Key result
Moderate-to-high RVP burden is linked to ~35% higher ICD shock risk, whereas high pacing reduces it.
Why the study?
A high burden of right ventricular pacing may have a proarrhythmic effect in patients with implantable cardioverter defibrillators, motivating an assessment of how increased pacing burden impacts shock incidence in a large real-world registry.
Does increased right ventricular pacing burden increase the incidence of shocks in patients with implantable cardioverter defibrillators?
Cohort (n=36,528)
Yes
Does increased right ventricular pacing burden increase the incidence of shocks in patients with implantable cardioverter defibrillators?
In ICD patients without CRT, intermediate right ventricular pacing burden (1–80%) is associated with a higher rate of ICD shocks compared to <1% pacing, whereas near-complete pacing dependence (≥95%) is associated with a lower shock risk, suggesting a proarrhythmic effect of mixed intrinsic and paced rhythms.
Background High burden of right ventricular pacing (RVP) may have a proarrhythmic effect in patients with implantable cardioverter defibrillators (ICDs). Purpose To assess how increased RVP burden impacts the incidence of shocks in ICD patients using a large real-world registry. Methods In a multicentre retrospective study utilizing a vendor-neutral remote monitoring (RM) platform, we included ICD patients with data on RVP burden and the date of shock delivery from January 2015 to November 2025. Patients with cardiac resynchronization therapy were excluded. The RVP burden (%RVP) for each patient was extracted from the initial transmission via a vendor-neutral remote monitoring platform. Regular RM logs recorded the date of each shock delivered. Results Among 36,528 patients with ICDs, the mean age was 63±13 years, and 30.2% were female. The total number of transmissions was 873,997, with a median of 15 per patient [7–29]. The median %RVP was estimated at 0.07% [0.00–1.00%], and the mean left ventricular ejection fraction was 40±15%. During a median follow-up of 3.9 [1.75–6.44] years, 4835 (13.2%) patients received shocks. Of these, 76.0% received anti-tachycardia pacing before the initial shock therapy. Multivariable Cox proportional hazards models were constructed, adjusting for age, sex, HF, and single- or dual-chamber device. Hazard ratios (HRs) for the initial shock occurrence in %RVP increase with %RVP up to 80% relative to %RVP < 1% (1-5%, HR 1.40 [1.30–1.52]; 5-10%, HR 1.32 [1.10–1.59]; 10-40%, HR 1.36 [1.18–1.58]; 40-80%, HR 1.35 [1.10–1.65]). By contrast, in ICD patients with very high RVP dependence (≥ 95%), the HR drops compared to those with %RVP < 1% (HR 0.71 [0.55–0.90]) (Figure). Conclusions Increased RVP burden was associated with a higher shock rate in patients with ICDs, whereas extremely high RVP dependence was not. These results suggest that a mixed intrinsic and paced ventricular rhythm may be associated with an increased risk of shock.
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Iwakawa et al. (2026) conducted a cohort in Patients with implantable cardioverter defibrillators (ICDs) (n=36,528). Right ventricular pacing (RVP) burden vs. RVP burden <1% was evaluated on Initial ICD shock occurrence (HR 1.35 (40-80% RVP) / HR 0.71 (≥95% RVP), 95% CI 1.10-1.65). Moderate-to-high right ventricular pacing burden (1-80%) increased ICD shock risk vs <1% pacing (40-80%: HR 1.35, 95% CI 1.10-1.65), whereas ≥95% pacing lowered risk (HR 0.71, 95% CI 0.55-0.90).
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