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

Children with RVOT morphology PVCs showed an 80% reduction in PVC burden after 2 months of vitamin D supplementation.

• The RVOT group comprised 36 patients with a mean age of 12.7 ± 2.7 years, 75% males.
• Baseline PVC burden was 18,343.7 ± 13,836.2/24 hours, which reduced to 3628.0 ± 2347.2/24 hours after supplementation.
• Baseline 25-OH vitamin D level was 23.5 ± 9.4 ng/mL, which increased to 41.6 ± 6.3 ng/mL after 2 months of oral vitamin D supplementation.
• The reduction in PVC burden represented approximately 80% decrease from baseline.

Children with left ventricular fascicular morphology PVCs showed no significant change in PVC burden despite vitamin D supplementation.

• The left ventricular fascicular group comprised 10 patients with a mean age of 6.9 ± 5.5 years, 71% males.
• Baseline PVC burden was 20,535.3 ± 20,867.9/24 hours, which remained largely unchanged at 19,207.1 ± 22,807.8/24 hours after supplementation.
• Baseline 25-OH vitamin D level was 25.8 ± 7.1 ng/mL, which increased to 65.8 ± 42.8 ng/mL after 3 months of oral vitamin D supplementation.
• Despite a substantial increase in vitamin D levels, there was 'no significant change in PVC burden.'

The overall study population consisted of 46 pediatric patients with an increased burden of monomorphic PVCs and vitamin D deficiency.

• Mean age was 10.6 ± 4.1 years, with 26% female patients.
• Mean PVC burden at baseline was 18,925/24 hours across all patients.
• 36 patients had RVOT morphology PVCs and 10 patients had left ventricular fascicular morphology PVCs.
• All patients had vitamin D deficiency at enrollment.

The two PVC morphology groups differed notably in age, with RVOT patients being older than left fascicular patients.

• RVOT group mean age was 12.7 ± 2.7 years compared to 6.9 ± 5.5 years in the left fascicular group.
• Both groups had a male predominance (75% in RVOT group, 71% in left fascicular group).
• Baseline vitamin D levels were similar between groups (23.5 ± 9.4 ng/mL in RVOT vs 25.8 ± 7.1 ng/mL in left fascicular).
• Baseline PVC burdens were also comparable (18,343.7 ± 13,836.2 vs 20,535.3 ± 20,867.9/24 hours).

Vitamin D insufficiency has been established as a cause of PVCs in both children and adults.

• The study was motivated by prior evidence that vitamin D insufficiency causes PVCs in both pediatric and adult populations.
• Outflow tract PVCs are described as 'typically benign arrhythmias in structurally normal hearts.'
• The study enrolled only patients with vitamin D deficiency and increased PVC burden, suggesting a clinical hypothesis linking the two conditions.