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

Abstract

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. 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<12vs ≥12 using Cox-proportional hazard models. Changes in LVEF and LV volumes after CRT were compared by LOR. Baseline ECG LOR<12 was associated with an adjusted hazard ratio (HR) of 1.69 (95% CI: 1.12-2.40, P=.01) for heart transplant, LVAD, or death. Patients with LOR<12 had less reduction of LV end diastolic volume (ΔLVEDV -4 ± 21vs -13 ± 23%, P=.04) and LV end systolic volume (ΔLVESV -9 ± 27vs -22 ± 26%, P=.03) after CRT. In patients with QRS duration (QRSd) ≥150ms, LOR<12 was associated with an adjusted HR of 2.01 (95% CI 1.21-3.35, P=.008) for heart transplant, LVAD, or death, compared with LOR ≥12. Baseline ECG LOR<12 portends worse outcomes after CRT implantation in patients with LBBB, specifically among those with QRSd ≥150ms. This ECG ratio may identify patients with a class I indication for CRT implantation at high risk for poor postimplantation outcomes.