Dyssynchrony and the risk of ventricular arrhythmias

JACC Cardiovasc Imaging. 2013 Apr;6(4):432-44. doi: 10.1016/j.jcmg.2012.12.008.

Abstract

Objectives: The aim of our study was to evaluate the relationship between left ventricular (LV) dyssynchrony and the risk of ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients enrolled in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy) trial.

Background: Intraventricular mechanical dyssynchrony might be an important factor in ventricular arrhythmogenesis by enhancing electrical heterogeneity in heart failure patients. The effects of dyssynchrony have not yet been evaluated in a large cohort of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with defibrillator (CRT-D) patients.

Methods: LV dyssynchrony was measured at baseline and at 12-months by speckle-tracking echocardiography, defined as the standard deviation of time to peak systolic strain in 12 LV myocardial segments. The endpoint was the first VT/VF/death or VT/VF. LV dyssynchrony was evaluated in 764 left bundle branch block (LBBB) patients and in 312 non-LBBB patients.

Results: Baseline LV dyssynchrony was not predictive of VT/VF/death or VT/VF in LBBB or non-LBBB patients in either treatment arm. In CRT-D patients with LBBB, improvement in LV dyssynchrony over a year was associated with significantly lower incidence of VT/VF/death (p < 0.001) and VT/VF (p < 0.001) compared to ICD patients and to CRT-D patients with unchanged or worsening dyssynchrony. Among LBBB patients, 15% decrease in LV dyssynchrony was associated with lower risk of VT/VF/death (hazard ratio: 0.49, 95% confidence interval: 0.24 to 0.99, p = 0.049) and VT/VF (hazard ratio: 0.30, 95% confidence interval: 0.12 to 0.77, p = 0.009) as compared to ICD patients. Patients without LBBB receiving CRT-D did not show reduction in VT/VF/death or in VT/VF in relation to improving dyssynchrony when evaluating cumulative event rates or risk of events.

Conclusions: Baseline LV dyssynchrony did not predict VT/VF/death or VT/VF in mild heart failure patients with or without LBBB. CRT-induced improvement of LV dyssynchrony was associated with significant reduction of ventricular arrhythmias in patients with LBBB.

Trial registration: ClinicalTrials.gov NCT00180271.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Bundle-Branch Block / etiology
  • Bundle-Branch Block / physiopathology
  • Canada
  • Cardiac Resynchronization Therapy
  • Cardiac Resynchronization Therapy Devices
  • Chi-Square Distribution
  • Defibrillators, Implantable
  • Electric Countershock / instrumentation
  • Europe
  • Female
  • Heart Failure / etiology*
  • Heart Failure / physiopathology
  • Heart Failure / therapy
  • Humans
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Proportional Hazards Models
  • Prospective Studies
  • Risk Assessment
  • Risk Factors
  • Tachycardia, Ventricular / etiology*
  • Tachycardia, Ventricular / mortality
  • Tachycardia, Ventricular / physiopathology
  • Tachycardia, Ventricular / prevention & control
  • Time Factors
  • Treatment Outcome
  • Ultrasonography
  • United States
  • Ventricular Dysfunction, Left / complications*
  • Ventricular Dysfunction, Left / diagnostic imaging
  • Ventricular Dysfunction, Left / mortality
  • Ventricular Dysfunction, Left / physiopathology
  • Ventricular Dysfunction, Left / therapy
  • Ventricular Fibrillation / etiology*
  • Ventricular Fibrillation / mortality
  • Ventricular Fibrillation / physiopathology
  • Ventricular Fibrillation / prevention & control
  • Ventricular Function, Left*

Associated data

  • ClinicalTrials.gov/NCT00180271