Relation of Serum 25-Hydroxyvitamin D to Heart Rate and Cardiac Work (from the National Health and Nutrition Examination Surveys)

Vitamin D may protect against cardiovascular disease, but its association with cardiac function is unclear. The aim of this study was to examine the associations of serum 25-hydroxyvitamin D (25[OH]D) with heart rate, systolic blood pressure, and the rate pressure product (RPP). Data analyses were carried out on 27,153 participants aged >= 20 years, with measurements of serum 25(OH)D, heart rate (from radial pulse), and systolic blood pressure, in the National Health and Nutrition, Examination Surveys (NHANES) carried out from 1988 to 1994 and from 2001 to 2006. RPP was calculated as heart rate times systolic blood pressure. Results were adjusted for age, gender, race or ethnicity, body mass index, physical activity, tobacco smoking, co-morbidities, and blood pressure treatment. Compared to participants with 25(OH)D >= 35 ng/ml, the adjusted mean +/- SE heart rate was significantly (p <0.001) higher, by 2.1 +/- 0.6 beats/min, in participants with 25(OH)D <10.0 ng/ml, while mean systolic blood pressure was 1.9 +/- 0.8 mm Hg higher (p <0.05) for participants with 25(OH)D <10.0 ng/ml and 1.7 +/- 0.6 mm Hg higher (p <0.01) for those with 25(OH)D of 10.0 to 14.9 ng/ml. As a consequence, adjusted mean RPP was 408 +/- 110 beats/min . mm Hg higher (p <0.001) for participants with 25(OH)D <10.0 ng/ml and 245 +/- 80 beats/min . mm Hg higher (p <0.01) for participants with 25(OH)D of 10.0 to 14.9 ng/ml, compared to those with 25(OH)D 35 ng/ml. In conclusion, these results show that low serum 25(OH)D levels are associated with increased heart rate, systolic blood pressure, and RPP and suggest that low vitamin D status may increase cardiac work. Vitamin D intervention studies are required to confirm these findings. (C) 2010 Elsevier Inc. All rights reserved. (Am J Cardiol 2010;105:122-128)