Increases in Repolarization Heterogeneity Predict Left Ventricular Systolic Dysfunction and Response to Cardiac Resynchronization Therapy in Patients with Left Bundle Branch Block.

INTRODUCTION: This study aimed to investigate the association between T-wave morphology and impaired left ventricular ejection fraction (LVEF) in patients with complete left bundle branch block (cLBBB), and the predictive value of T-wave morphology for response to cardiac resynchronization therapy (CRT). METHODS AND RESULTS: We enrolled 189 patients with cLBBB on electrocardiogram performed between January 2007 and December 2011 who underwent standard echocardiography. Repolarization parameters, including the QRS-to-T angle (TCRT), T-wave morphology dispersion (TMD), T-wave loop area (PL), and T-wave residuum (TWR), were reconstructed from digital standard 12-lead electrocardiograms by T-wave morphology analysis. CRT response was defined as >/=15% reduction in left ventricular end-systolic volume at 12 months after CRT implantation. The clinical outcome endpoint was a composite of heart failure hospitalization, heart transplantation, or death during follow up (mean, 5.8 years). On logistic regression, a higher heart rate, longer QRS duration, increased TMD, and larger TWR were all independently associated with LVEF <40%. Among 40 patients who underwent CRT, those with a larger TMD (p=0.007), larger PL (p=0.025), and more negative TCRT (p=0.015) had better response to CRT. A large TMD (p=0.018) and large PL (p=0.003) were also independent predictors of the clinical outcome endpoint. CONCLUSION: Increases in repolarization heterogeneity in patients with cLBBB are associated with impaired LVEF. A large TMD and large PL may be useful as additional predictors of response to CRT, improving patient selection for CRT. This article is protected by copyright. All rights reserved.