More evidence has emerged to discourage people from using marine omega-3 fatty acids or vitamin D for the primary prevention of atrial fibrillation (AF).
A large-scale RCT comprised 25,000 adults, ≥50 years, without prior cardiovascular disease (CVD), cancer or AF. Participants were randomised to either fatty acids EPA-DHA and vitamin D, EPA-DHA and placebo, vitamin D and placebo, or two placebos.
The US study, published in JAMA, found that the primary end point of incident AF occurred in 3.6% of the study population after 5.2 years of treatment and follow-up
There was no significant difference in AF rates between the four groups.
Incident AF occurred in 3.7% participants randomised to EPA-DHA and 3.4% randomised to placebo (HR, 1.09; 95% CI, 0.96-1.24; p = 0.19).
“For the secondary outcomes of incident paroxysmal AF and non-paroxysmal AF, the HRs were 1.07 (95% CI, 0.90-1.27; P = .46) and 1.11 (95% CI, 0.90-1.37; P = .32), respectively,” the study said.
Similarly, incidence AF occurred in 3.7% of participants randomised to vitamin D and 3.4% of those randomised to placebo.
“When analysed according to the 4 treatment groups, compared with participants randomised to both placebos, the HR for incident AF for those randomised to EPA-DHA and placebo was 1.16 (95% CI, 0.96-1.40; P = .13), for those randomised to vitamin D3 and placebo was 1.16 (95% CI, 0.96-1.40; P = .13), and for those randomised to vitamin D3 and EPA-DHA was 1.20 (95% CI, 0.99-1.45; P = .06).”
“Overall, these findings do not support the use of supplemental EPA-DHA or vitamin D3 for the primary prevention of AF and provide reassurance regarding lack of a major risk of AF incidence associated with these commonly used supplements at these doses,” the study said.
An editor’s note in JAMA said there was growing but inconsistent evidence about the risk of AF with omega-3 fatty acids.
“Considered together, the data from the 4 trials suggest, but do not prove, that there may be a dose-related risk of AF with omega-3 fatty acid intake.”
“At a dose of 4.0 g/d, there was a highly statistically significant increase in risk (nearly a doubling). With an intermediate dose of 1.8 g/d, the increase in risk (hazard ratio, 1.84) did not achieve statistical significance, and with a standard daily dose of 840 mg/d, there was no apparent increase in risk (although the data were consistent with as much as a 24% increase in risk).”
He said patients who choose to take omega-3 fatty acids, especially in high doses, should be informed of and followed up for the risk of AF.