Background: The aim of this study was to investigate the effects of vitamin D (VD) on the interaction among functional, echocardiographic and hormonal parameters in patients with heart failure (HF) and VD deficiency.
Methods: In a randomized, double blind trial, 35 patients with HF and VD<20 ng/mL, received either 300,000 U of oral cholecalciferol followed by 50,000 U/month for 6 months, or placebo treatment.
Results: Changes in the 6 Minute Walking Test (6MWT) assessed at 3 and 6 months in treatment group was the primary end point. Secondary endpoints were echocardiographic and hormonal changes. The same targets were compared in treated and placebo groups as secondary endpoints. In the treatment group the 6MWT improved at 3 (from 210±104 mt to 225±94 mt; P=0.033) but not at 6 months (from 210±104 mt to 217±94 mt; P=0.288) while PTH dropped at 3 (from 76.8±50.5 to 50.2±20.3 pg/mL; P=0.025), but not at 6 months. 6MWT improvement was negatively related to baseline VD levels. Variation in 6MWT did not significantly differ among groups at 3 (13.6±23.3 vs. 3.6±17.3; P 0.175) and 6 months (12.1±31.4 vs. 0.2±23.2; P 0.225). Left atrial size increased in the placebo group (from 50.8±20.7 to 61.7±36.0 mL/m2; P=0.010). Other hormonal parameters remained unchanged.
Conclusions: In summary, the treatment of VD deficiency in patients with HF improved 6MWT after 3 months along with a decrease in PTH levels. However when compared with the placebo arm, treatment of VD deficiency did not influence the final outcomes.