Background: Pediatric patients paced for complete atrioventricular block (CAVB) are at risk of developing dilated cardiomyopathy (DCM). We sought to explore the role played by the setting of ventricular pacing.
Methods and results: A total of 35 patients <18 years of age at diagnosis were enrolled. Twenty-eight (80%) received pacemakers after a mean follow-up of 10 years, and most were paced from right ventricular (RV) apex (n = 23). None of the 7 patients without pacemakers developed DCM, whereas 8 (35%) paced from RV apex had DCM 2.6 +/- 2.2 years after pacing. The percentage of ventricular pacing was >90% in all patients. Multivariate analysis revealed that the cumulative Z score of lower ventricular rate setting was the single most important risk factor for DCM (HR, 3.14; 95% CI, 1.07-9.19; P = .037). Subgroup analysis in patients with VVI/VVIR modes revealed an even stronger predictive value of the cumulative Z score of lower ventricular rate setting (HR, 9.12; 95% CI, 1.53-54.24; P = .015).
Conclusions: Higher setting of the lower ventricular rate, though still within the age-appropriate range, was associated with increased risk of developing DCM in pediatric patients with CAVB and chronic RV apical pacing.