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

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 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 (Delta LVEDV -4 +/- 21 vs -13 +/- 23%, P = .04) and LV end systolic volume (Delta LVESV -9 +/- 27 vs -22 +/- 26%, P = .03) after CRT. In patients with QRS duration (QRSd) >= 150 ms, 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. 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.