Effectiveness of cardiac resynchronization therapy by QRS morphology in the multicenter automatic defibrillator implantation trial-cardiac resynchronization therapy (MADIT-CRT)

  • Zareba W
  • Klein H
  • Cygankiewicz I
 et al. 
  • 166

    Readers

    Mendeley users who have this article in their library.
  • 425

    Citations

    Citations of this article.

Abstract

BACKGROUND This study aimed to determine whether QRS morphology identifies patients who benefit from cardiac resynchronization therapy with a defibrillator (CRT-D) and whether it influences the risk of primary and secondary end points in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial. METHODS AND RESULTS Baseline 12-lead ECGs were evaluated with regard to QRS morphology. Heart failure event or death was the primary end point of the trial. Death, heart failure event, ventricular tachycardia, and ventricular fibrillation were secondary end points. Among 1817 patients with available sinus rhythm ECGs at baseline, there were 1281 (70%) with left bundle-branch block (LBBB), 228 (13%) with right bundle-branch block, and 308 (17%) with nonspecific intraventricular conduction disturbances. The latter 2 groups were defined as non-LBBB groups. Hazard ratios for the primary end point for comparisons of CRT-D patients versus patients who only received an implantable cardioverter defibrillator (ICD) were significantly (P < 0.001) lower in LBBB patients (0.47; P < 0.001) than in non-LBBB patients (1.24; P = 0.257). The risk of ventricular tachycardia, ventricular fibrillation, or death was decreased significantly in CRT-D patients with LBBB but not in non-LBBB patients. Echocardiographic parameters showed significantly (P < 0.001) greater reduction in left ventricular volumes and increase in ejection fraction with CRT-D in LBBB than in non-LBBB patients. CONCLUSIONS Heart failure patients with New York Heart Association class I or II and ejection fraction ≤ 30% and LBBB derive substantial clinical benefit from CRT-D: a reduction in heart failure progression and a reduction in the risk of ventricular tachyarrhythmias. No clinical benefit was observed in patients with a non-LBBB QRS pattern (right bundle-branch block or intraventricular conduction disturbances). CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.

Author-supplied keywords

  • bundle-branch block
  • cardiac resynchronization therapy
  • heart failure
  • implantable cardioverter-defibrillators
  • prognosis

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • Wojciech Zareba

  • Helmut Klein

  • Iwona Cygankiewicz

  • W. Jackson Hall

  • Scott McNitt

  • Mary Brown

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free