Abstract 2912: The Effect of Cumulative Right Ventricular Pacing on the Long-Term Benefit of the Implantable Cardioverter Defibrillator
Background: Active right ventricular (RV) pacing was shown to increase the risk for heart failure events in patients with an ICD. However, currently there are no data regarding the long-term effect of RV pacing on ICD efficacy.
Methods: Post-trial mortality data (through April 2009) were obtained for all patients enrolled in the Multicenter Automatic Defibrillator Trial-II (MADIT II). Data on ventricular pacing were available in 601 (83%) of ICD-treated patients in the trial. The number of ventricular paced beats over the total number of beats during the trial was categorized as low- (≤50%) and high- (>50%) cumulative RV pacing. Cox proportional hazards regression modeling was carried out to evaluate the long-term benefit of ICD vs. non-ICD therapy in the 2 pacing categories.
Results: At 7 years of follow-up from enrollment mortality rates were lowest among patients who received ICDs which were programmed to provide low RV pacing (30%), and similar in patients with ICDs programmed to provide high RV pacing (48%) and in non-ICD patients (55%; Figure⇓). Accordingly, in multivariate analysis ICD therapy was associated with a pronounced 52% (p<0.001) reduction in the risk of long-term mortality among patients in whom the devices provided low RV pacing, whereas the long-term benefit of the ICD was attenuated (19% risk reduction; p=0.001) in the high RV pacing subgroup.
Conclusions: Our findings demonstrate the detrimental long-term effects of RV pacing in ICD recipients. Primary prevention with ICDs that are programmed to provide a limited amount of RV pacing is associated with a pronounced reduction in the risk of long-term mortality.