Adaptive CRT in patients with normal AV conduction and left bundle branch block: Does QRS duration matter? Hiro Yamasaki a, ⁎ ,1 , Daniel Lustgarten b,1 , Jeffrey Cerkvenik c,1 , David Birnie d,1 , Maurizio Gasparini e,1 , Kathy Lia-Fun Lee f,1 , Yukio Sekiguchi a,1 , Niraj Varma g,1 , Bernd Lemke h,1 , Randall C. Starling g,1 , Kazutaka Aonuma a,1 a Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan b The University of Vermont Medical Center, Burlington, Vermont, United States c Medtronic, plc, Mounds View, MN, United States d University of Ottawa Heart Institute, Ottawa, Ontario, Canada e Istituto Clinico Humanitas Mirasole, Rozzano, Italy f Queen Mary Hospital, The University of Hong Kong, Hong Kong g The Cleveland Clinic, Cleveland, OH, United States h Department of Cardiology, Hospital Lüdenscheid, Lüdenscheid, Germany abstract article info Article history: Received 1 November 2016 Received in revised form 6 April 2017 Accepted 10 April 2017 Available online xxxx Background: Adaptive cardiac resynchronization therapy (aCRT) is a dynamic optimization algorithm which paces only the left ventricle (LV) when atrio-ventricular (AV) conduction is normal, thus reducing right ventric- ular (RV) pacing. However, the impact of QRS duration on aCRT efficacy remains uncertain. We examined wheth- er QRS duration impacts aCRT effectiveness in patients with left bundle branch block (LBBB) and preserved AV conduction. Methods: Randomized patients in the Adaptive CRT trial, which enrolled NYHA III/IV patients, were used in this analysis. Patients were randomized to receive aCRT or echo-optimized bi-ventricular CRT (control arm). End- points for this analysis were clinical composite score (CCS) at 6 months post-implant and time to first heart fail- ure (HF) hospitalization or death. Results: Among the 199 patients with LBBB and normal AV intervals at baseline, 80 patients (40%) had a baseline moderately wide QRS of 120–150 ms. In this subgroup, a greater proportion of aCRT patients had an improved CCS (79% vs. 50%) at 6 months compared to the control group (p = 0.03). There was also a trend toward a lower risk of death or HF hospitalization (hazard ratio: 0.53; 95% CI: 0.24–1.15; p = 0.10) in the moderately wide QRS subgroup with aCRT compared to the control arm. In the wide QRS subgroup, the efficacy was compa- rable in both treatment arms. Conclusion: Adaptive CRT was associated with improved patient outcomes over echo-optimized bi-ventricular CRT in patients with preserved AV conduction, LBBB, and moderately wide QRS. The adaptive cardiac resynchronization therapy trial (ClinicalTrials.gov Identifier: NCT00980057) was sponsored by Medtronic plc, Mounds View, MN. © 2016 Elsevier Ireland Ltd. All rights reserved. Keywords: Adaptive CRT Clinical response QRS duration 1. Introduction Cardiac resynchronization therapy (CRT) is an established therapy for symptomatic heart failure (HF) patients with left ventricular systolic dysfunction and a wide QRS [1,2]. Prospective, randomized trials of CRT have demonstrated a reduction in mortality and hospitalization, improved functional capacity, quality of life, and reversal of adverse car- diac remodeling [1,3,4]. Despite those benefits, up to one third of pa- tients fail to respond to therapy [1]. A patient level meta-analysis of five conventional bi-ventricular CRT randomized trials showed QRS du- ration to be the only predictor of benefit. Moreover, patients with a QRS b 140 ms had a decreased benefit from CRT [5]. Providing clarity around subgroup benefit and exploring alternative therapeutic options for non- responders is necessary. Although CRT is normally achieved through pacing both ventricles (biventricular [BiV] pacing), left ventricular (LV) only pacing has been shown to be non-inferior and even superior to BiV pacing in some International Journal of Cardiology xxx (2016) xxx–xxx ⁎ Corresponding author at: 2-1-1 Amakubo, Tsukuba, Ibaraki 305-8576, Japan. E-mail address: hyamasaki@md.tsukuba.ac.jp (H. Yamasaki). 1 This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. IJCA-24880; No of Pages 5 http://dx.doi.org/10.1016/j.ijcard.2017.04.036 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved. Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard Please cite this article as: H. Yamasaki, et al., Adaptive CRT in patients with normal AV conduction and left bundle branch block: Does QRS duration matter?, Int J Cardiol (2016), http://dx.doi.org/10.1016/j.ijcard.2017.04.036