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Related Experiment Video

Updated: Feb 1, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
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Cardiac resynchronization therapy improves myocardial conduction.

Mei Yang1,2, Xuping Li2,3, Dachun Yang2

  • 1Department of Cardiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Pacing and Clinical Electrophysiology : PACE
|December 15, 2018
PubMed
Summary

Cardiac resynchronization therapy (CRT) improves ventricular conduction, with continuous QRS narrowing indicating a super-response. This electrical marker of CRT is linked to reduced mortality risk post-generator replacement.

Keywords:
QRS narrowingcardiac resynchronization therapygenerator replacementsuper-response

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Devices

Background:

  • Cardiac resynchronization therapy (CRT) is known to improve left ventricular remodeling and systolic function.
  • The impact of CRT on ventricular conduction, however, remains less understood.

Purpose of the Study:

  • To investigate the relationship between patient response to CRT and changes in QRS duration.
  • To determine if QRS narrowing serves as a marker for CRT efficacy.

Main Methods:

  • A cohort of 114 patients receiving CRT with defibrillator (CRT-D) underwent assessment at 6 months post-implantation and at generator replacement (GR).
  • Patients were categorized into super-responders (LVEF ≥ 50%), responders (LVEF 36-49% with >5% increase), and non-responders based on left ventricular ejection fraction (LVEF) changes.
  • QRS duration was measured at baseline, 6 months, and at GR to evaluate changes.

Main Results:

  • Significant QRS narrowing was observed at 6 months in both super-responders and responders.
  • Super-responders demonstrated further QRS narrowing between 6 months and GR.
  • QRS duration change post-6 months was independently associated with super-response, and a narrowing of ≥ 10 ms correlated with reduced all-cause mortality after GR.

Conclusions:

  • Continuous QRS narrowing after CRT functions as an electrical marker of a super-response.
  • Sustained QRS narrowing beyond 6 months post-CRT implantation is associated with a decreased risk of mortality.