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Published at www.nejm.org November 15, 2009 (10.1056/NEJMoa0907555)

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ABSTRACT

Background Observational studies suggest that conventional right ventricular apical pacing may have a deleterious effect on left ventricular function. In this study, we examined whether biventricular pacing is superior to right ventricular apical pacing in preventing deterioration of left ventricular systolic function and cardiac remodeling in patients with bradycardia and a normal ejection fraction.

Methods In this prospective, double-blind, multicenter study, we randomly assigned 177 patients in whom a biventricular pacemaker had been successfully implanted to receive biventricular pacing (89 patients) or right ventricular apical pacing (88 patients). The primary end points were the left ventricular ejection fraction and left ventricular end-systolic volume at 12 months.

Results At 12 months, the mean left ventricular ejection fraction was significantly lower in the right-ventricular-pacing group than in the biventricular-pacing group (54.8±9.1% vs. 62.2±7.0%, P<0.001), with an absolute difference of 7.4 percentage points, whereas the left ventricular end-systolic volume was significantly higher in the right-ventricular-pacing group than in the biventricular-pacing group (35.7±16.3 ml vs. 27.6±10.4 ml, P<0.001), with a relative difference between the groups in the change from baseline of 25% (P<0.001). The deleterious effect of right ventricular apical pacing occurred in prespecified subgroups, including patients with and patients without preexisting left ventricular diastolic dysfunction. Eight patients in the right-ventricular-pacing group (9%) and one in the biventricular-pacing group (1%) had ejection fractions of less than 45% (P=0.02). There was one death in the right-ventricular-pacing group, and six patients in the right-ventricular-pacing group and five in the biventricular-pacing group were hospitalized for heart failure (P=0.74).

Conclusions In patients with normal systolic function, conventional right ventricular apical pacing resulted in adverse left ventricular remodeling and in a reduction in the left ventricular ejection fraction; these effects were prevented by biventricular pacing. (Centre for Clinical Trials number, CUHK_CCT00037.)

Source Information

From the Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong (C.-M.Y., J.Y.-S.C., Q.Z., G.W.-K.Y., F.F., J.W.-H.F.); the Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China (Q.Z.); the Department of Cardiology, National Heart Institute, Kuala Lumpur, Malaysia (R.O., A.H., K.H.L.); the Department of Medicine, Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong (H.C.-K.C.); and the Department of Medicine, North District Hospital, Hong Kong (J.W.-H.F.).

This article (10.1056/NEJMoa0907555) was published on November 15, 2009, at NEJM.org.

Address reprint requests to Dr. Yu at the Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital and Institute of Vascular Medicine and Li Ka Shing Institute of Health and Sciences, Chinese University of Hong Kong, Hong Kong, or at cmyu{at}cuhk.edu.hk.

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