Different response to vitamin D supplementation in children with RVOT morphology PVCs vs LV fascicular PVCs

Outflow tract premature ventricular contractions (PVCs) are typically benign arrhythmias in structurally normal hearts. Vitamin D insufficiency has been shown to cause PVCs in both children and adults. This study examined the impact of vitamin D supplementation in children with an increased burden of PVCs in 2 patient categories with distinct electrocardiogram morphologies: right ventricular outflow tract (RVOT) and left fascicular. We enrolled 46 patients (mean age 10.6 ± 4.1 years, 26% female) showing an increased burden of monomorphic PVCs (mean = 18,925/24 hours) and vitamin D deficiency. We compared 36 patients with RVOT morphology and 10 patients with left ventricular fascicular morphology. In the RVOT morphology group, the mean age was 12.7 ± 2.7 years, comprising 75% males and 25 females, with a PVC burden of 18,343.7 ± 13,836.2/24 hours and a 25-OH vitamin D level of 23.5 ± 9.4 ng/mL. After 2 months of oral vitamin D supplementation, the vitamin D level increased to 41.6 ± 6.3, followed by a considerable reduction in PVC burden to 3628.0 ± 2347.2. This group of children showed 80% reduction in PVC burden. In the left ventricular fascicular morphology group, the mean age was 6.9 ± 5.5 years, comprising 71% males and 29% females, with a PVC burden of 20,535.3 ± 20,867.9, and a vitamin D level of 25.8 ± 7.1 ng/mL. Following 3 months of oral vitamin D supplementation, vitamin D levels increased to 65.8 ± 42.8 ng/mL; however, there was no significant change in PVC burden (19,207.1 ± 22,807.8). Vitamin D supplementation may be effective in reducing PVC burden in children with vitamin D deficiency and RVOT PVCs.