TOPLINE:
a post hoc analysis from a randomized trial conducted in Finland suggests.
METHODOLOGY:
- Observational studies have suggested that vitamin D deficiency is associated with increased risk for AFib, but few randomized trials have looked at the effect of vitamin D supplementation on AFib incidence in healthy people.
- The study, a post hoc analysis from a trial that explored the effects of vitamin D3 supplementation on incidence of cardiovascular diseases and cancer, included 2,495 vitamin D–sufficient healthy older adults, mean age 68.2 years, of whom 43% were women.
- Participants had been randomized to one of three groups in which they received vitamin D3 at either 1,600 IU/day or 3,200 IU/day, or placebo.
- Serum 25(OH)D3 concentrations were measured and data on incident AFib were gathered from national health records.
TAKEAWAY:
- Atrial fibrillation was diagnosed in 190 participants.
- Over a follow-up averaging 4.1 years, risk for incident AFib was reduced by 27% for participants who received the 1,600 IU/day dose, compared with placebo; hazard ratio, 0.73 (95% confidence interval, 0.52-1.02; P = .07), and by 32% for those in the 3,200 IU/day arm; HR, 0.68 (95% CI, 0.48-0.96; P = .03).
- The incident-AFib risk was reduced by 30% in a comparison of the two vitamin D groups combined versus the placebo group; HR, 0.70 (95% CI, 0.53-0.94; P = .02).
- After exclusion of 122 participants who reported being on antiarrhythmic medications at baseline, the 1,600 IU/day group showed a significant 27% reduction in risk for AF (95% CI, 4%-58%; P = .03) and the 3,200 IU/day group a nonsignificant 30% (95% CI, 5%-53%; P = .08) reduction in risk.
IN PRACTICE:
High-dose vitamin D3 supplementation may reduce incidence of AFib in a generally healthy, largely vitamin D–sufficient elderly population, the authors proposed. Additional controlled trials are needed, especially in diverse populations.
STUDY DETAILS:
The study was conducted by Jyrki K. Virtanen, PhD, University of Eastern Finland, Institute of Public Health and Clinical Nutrition, Kuopio, and colleagues. It was published in the American Heart Journal.
LIMITATIONS:
Atrial fibrillation was not prespecified as a primary outcome, and the results differ from those of other randomized controlled trials. Information on type of AFib (whether paroxysmal or nonparoxysmal, for example) wasn’t available nor were participants’ history of AFib. All participants were White and from Finland, limiting generalizability of the results.
DISCLOSURES:
The study was supported by the Academy of Finland, University of Eastern Finland, the Juho Vainio Foundation, Medicinska Understödsföreningen Liv och Hälsa, Finnish Foundation for Cardiovascular Research, Finnish Diabetes Research Foundation, and the Finnish Cultural Foundation. One coauthor disclosed receiving grants from the National Institutes of Health and Mars Edge. Another coauthor disclosed receipt of a grant from Orion. The other authors disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.