Lead one ratio in left bundle branch block predicts poor cardiac resynchronization therapy response

Abstract

Background A low electrocardiogram (ECG) lead one ratio (LOR) of the maximum positive/negative QRS amplitudes is associated with lower left ventricular ejection fraction (LVEF) and worse outcomes in left bundle branch block (LBBB); however, the impact of LOR on cardiac resynchronization therapy (CRT) outcomes is unknown. We compared clinical outcomes and echocardiographic changes after CRT implantation by LOR. Methods Consecutive CRT‐defibrillator recipients with LBBB implanted between 2006 and 2015 at Duke University Medical Center were included (N = 496). Time to heart transplant, left ventricular assist device (LVAD) implantation, or death was compared among patients with LOR P = .01) for heart transplant, LVAD, or death. Patients with LOR P = .04) and LV end systolic volume (ΔLVESV −9 ± 27 vs −22 ± 26%, P = .03) after CRT. In patients with QRS duration (QRSd) ≥150 ms, LOR P = .008) for heart transplant, LVAD, or death, compared with LOR ≥12. Conclusions Baseline ECG LOR <12 portends worse outcomes after CRT implantation in patients with LBBB, specifically among those with QRSd ≥150 ms. This ECG ratio may identify patients with a class I indication for CRT implantation at high risk for poor postimplantation outcomes.