Time-dependent risk reduction of ventricular tachyarrhythmias in cardiac resynchronization therapy patients: a MADIT-RIT sub-study.
OBJECTIVE
Data on the time-dependent benefit of cardiac resynchronization therapy with defibrillator (CRT-D) compared with a dual-chamber implantable cardioverter-defibrillator (ICD) to reduce death or ventricular tachycardia (VT) or ventricular fibrillation (VF) are limited. We aimed to evaluate the time-related risk of death or sustained VT or VF in patients receiving CRT-D vs. ICD in the MADIT-RIT trial.


RESULTS
Kaplan-Meier survival analyses and multivariate Cox regression models were utilized to compare the incidence and the risk of death or sustained VT/VF in the CRT-D and ICD subgroups by the elapsed time after device implantation (6 months). Of the ICD (n = 742) and CRT-D (n = 757) patients enrolled, the risk of death was lower in CRT-D vs. in ICD early after device implantation [hazard ratio (HR) = 0.42, 95% confidence interval (CI): 0.17-1.03, P = 0.058] and beyond 6 months of follow-up (HR = 0.39, 95% CI: 0.21-0.73, P = 0.004), with the 6-month interaction P = 0.899. The overall risk of sustained VT/VF was reduced in CRT-D vs. ICD patients (HR = 0.73, 95% CI: 0.52-1.03, P = 0.07). However, the risk was similar in the first 6 months (HR = 1.00, 95% CI: 0.62-1.62, P = 0.988), and a lower risk emerged 6 months after CRT-D implantation (HR = 0.58, 95% CI: 0.38-0.88, P = 0.011), with the 6-month interaction P = 0.059.


CONCLUSIONS
The reduced mortality risk of CRT-D compared with an ICD alone began early after device implantation and was sustained during long-term follow-up; the reduced risk for ventricular tachyarrhythmias did not emerge until 6 months after device implantation.


BACKGROUND
http://clinicaltrials.gov/ct2/show/NCT00947310.
Experimental and Clinical Research Center, a Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany Havelland Kliniken, Nauen, Germany.
Martin
M
Stockburger
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Arthur J
AJ
Moss
Department of Medicine, University of Iowa Health Care, Iowa City, IA, USA.
Brian
B
Olshansky
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Helmut
H
Klein
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Scott
S
McNitt
Department of Electrophysiology, The Henry Ford Hospital, Detroit, MI, USA.
Claudio
C
Schuger
Electrophysiology Department, Duke Medical Center, Durham, NC, USA.
James P
JP
Daubert
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Ilan
I
Goldenberg
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Anne-Christine H
AC
Ruwald
Semmelweis University, Heart Center, Budapest, Hungary.
Bela
B
Merkely
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA.
Wojciech
W
Zareba
University of Rochester Medical Center, 265 Crittenden Blvd., Box 653, Rochester, NY 14642, USA valentina.kutyifa@heart.rochester.edu.
Valentina
V
Kutyifa
D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000401:mortality* / Q000706:statistics & numerical data; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016019:Survival Analysis; D017180:Tachycardia, Ventricular / Q000401:mortality* / Q000517:prevention & control*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000401:mortality* / Q000517:prevention & control*
Cardiac resynchronization therapy; Implantable cardioverter-defibrillator; MADIT-RIT; Ventricular fibrillation; Ventricular tachycardia