Cardiac Resynchronization Defibrillator Therapy for Nonspecific Intraventricular Conduction Delay Versus Right Bundle Branch Block

J Am Coll Cardiol. 2019 Jun 25;73(24):3082-3099. doi: 10.1016/j.jacc.2019.04.025.

Abstract

Background: The benefits of cardiac resynchronization therapy (CRT) in patients with non-left bundle branch block (LBBB) conduction abnormality have not been fully explored.

Objectives: This study sought to evaluate clinical outcomes among Medicare-aged patients with nonspecific intraventricular conduction delay (NICD) versus right bundle branch block (RBBB) in patients eligible for implantation with a CRT with defibrillator (CRT-D).

Methods: Using the National Cardiovascular Data Registry implantable cardioverter-defibrillator (ICD) registry data between 2010 and 2013, the authors compared outcomes in CRT-eligible patients implanted with CRT-D versus ICD-only therapy among patients with NICD and RBBB. Also, among all CRT-D-implanted patients, the authors compared outcomes in those with NICD versus RBBB. Survival curves and multivariable adjusted hazard ratios (HRs) were used to assess outcomes including hospitalization and death.

Results: In 11,505 non-LBBB CRT-eligible patients, after multivariable adjustment, among patients with RBBB, CRT-D was not associated with better outcomes, compared with ICD alone, regardless of QRS duration. Among patients with NICD and a QRS ≥150 ms, CRT-D was associated with decreased mortality at 3 years compared with ICD alone (HR: 0.602; 95% confidence interval [CI]: 0.416 to 0.871; p = 0.0071). Among 5,954 CRT-D-implanted patients, after multivariable adjustment NICD compared with RBBB was associated with lower mortality at 3 years in those with a QRS duration of ≥150 ms (HR: 0.757; 95% CI: 0.625 to 0.917; p = 0.0044).

Conclusions: Among non-LBBB CRT-D-eligible patients, CRT-D implantation was associated with better outcomes compared with ICD alone specifically in NICD patients with a QRS duration of ≥150 ms. Careful patient selection should be considered for CRT-D implantation in patients with non-LBBB conduction.

Keywords: CRT-D; LBBB; NCDR; NICD; National Cardiovascular Data Registry; RBBB; cardiac resynchronization therapy defibrillator; non-left bundle branch block; nonspecific interventricular conduction delay; right bundle branch block.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Bundle-Branch Block* / diagnosis
  • Bundle-Branch Block* / epidemiology
  • Bundle-Branch Block* / physiopathology
  • Bundle-Branch Block* / therapy
  • Cardiac Conduction System Disease* / diagnosis
  • Cardiac Conduction System Disease* / epidemiology
  • Cardiac Conduction System Disease* / physiopathology
  • Cardiac Conduction System Disease* / therapy
  • Cardiac Resynchronization Therapy* / adverse effects
  • Cardiac Resynchronization Therapy* / methods
  • Cardiac Resynchronization Therapy* / statistics & numerical data
  • Defibrillators, Implantable / statistics & numerical data*
  • Electric Countershock / instrumentation
  • Electric Countershock / methods
  • Electrocardiography / methods
  • Female
  • Heart Ventricles / physiopathology*
  • Humans
  • Male
  • Medicare / statistics & numerical data
  • Outcome and Process Assessment, Health Care
  • Patient Selection
  • Registries
  • United States / epidemiology