title: The association between biventricular pacing and cardiac resynchronization therapy-defibrillator efficacy when compared with implantable cardioverter defibrillator on outcomes and reverse remodelling.
abstract: OBJECTIVE
  Previous studies on biventricular (BIV) pacing and cardiac resynchronization therapy-defibrillator (CRT-D) efficacy have used arbitrarily chosen BIV pacing percentages, and no study has employed implantable cardioverter defibrillator (ICD) patients as a control group.
  
  
  RESULTS
  Using Kaplan-Meier plots, we estimated the threshold of BIV pacing percentage needed for CRT-D to be superior to ICD on the end-point of heart failure (HF) or death in 1219 left bundle branch block (LBBB) patients in the MADIT-CRT trial. Patients were censored at the time of crossover. In multivariable Cox analyses, no difference was seen in the risk of HF/death between ICD and CRT-D patients with BIV pacing ≤90% [HR = 0.78 (0.47-1.30), P = 0.344], and with increasing BIV pacing the risk of HF/death was decreased [CRT-D BIV 91-96% vs. ICD: HR = 0.63 (0.42-0.94), P = 0.024 and CRT-D BIV ≥97% vs. ICD: HR = 0.32 (0.23-0.44), P < 0.001]. The risk of death alone was reduced by 52% in CRT-D patients with BIV ≥97% (HR = 0.48, P < 0.016), when compared with ICD patients. Within the CRT-D group, for every 1 percentage point increase in BIV pacing, the risk of HF/death and death alone significantly decreased by 6 and 10%, respectively. Increasing BIV pacing percentage was associated with significant reductions in left ventricular volume.
  
  
  CONCLUSIONS
  In patients with LBBB, who were in sinus rhythm at enrolment, BIV pacing exceeding 90% was associated with a benefit of CRT-D in HF/death when compared with ICD patients. Furthermore, BIV pacing ≥97% was associated with an even further reduction in HF/death, a significant 52% reduction in death alone, and increased reverse remodelling. Clinical trials.gov identifier: NCT00180271.
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark annechristinehuth@hotmail.com.
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Ruwald
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Ruwald
authors.affiliation: Cardiovascular Division, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Solomon
authors.affiliation: Cardiology Division, Duke University Medical Center, Durham, NC, USA.
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.affiliation: Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
authors.affiliation: Greenville University Health System, Greenville, SC, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Brenyo
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, CA, USA.
authors.forename: Duc
authors.initials: D
authors.lastname: Do
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, CA, USA.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanabe
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, CA, USA.
authors.forename: Amin
authors.initials: A
authors.lastname: Al-Ahmad
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Wang
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA.
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.affiliation: Heart Research Follow-up Program, University of Rochester Medical Center, 265 Crittenden Blvd. CU 420653, Rochester, NY 14642, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000401:mortality / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods* / Q000401:mortality; D017147:Defibrillators, Implantable; D005260:Female; D006333:Heart Failure / Q000628:therapy*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology
keywords: Biventricular pacing; Cardiac resynchronization therapy; Efficacy; Heart failure and death; Implantable cardioverter defibrillator; Left bundle branch block