Biventricular pacing is superior to conventional right ventricular pacing in patients who have atrioventricular block and left ventricular systolic dysfunction with mild to moderate heart failure, according to a study that was presented at the American Heart Association meeting last November and has now been published online April 24 in the New England Journal of Medicine.
In the industry-sponsored prospective randomized clinical trial, 691 patients at 58 medical centers in the United States and Canada were randomly assigned to receive right ventricular or biventricular pacing using a pacemaker or implantable cardioverter defibrillator (ICD), during an 8-year period, said Dr. Anne B. Curtis, professor and chair of the department of medicine at the University of Buffalo (N.Y.), and her associates.
After a mean follow-up of 37 months, the primary outcome – a composite of death from any cause, an urgent care visit for HF, or an increase of 15% or more in LV end-systolic volume index – occurred in 53.3% of the biventricular group, which was significantly lower than the 64.3% rate in the right ventricular group. This benefit was seen both in patients given a pacemaker and in those given an ICD, with the two devices exerting "a remarkably similar clinical effect" even though there was a marked difference in mean ejection fraction between pacemaker recipients and ICD recipients. This suggests that the benefit of biventricular pacing is not likely to be strongly related to EF, the investigators said (N. Engl. J. Med. 2013 April 24 [doi:10.1056/NEJMoa1210356]).
At the AHA meeting, study discussant Dr. Gerasimos S. Filippatos of the University of Athens said that the BLOCK-HF results would certainly lead to a reconsideration of current European Society of Cardiology and joint American College of Cardiology/AHA/Heart Rhythm Society guidelines for heart failure patients with heart block.
The authors noted that BLOCK-HF adds to the body of evidence suggesting that biventricular pacing in patients with AV block preserves systolic function." Dr. Curtis said while presenting the results in November that one of the key points of BLOCK-HF "was to look at whether or not putting patients through the added difficulty of implanting a biventricular pacing device has clear benefits – and the answer is yes."
This study was funded by Medtronic, which also provided the data collection and analysis. Dr. Curtis and her associates reported numerous ties to industry sources.