Serum 25-hydroxyvitamin D concentration is associated with functional capacity in older adults with heart failure

Background Vitamin D is a fat-soluble hormone necessary for calcium homeostasis. Recently, studies have demonstrated that vitamin D may be important to the health of the cardiovascular system. Methods Adults >= 50 years of age with heart failure were recruited for assessment of serum 25-hydroxyvitamin D (25OHD) concentrations. Cardiopulmonary exercise testing was used to assess functional capacity. Proximal muscle strength was evaluated with a Biodex leg press (Biodex, Shirley, NY), and health status was assessed with the Kansas City Cardiomyopathy Questionnaire. Univariate associations between physical performance and health status measures and 25OHD followed by a linear regression model were used to study associations, adjusting for other potential explanatory variables. Results Forty adults 67.8 +/- 10.9 years of age (55% women and 57.5% African American) with mean ejection fraction 40% were analyzed (New York Heart Association class II in 70% and class III in 30%). Comorbidities included 77.5% hypertension and 47.5% diabetes. The mean 25OHD concentration was 18.5 +/- 9.1 ng/mL, and mean peak VO(2), 14 +/- 4 mL/kg/min. In univariate regression analysis, 25OHD was positively associated with peak VO(2) (P=.045). Multivariable regression analysis sustained positive association between 25OHD and peak VO(2) (P=.044) after adjusting for age, race, and respiratory exchange ratio (adjusted R(2)=0.32). Association between proximal muscle strength with the 25OHD concentration was not significant. The Kansas City Cardiomyopathy Questionnaire physical limitation domain score was negatively associated with 25OHD (P=.04) but was not sustained in multivariable analysis. Conclusions 25-Hydroxyvitamin D may be an important marker or modulator of functional capacity in patients with heart failure. Randomized controlled trials are needed to assess the effect of vitamin D repletion on functional performance. (Am Heart J 2010;160:893-9.)