Introduction: Vitamin D deficiency has been associated with adverse vascular function including central aortic pressure (CAP), augmentation index (AI) and pulse wave velocity (PWV) in observational studies.
Hypothesis: We hypothesized that vitamin D supplementation in African Americans with poorly controlled HTN and hypertensive heart disease would modify these measures of vascular function.
Methods: Participants were recruited from a single center, urban emergency department. Those with vitamin D deficiency (< 20 ng/ml) underwent magnetic resonance imaging to measure left ventricular mass index (LVMI). Participants with increased LVMI were randomized to receive evidence based antihypertensive therapy (goal BP < 130/80 mmHg) along with adjunct vitamin D (50,000 IU every other week) or matching placebo for 1 year. Applanation tonometry was repeated at 16 and 52 weeks to measure CAP, PWV and AI.
Results: A total of 354 participants were screened, 113 (32%) of whom were randomized. Fifty-five participants were assigned to the vitamin D group and 58 participants to placebo. Average age was 46 years and 54% were female. Mean baseline BP was 161/102 mmHg and baseline vitamin D 11.0 ± 3.8 ng/ml. At week 52, mean vitamin D in the vitamin D group increased by 15 ± 2 ng/ml vs. 2 ± 1 ng/ml (p<0.01) in the placebo group. At week 16, mean BP was 133/88 mmHg in vitamin D and 138/91 in placebo, and at 52-weeks it was 136/90 mmHg and 134/90, respectively. At 16-week and 52-week follow-up (Figure), CAP and AI were reduced in both groups and PWV had minimal change. There was no statistically significant difference in these changes between the treatment and control groups.
Conclusions: Overall improvements in peripheral and central BP, as well as measures of vascular function were noted at 16 and 52 weeks. However, among patients with uncontrolled HTN and hypertensive heart disease, adjunct vitamin D does not provide benefit beyond antihypertensive therapy to vascular function.