Long-term implications of cumulative right ventricular pacing among patients with an implantable cardioverter-defibrillator.
BACKGROUND
Limited data regarding the effect of right ventricular pacing (RVP) on long-term survival following implantable cardioverter-defibrillator (ICD) implantation are available.


OBJECTIVE
The purpose of this study was to evaluate the effect of RVP on the long-term survival benefit of primary ICD therapy.


METHODS
Mortality data were obtained for all patients enrolled in the Multicenter Automatic Defibrillator Trial-II (MADIT-II) during an extended follow-up period of 8 years. The cumulative percent RVP during the trial was categorized as low (≤ 50% [n = 369]) and high (>50% [n = 198]). The benefit of ICD versus non-ICD therapy (n = 490) was evaluated in the two pacing categories during the early (0-3 years) and late (4-8 years) phases of the extended follow-up period.


RESULTS
During the early phase of the extended follow-up period, ICD therapy was associated with similar benefits in the low-RVP and high-RVP subgroups (hazard ratio [HR] = 0.35 and 0.38, respectively, P <.001 for both). In contrast, during the late phase, the long-term survival benefit of the ICD was maintained among patients with low RVP (HR = 0.60, P <.001) and attenuated among those with the high RVP (HR = 0.89, P = .45). An increased risk for late mortality associated with high versus low RVP was evident only among patients without left bundle branch [LBBB] at enrollment (HR = 1.63, P = .002).


CONCLUSIONS
Among ICD recipients, high RVP is associated with a significant increase in the risk of long-term mortality and with attenuated device efficacy. The deleterious effects of RVP are pronounced mainly in non-LBBB patients, suggesting a possible role for combined cardiac resynchronization-defibrillator therapy in this population.
Cardiology Division, University of Rochester Medical Center, Rochester, New York 14642, USA. alon.barsheshet@heart.rochester.edu
Alon
A
Barsheshet
Arthur J
AJ
Moss
Scott
S
McNitt
Christian
C
Jons
Michael
M
Glikson
Helmut U
HU
Klein
David T
DT
Huang
Jonathan S
JS
Steinberg
Mary W
MW
Brown
Wojciech
W
Zareba
Ilan
I
Goldenberg
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects / Q000379:methods / Q000401:mortality*; D002423:Cause of Death; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D016019:Survival Analysis; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis / Q000401:mortality / Q000628:therapy