Original-clinicalEliminating right ventricular pacing may not be best for patients requiring implantable cardioverter-defibrillators
Introduction
Multicenter controlled clinical trials have shown that excessive amounts of right ventricular (RV) pacing are associated with increased risk of atrial fibrillation, heart failure hospitalization, implantable cardioverter-defibrillator (ICD) therapy, ventricular arrhythmias including ventricular fibrillation, and increased risk of cardiovascular mortality in patients who receive pacemakers or ICDs.1, 2, 3, 4 Post hoc analyses from several studies1, 4, 5, 6, 7, 8, 9 have suggested that RV pacing has negative implications. However, these studies are inconclusive with regard to how much RV pacing is deleterious. It remains uncertain how far attempts should be made to prevent RV pacing in patients with ICDs. Several device manufacturers have developed algorithms that attempt to minimize RV pacing assuming that the optimal level of RV pacing is no RV pacing at all. However, no clinical evidence currently exists to support this.
The purpose of this analysis was to assess the relationship between various tiers of RV pacing and outcomes in the Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) study.10 We questioned whether the optimal amount of RV pacing in an ICD population is no RV pacing at all. In addition, we evaluated whether there was a range of RV pacing that appeared deleterious.
Section snippets
Methods
The INTRINSIC RV study was a multicenter, randomized, controlled, clinical trial assessing total mortality and heart failure (HF) hospitalization outcomes as the primary composite endpoint in 1530 patients who met the standard criteria for ICD implant.11 Atrioventricular (AV) Search Hysteresis was chosen as a treatment feature since it has been shown to reduce RV pacing by allowing intrinsic AV conduction beyond the programmed AV delay when proper programming characteristics are applied.12 The
Results
Baseline characteristics for all 715 patients programmed to a DDDR pacing mode, reported by RV pacing tier, are presented in Table 1. These patients are typical of ICD recipients in other clinical trials but differed significantly across the six pacing groups with respect to age, clinical history of ventricular tachycardia, atrial fibrillation, and atrial flutter, and amiodarone use. Event rates (total mortality and HF hospitalization) evaluated against cumulative RV pacing are presented in
Discussion
These data show that the amount of RV pacing is associated with HF hospitalization and total mortality in a large ICD population. Remarkably, patients who were RV pacing 0–9% were more likely to experience an unfavorable event (death or HF hospitalization) than the group that demonstrated the best outcome, that is, those patients with RV pacing 10%–19%. The reasons for this are not certain but may be due to patient characteristics, a balance in the adverse effects of RV pacing, or the
Limitations
The lack of baseline electrocardiographic and echocardiographic data, not routinely mandated in the INTRINSIC RV trial, makes it difficult to correlate any findings from these parameters with the burden of ventricular pacing, susceptibility to HF hospitalization, and death. Based on the current data, it is not possible to discern the absolute benefit of RV pacing in lieu of patient-specific, physiological AV interval optimization.
Patients in different RV pacing tiers tended to differ in other
Conclusion
High and very low levels of RV pacing in ICD patients enrolled in the INTRINSIC RV trial were associated with poorer outcomes. These data suggest that reducing RV pacing to very low levels (<10%) does not necessarily improve outcomes. Furthermore, patients pacing between 10% and 19% experienced fewer events. RV pacing delivered as it was in the INTRINSIC RV trial, that is, not excessively, does not appear harmful and may benefit ICD recipients.
Acknowledgments
The authors thank the patients who participated in the INTRINSIC RV trial and the participating investigators and institutions.
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Altered mitochondrial expression genes in patients receiving right ventricular apical pacing
2016, Experimental and Molecular PathologyCitation Excerpt :Right ventricular apical (RVA) pacing, a commonly selected pacing site, provides an adequate electrical impulse to the right ventricular myocardium, thus restoring a physiological excitation–conduction of the heart. It is well known that pacing-induced remodeling could be detrimental in the long term, causing electro-mechanical dyssynchrony, developing a pacemaker induced cardiomyopathy and congestive heart failure in some patients (Sweeney et al., 2003; Olshansky et al., 2007; Wilkoff et al., 2002). The incidence of heart failure is about 3.3% in patients with high-grade atrioventricular block during the 3 years after pacemaker implantation (Toff et al., 2005).
Risk of heart failure- and cardiac death gradually increases with more right ventricular pacing
2015, International Journal of CardiologyCitation Excerpt :However, when looking at rates of HF hospitalization for categories of increasing %RVP observed in MOST, a clear trend of more events in patients receiving more frequent RVP is noted, similarly to our results. Also, the INTRINSIC-RV study suggests a non-linear association between %RVP and the composite endpoint of all-cause mortality and HF hospitalization in DDD-ICD recipients [5]. Remarkably, a disproportionally high event rate was noted in patients receiving 0–9% RVP.
Chronic right ventricular apical pacing: Adverse effects and current therapeutic strategies to minimize them
2014, International Journal of CardiologyHRS/ACCF expert consensus statement on pacemaker device and mode selection
2012, Journal of the American College of Cardiology
This study was funded in full by Boston Scientific CRM (formerly Guidant Corporation).
- 1
Brian Olshansky has received support from and is a consultant for Boston Scientific CRM
- 2
Darin R. Lerew has an ownership interest in and is employed by Boston Scientific CRM
- 3
Scott Brown is an employee of the Integra Clinical Group and is employed as a consultant to Boston Scientific CRM
- 4
Kira Stolen has an ownership interest in and is employed by Boston Scientific CRM.