Fish oil supplementation increases atrial fibrillation risk in some patients

Article written by Bruce Sylvester

Patients at high risk for cardiovascular disease (CVD) – or who already have established cardiovascular disease and elevated plasma triglycerides — who use omega-3 fatty acids supplementation have a significantly higher risk of developing atrial fibrillation when compared to non-users.

Researchers reported these findings on April 28, 2021 in the in European Heart Journal — Cardiovascular Pharmacotherapy.

“Currently, fish oil supplements are indicated for patients with elevated plasma triglycerides to reduce cardiovascular risk,” said author Salvatore Carbone, Ph.D,  of Virginia Commonwealth University, Richmond, Virginia. “Due to the high prevalence of elevated triglycerides in the population, they can be commonly prescribed. Of note, low dose omega-3 fatty acids are available over the counter, without the need for a prescription.”

Carbone added, “Our study suggests that fish oil supplements are associated with a significantly greater risk of atrial fibrillation in patients at elevated cardiovascular risk.”

As background, the authors noted that atrial fibrillation is the most prevalent sustained cardiac arrhythmia in the world. It is associated with high morbidity and mortality. Omega-3 fatty acids supplementation is widely used to reduce cardiovascular disease risk in patients with elevated plasma triglycerides. But the safety of this practice has been questioned due to outcomes in several cardiovascular trials of omega-3 fatty acids supplementation, which suggested a potential increase of atrial fibrillation  risk among omega-3 fatty acids subjects compared with placebo subjects.

The researchers conducted a meta-analysis of data from five relevant randomized and controlled clinical trials, to evaluate whether fish oil supplementation was consistently related to increased incidence of atrial fibrillation. The studies were all designed to study the effects of omega-3 fatty acid supplementation on cardiovascular outcomes.

All subjects in the meta-analysis had elevated triglycerides, and they had high risk for cardiovascular disease or were already diagnosed with established cardiovascular disease.

A total of 50,277 subjects had received fish oils or placebo and had been tracked for between 2 and 7.4 years. Fish oil dosing varied from 0.84 g to 4 g per day.

The investigators reported that omega-3 fatty acid supplementation was associated with a 37% increased risk of incident atrial fibrillation when compared with placebo. The difference was statistically significant (P < 0.001).

The authors said, “The results of this meta-analysis show that individuals at high risk for, or with established CVD and elevated plasma triglycerides treated with O3FA (omega-3 fatty acid supplementation) supplementation have a significantly higher incidence of AF events, compared to placebo. We also found no heterogeneity and no small study publication bias.”