Impact of Vitamin D Supplementation on Cardiac Structure and Function

Overview

The VITamin D and OmegA-3 TriaL (VITAL; NCT 01169259) is a randomized clinical trial in 20,000 U.S. men and women investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or fish oil (1 gram of omega-3 fatty acids) reduces the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This ancillary study (VITAL-Echo) is being conducted among participants in VITAL and will examine whether vitamin D compared to placebo: (1) reduces left ventricular (LV) mass in elderly individuals as measured with 2-dimensional echocardiography and (2) improves LV systolic and diastolic function as measured with tissue Doppler echocardiography.

Recognition of the biological effects of vitamin D on cardiovascular function has been growing. The main objective of the parent trial (VITAL) is to evaluate the effects of vitamin D on cardiac events but is focused on atherothrombotic events and does not specifically address vitamin D effects on LV mass. In ambulatory individuals, LV mass is a key cardiac structural feature and increases in LV mass are frequently accompanied by diastolic dysfunction. This study leverages the existing infrastructure of the parent VITAL trial to perform cardiac imaging studies on a subset of subjects who will be randomized to vitamin D3 (n=500) or placebo (n=500). Echocardiography is a noninvasive, widely accessible tool to evaluate cardiac structure and function. Cardiac echo imaging visits will take place at baseline (pre-randomization), and then after 2 years, at the Massachusetts General Hospital (MGH). The acronym VITAL-Echo reflects the link to the parent VITAL trial and an ancillary investigation of vitamin D versus placebo on LV mass and function as measured by echocardiography. The effect of fish oil supplementation on these parameters will be evaluated as a secondary endpoint, thereby taking advantage of the factorial design of the parent trial.