 52.1 percent of those taking placebo.
That finding does not completely rule out using valsartan -- or other members of the angiotensin II-receptor blocker family to which that drug belongs -- for certain patients with atrial fibrillation, Maggioni said. "In primary prevention or after a few episodes, an angiotensin-receptor blocker could be useful," he added. "But for recurrent atrial fibrillation, it is probably too late."
And the study does not exclude the use of valsartan to prevent atrial fibrillation in people with heart failure, a separate cardiac ailment in which the heart loses ability to pump blood, said Dr. Anne M. Gillis, director of the arrhythmia program at the University of Calgary in Canada, who wrote an accompanying editorial.
"Only 8 percent of the people in the study had heart failure," Gillis noted. "In other studies, there has been a significant reduction of atrial fibrillation in patients with heart failure."
The Italian trial also included very few people with paroxysmal atrial fibrillation, in which abnormal heartbeat occurs only occasionally, she said, leaving open the possibility that valsartan might be of help to those patients.
The drug does have its uses in helping to control high blood pressure and "in patients who have heart failure, where it is an established therapy where ACE inhibitors are not indicated," Gillis said.
But as it now stands "there is no evidence that valsartan is effective as a secondary prevention strategy" for atrial fibrillation, she said.
SOURCES: Aldo P. Maggioni, M.D., director, ANMCO Research Center, Florence, Italy; Anne M. Gillis, professor, medicine, and director, arrhythmia program, University of Calgary, Alberta, Canada; April 16, 2009, New England Journal of Medicine