MONDAY, Nov. 16 (HealthDay News) -- In patients with bradycardia and normal ejection fraction, conventional right ventricular pacing is associated with reduced left ventricular ejection fraction and adverse left ventricular remodeling compared to biventricular pacing, according to a study published online Nov. 15 in The New England Journal of Medicine to coincide with the American Heart Association Scientific Sessions, held from Nov. 14 to 18 in Orlando, Fla.

Cheuk-Man Yu, M.D., of the Chinese University of Hong Kong, and colleagues randomly assigned 177 patients in whom a biventricular pacemaker had been implanted to receive either right ventricular apical pacing or biventricular pacing.

After 12 months, the researchers found that the biventricular-pacing group had a significantly higher mean left ventricular ejection fraction than the right-ventricular-pacing group (62.2 versus 54.8), and a significantly lower left ventricular end-systolic volume (27.6 versus 35.7 ml). They also found that the biventricular-pacing group was significantly less likely to have ejection fractions of less than 45 percent (1 versus 9 percent).

"There is no compelling evidence that biventricular pacing should be selected at the time of implantation in all patients who have normal ventricular function and high-grade atrioventricular block," states the author of an accompanying editorial. "An alternative approach is to follow the patients carefully by obtaining annual echocardiograms and to convert patients to biventricular pacing systems only if a clinically significant change in left ventricular function or functional capacity is observed. The study by Yu et al provides additional evidence that right ventricular pacing can be deleterious, but it should not change current guidelines."

This study was supported by Medtronic; several authors reported financial relationships with the company.

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