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Updated: Feb 10, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
12:45

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

Published on: December 11, 2017

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Sex-Specific Response to Cardiac Resynchronization Therapy: Effect of Left Ventricular Size and QRS Duration in

Niraj Varma1, Jason Lappe1, Jiayan He2

  • 1Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.

JACC. Clinical Electrophysiology
|May 16, 2018
PubMed

Insights

Cardiac resynchronization therapy (CRT) response varies by sex, with women showing a higher response rate. Adjusting for heart size, not body size, resolved sex differences in CRT effectiveness for patients with left bundle branch block.

Area of Science:

  • Cardiology
  • Medical Devices
  • Electrophysiology

Background:

  • Cardiac resynchronization therapy (CRT) effectiveness can differ between sexes.
  • Left bundle branch block (LBBB) is a key indicator for CRT, but response rates vary.
  • Understanding factors influencing CRT response is crucial for optimizing patient outcomes.

Purpose of the Study:

  • To assess how body size and heart size impact sex-specific CRT response rates.
  • To analyze the relationship between QRS duration (QRSd) and CRT response across sexes.
  • To determine if sex differences in CRT response are explained by body surface area (BSA) or heart size.

Main Methods:

  • Evaluated 130 patients with nonischemic cardiomyopathy and LBBB (NYHA class III/IV).
  • Measured left ventricular mass (LVM) and end-diastolic volume via echocardiography.
  • Defined positive CRT response by improvement in left ventricular ejection fraction (LVEF) post-therapy.

Main Results:

  • Overall CRT improved LVEF significantly (19% to 32%) in the study cohort.
  • Women exhibited a higher CRT response rate (90%) compared to men (66%).
  • Sex differences in response were linked to QRSd and heart size (LVM), not BSA.

Conclusions:

  • Sex-specific differences in CRT response among LBBB patients were observed.
  • These differences were not explained by strict LBBB criteria or BSA.
  • Normalizing QRSd for heart size (LVM or volume) resolved the observed sex disparities in CRT response.
Abstract

Keywords:
CRTLBBBLV massLV volumeQRS durationcardiac resynchronization therapyheart failuresex

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