Hypovitaminosis D in patients with heart failure: effects on functional capacity and patients' survival

Chronic heart failure is a major cause of morbidity and mortality, but its prognosis remains poor. Vitamin D hormone has many extra-skeletal functions including a positive impact on the cardiovascular system, and has been proposed for mortality risk evaluation in heart failure patients. The aim of the present study was to evaluate vitamin D status in heart failure patients, measured by high performance liquid chromatography coupled with mass spectrometry and to correlate serum 25 hydroxy-vitamin D (25OHD) levels with functional (peak VO2%) and mortality (Metabolic Exercise Cardiac Kidney Index) heart failure parameters. We enrolled 261 consecutive patients diagnosed with heart failure; all patients underwent a comprehensive clinical and biochemical characterization, and serum 25OHD levels were measured by high performance liquid chromatography coupled with mass spectrometry. Cardiopulmonary test parameters and Metabolic Exercise Cardiac Kidney Index of mortality risk were measured in all patients. Serum 25OHD levels ranged between 2 and 45 ng/ml (mean 17 ± 9 ng/ml); most patients (87%) showed hypovitaminosis D, and 25% showed severe vitamin D deficiency (serum 25OHD < 10 ng/ml). Patients with 25OHD < 10 ng/ml had significantly lower cardiopulmonary test VO2/kg, peak VO2% and significantly higher N-terminalproBrain natriuretic peptide and Metabolic Exercise Cardiac Kidney Index, than patients with 25OHD > 10 ng/ml. Patients with peak VO2% < 50% showed significantly lower 25OHD compared to those with peak VO2% > 50%. There was a significant, positive correlation (r = 0.16, p = 0.008) between 25OHD levels and peak VO2%, and an inverse correlation with Metabolic Exercise Cardiac Kidney Index (r = -0.21, p < 0.001), even when adjusted for age, Body Mass Index, MDRD, N-terminalproBrain natriuretic peptide. In conclusion, our findings show that vitamin D levels are associated with functional and mortality heart failure prognosis parameters.