In a recent study in the journal Circulation, researchers from the Smidt Heart Institute conducted a meta-analysis that included seven randomized, controlled trials (RCTs). The researchers utilized MEDLINE and Embase databases and searched for articles and abstracts published between January 1, 2012, and December 31, 2020, in addition to a meta-analysis of large cardiovascular (CV) RCTs published in 2019.

In this meta-analysis, all studies reviewed CV outcomes related to marine omega-3 fatty acids that reported AF results as either a prespecified outcome, adverse event, or hospitalization cause. All trials analyzed included at least 500 patients and had a median follow-up of at least 1 year. RCTs specifically examining shorter-term effects of omega-3 fatty acids on recurrent AF in patients with established AF or postoperative AF were not included. The hazard ratio for the reported AF outcomes within each trial was meta-analyzed using a random-effects model with Knapp-Hartung adjustment and evaluated a dose-response relationship with a meta-regression model.

The researchers indicated that of the 4,049 screened records, seven studies were included in the meta-analysis. Of those, five were already detected in a previous meta-analysis of CV RCTs. Among the 81,210 patients from seven trials, 58,939 (72.6%) were enrolled in trials testing ≤1 g per day (g/d) and 22,271 (27.4%) in trials testing >1 g/d of omega-3 fatty acids. The average age was 65 years, and 31,842 (39%) patients were female. The weighted average follow-up was 4.9 years.

The researchers found that patients who took >1 g/d of omega-3 fatty acids had a 49% increased risk of developing AF, compared with just 12% of patients who took ≤1 g/d  of the supplement. The researchers concluded that in RCTs examining CV outcomes, marine omega-3 supplementation was linked to a heightened risk of AF. The risk appeared to be greater in trials testing >1 g/d.

In a press release, Christine M. Albert, MD, MPH, a professor of Cardiology and chair of the Department of Cardiology in the Smidt Heart Institute, stated, "Our goal was to bring clarity, answers and actionable information to the broader medical field and to patients. In this instance, the results suggest that there may not be a straightforward answer to, 'Is fish oil good or bad for atrial fibrillation?' but instead, the answer may depend on the dose." 

As a result of the findings, Dr. Albert advised that if clinicians offer high-dose omega-3 fatty acid supplements, they should first discuss the potential risk of developing AF, and patients should be informed about the potential signs and symptoms of the condition so an early diagnosis can be made and coupled with appropriate treatment.

Dr. Albert also stated, "Researchers should systematically monitor patients for atrial fibrillation and related adverse outcomes to better define risk-to-benefit ratios in studies examining the effects of omega-3 fatty acid supplements. For patients, the risk of developing atrial fibrillation appears to be relatively small for those taking one gram or less of fish oil per day. Taking more than one gram of fish oil per day is something you should only do following your doctors' advice."

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

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