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Updated: Mar 1, 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

11.1K

Stricter criteria for left bundle branch block diagnosis do not improve response to CRT

Emanuele Bertaglia1, Federico Migliore1, Anna Baritussio1

  • 1Department of Cardiac, Thoracic, and Vascular Sciences, University of Padova, Padova, Italy.

Pacing and Clinical Electrophysiology : PACE
|May 26, 2017
PubMed

Insights

A stricter definition for left bundle branch block (LBBB) did not improve cardiac resynchronization therapy (CRT) response. Echocardiographic response rates were similar between patients meeting traditional LBBB criteria and those meeting stricter criteria.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Diagnostics

Background:

  • Cardiac resynchronization therapy (CRT) is effective for heart failure with left bundle branch block (LBBB).
  • New, stricter electrocardiography (ECG) criteria for LBBB diagnosis have been proposed, differing from current American Heart Association (AHA) guidelines.
  • The study aimed to compare CRT response rates between patients with traditional LBBB and those meeting the stricter LBBB criteria.

Purpose of the Study:

  • To evaluate the echocardiographic response to CRT in patients diagnosed with LBBB using traditional AHA criteria versus a stricter set of ECG criteria.
  • To determine if the proposed stricter LBBB definition improves patient selection for CRT.

Main Methods:

  • A consecutive cohort of patients undergoing CRT was analyzed from the CRT MORE registry.
  • Exclusion criteria included no-LBBB morphology, atrial fibrillation, right bundle branch block, and right ventricular pacing.
  • Strict LBBB was defined by specific QRS duration, morphology in V1-V2, and mid-QRS notching/slurring criteria. Echocardiographic response was defined as a ≥15% decrease in left ventricular end-systolic volume (LVESV) at 12 months.

Main Results:

  • Out of 335 LBBB patients, 131 (39%) met the strict LBBB criteria. QRS duration was longer in the strict LBBB group (166 ± 20 ms vs. 152 ± 25 ms).
  • Overall, 61% of patients responded to CRT. Response rates were comparable between strict LBBB (65%) and traditional LBBB (59%) groups (P = 0.267).
  • Multivariate analysis identified atrial fibrillation history, larger LVESV, and mid-QRS notching as independent predictors of CRT response.

Conclusions:

  • The stricter definition of LBBB did not lead to a significantly higher rate of echocardiographic response to CRT compared to the current AHA definition.
  • Mid-QRS notching emerged as an independent predictor of CRT response, suggesting its potential clinical significance.
Abstract

Keywords:
cardiac resynchronization therapycongestive heart failureleft bundle branch block

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