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Updated: Jan 26, 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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Left axis deviation in patients with left bundle branch block is a marker of myocardial disease associated with poor

Hanne Stavø Storkås1, Thomas Fritz Hansen1, Jasmine Borg Tahri1

  • 1Department of Cardiology, Gentofte University Hospital, Denmark.

Journal of Electrocardiology
|April 21, 2019
PubMed

Insights

Patients with left bundle branch block and left axis deviation have poorer outcomes with cardiac resynchronization therapy. This is due to increased scar tissue and hypertrophy, and less electrical delay, indicating LAD is a predictor of poor CRT response.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Cardiac Imaging

Background:

  • Cardiac resynchronization therapy (CRT) is a treatment for heart failure.
  • Patients with left bundle branch block (LBBB) often benefit from CRT.
  • Left axis deviation (LAD) in LBBB patients is associated with reduced CRT efficacy.

Purpose of the Study:

  • To investigate the underlying reasons for reduced CRT benefit in LBBB patients with LAD.
  • To identify predictors of CRT response in patients with LBBB and varying QRS axes.

Main Methods:

  • Sixty-eight CRT-eligible patients were categorized by QRS axis (normal, LAD, RAD).
  • Cardiac magnetic resonance (CMR) imaging assessed scar tissue; echocardiography evaluated ventricular remodeling before and after CRT.
  • Interlead electrical delays were measured to assess the electrical substrate.

Main Results:

  • Left axis deviation (LAD) was independently associated with poor left ventricular (LV) remodeling response to CRT (OR 0.21).
  • Patients with axis deviation exhibited more myocardial scar tissue and severe LV hypertrophy compared to normal axis patients.
  • Non-responders to CRT had a significantly higher scar tissue burden.

Conclusions:

  • Left axis deviation (LAD) in the context of left bundle branch block (LBBB) predicts a poor outcome following cardiac resynchronization therapy (CRT).
  • LAD in LBBB patients is linked to increased myocardial scar, LV hypertrophy, and reduced electrical activation delay.
  • These factors collectively contribute to the diminished response to CRT in this patient subgroup.
Abstract

Keywords:
Cardiac resynchronization therapyHeart failureLeft bundle branch blockQRS axis deviation

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