A randomized controlled trial of high dose vitamin D3 in patients with heart failure.

OBJECTIVE To investigate the effect of Vitamin D3 on physical performance in patients with HF. BACKGROUND HF is associated with functional decline and frailty. Vitamin D deficiency is associated with loss of muscle strength and poor outcomes in patients with HF. METHODS Sixty-four patients participated in a 6-month parallel design double blind RCT to test the hypothesis that oral vitamin D3 would improve physical performance. Vitamin D3 50,000 IU or placebo was given weekly; all received daily calcium. Patients were included regardless of EF and 25OHD ≤ 37.5 ng/ml. The primary outcome was peak VO2, and secondary outcomes were the 6MW, TGUG and knee isokinetic muscle strength. Between group comparisons were made using ANCOVA models that adjust for baseline measures. RESULTS Patients were age 65.9 ± 10.4 years old, 48% women, 64% African American, EF 37.6±13.9, 36% NYHA III, the remainder NYHA II. At baseline the vitamin D group 25OHD was 19.1 ± 9.3 ng/ml and increased to 61.7 ± 20.3 ng/ml; in the placebo group baseline 25OHD was 17.8 ± 9.0 ng/ml and decreased to 17.4 ± 9.8 ng/ml at 6 months (between groups p<0.001). There was no significant change from baseline to 6 months in peak VO2, 6MW, TGUG or isokinetic muscle strength. CONCLUSIONS Vitamin D3 did not improve physical performance for patients with HF despite a robust increase in serum 25OHD. Vitamin D repletion in patients with HF should conform to standard adult guidelines for vitamin D supplementation.