Horizontal QRS axis predicts response to cardiac resynchronization therapy in heart failure patients with left bundle branch block

Abstract

Background: Electrocardiogram criteria for left bundle branch block (LBBB) inadequately predict left ventricular electrical dyssynchrony, complicating cardiac resynchronization therapy (CRT) candidate selection. Objective: This study aimed to investigate the predictive value of the horizontal QRS axis for CRT response in heart failure (HF) patients with LBBB patterns. Methods: The direction and magnitude of the horizontal QRS axis were calculated using the net amplitudes in leads V2 and V6. CRT response was defined as a ≥10% increase in left ventricular ejection fraction and at least 1 New York Heart Association class reduction 1 year after CRT implantation. The composite end point included HF hospitalization or all-cause mortality. Results: Of 244 consecutive CRT recipients, 156 (63.9%) responded favorably; 88 (36.1%) were nonresponders. The horizontal QRS axis demonstrated significant backward deviation (−75.5° [−79.7° to −69.0°] vs −65.0° [−73.0° to −46.5°]; P < .001) and larger magnitude (35.5 ± 10.9 mm vs 25.5 ± 10.5 mm; P < .001) in CRT responders compared with nonresponders. The direction and magnitude independently predicted CRT response with an area under the curve of 0.778 (95% confidence interval [CI], 0.717–0.839) and 0.749 (95% CI, 0.685–0.814), respectively. Combining both parameters increased the area under the curve to 0.814 (95% CI, 0.760–0.868). Moreover, the direction and magnitude of the horizontal QRS axis, or their combination, predicted the composite end point of HF hospitalization or all-cause mortality, with hazard ratios of 0.36 (95% CI, 0.22–0.60), 0.41 (95% CI, 0.25–0.67), and 0.25 (95% CI, 0.15–0.41), respectively. Conclusion: Horizontal QRS axis accurately predicts CRT response and prognosis in HF patients with LBBB.

Document Type

Journal Article

Date of Publication

1-1-2025

Volume

22

Issue

7

PubMed ID

39536809

Publication Title

Heart Rhythm

Publisher

Elsevier

School

Centre for Precision Health / School of Medical and Health Sciences

RAS ID

76477

Funders

National Natural Science Foundation of China (82073659) / Provincial Medical Scientific Research Foundation of Guangdong (A2021084) / Provincial Science and Technology Special Fund of Guangdong (20211231071-4) / Funding for Guangdong Medical Leading Talent / First Affiliated Hospital, SUMC, China (2019\u20132022) / 2020 Li Ka Shing Foundation Cross-Disciplinary Research Grant (2020LKSFG19B) / Grant for Key Disciplinary Project of Clinical Medicine under the High-level University Development Program, Guangdong, China (2024)

Comments

Chen, Z., Chu, J., Wang, J., Cai, C., Lu, X., Song, M., Balmer, L., Wang, W., & Tan, X. (2025). Horizontal QRS axis predicts response to cardiac resynchronization therapy in heart failure patients with left bundle branch block. Heart Rhythm, 22(7), e122-e131. https://doi.org/10.1016/j.hrthm.2024.11.011

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e122

Last Page

e131

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Link to publisher version (DOI)

10.1016/j.hrthm.2024.11.011