Reply to the Editor— Bipolar left ventricular pacing is associated with significant reduction in heart failure or death in CRT-D patients with LBBB

Reply to the Editor— Bipolar left ventricular pacing is associated with significant reduction in heart failure or death in CRT-D patients with LBBB We appreciate the comments on our study1 by Dr Mower. We generally agree that secondary analyses of clinical studies might be subject to an alpha error; however, our findings have since then been confirmed in another analysis using data of 65,620 patients with heart failure followed on the LATITUDE system (Boston Scientific).2 While we agree that our study did not provide detailed analyses of all possible polarities for cardiac resynchronization therapy, in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy, data on anodal stimulation or changes in pulse amplitudes were not recorded. However, data on the beneficial effects of anodal stimulation are ambiguous,3 and pacing parameters are infrequently reprogrammed during follow-up.4 Indeed, using biphasic pacing could potentially improve contractility and outcomes as indicated by pilot animal studies by Mower and colleagues.5,6 Until such benefits are prospectively proven in clinical studies, we suggest programming true bipolar left ventricular pacing polarity to potentially improve outcomes as indicated by our studies.1,2

1547-5271/$-see front matter B 2016 Heart Rhythm Society. All rights reserved.

Valentina Kutyifa, MD, PhD, FHRS [email protected] Heart Research Follow-up Program University of Rochester Medical Center Rochester, New York

References 1. Jame S, Kutyifa V, Aktas MK, et al. Bipolar left ventricular pacing is associated with significant reduction in heart failure or death in CRT-D patients with LBBB. Heart Rhythm 2016;13:1468–1474. 2. Kutyifa V, Moss AJ, Stein K, Wang PJ, Musat D, Jones P, Wehrenberg S. True bipolar left ventricular pacing is associated with better survival in cardiac resynchronization therapy patients. Circulation 2015;132:A15501. 3. Abu Sham’a R, Kuperstein R, Barsheshet A, et al. The effects of anodal stimulation on electrocardiogram, left ventricular dyssynchrony, and acute haemodynamics in patients with biventricular pacemakers. Europace 2011;13: 997–1003. 4. Klein N, Klein M, Weglage H, et al. Clinical efficacy of left ventricular pacing vector programmability in cardiac resynchronization therapy defibrillator patients for management of phrenic nerve stimulation and/or elevated left ventricular pacing thresholds: insights from the Efface Phrenic Stim study. Europace 2012;14: 826–832. 5. Mower MM, Hepp D, Hall R. Comparison of chronic biphasic pacing versus cathodal pacing of the right ventricle on left ventricular function in sheep after myocardial infarction. Ann Noninvasive Electrocardiol 2011;16:111–116. 6. Mower MM, Hall R, Cannom DS, Moss AJ. Biphasic versus monophasic cathodal ventricular pacing. J Cardiovasc Electrophysiol 2013;24:844–845.

http://dx.doi.org/10.1016/j.hrthm.2016.08.015