Omega-3 supplementation may increase risk of AF in post-MI patients

Omega-3 fatty acids popularly known as "healthy fats" that is popularly known to benefit heart health. One key benefit of omeg-3 supplementation is known to lower triglycerides levels. Specific types of omega-3s include DHA and EPA (found in seafood) and ALA (found in plants).

However recent randomized clinical trials have raised concerns regarding potential off target adverse effects from supplementation of n-3 polyunsaturated fatty acids (PUFA) on atrial fibrillation (AF) risk.

The OMEMI Trial by Peder L. Myhre and team suggests that supplementation of n-3 PUFA post MI increases the risk of ‘micro-AF’ and AF, and increases in EPA seems to be an important mediator of the treatment effect from n-3 PUFA on the risk of AF. The trial is published in journal Clinical Nutrition.

Researchers aimed to assess risk and potential mediators of AF and ‘micro-AF’ from n-3 PUFA in post-myocardial infarction (MI) patients. The OMEMI trial, included 70–82 y. o. patients with a recent MI were randomized to 1.8 g/day of eicosapentaenoic-/docosahexaenoic acid (EPA/DHA) or placebo (corn oil) for two years. New-onset AF and ‘micro-AF’ was recorded by clinical detection and by screening with Zenicor thumb-ECG (adjudicated by blinded investigators). Serum EPA and DHA were measured at baseline and study end.

The key findings of the study are

• At baseline, 759 of 1014 (75%) patients had no AF history. These patients were aged 75 ± 4 years and 71% were male.

• During follow-up, 43 patients developed new-onset AF (39 clinically-detected and 4 by thumb-ECG screening).

• In addition, 27 patients had episodes of micro-AF, yielding a total of 70 patients with new-onset AF or ‘micro-AF’.

• In the n-3 PUFA group 46 (11.9%) had AF/’micro-AF’ (28 AF, 18 ‘micro-AF’) and in the placebo group 24 (6.5%) had AF/micro-AF (15 AF, 9 micro-AF); HR 1.90 (95%CI 1.16–3.11), P = 0.011.

• Changes in serum EPA (but not DHA) mediated the effect from n-3 PUFA on AF risk, explaining 65% of the association.

Researchers concluded that “Supplementation of n-3 PUFA post MI increases the risk of ‘micro-AF’ and AF, and increases in EPA seems to be an important mediator of the treatment effect from n-3 PUFA on the risk of AF.”

Reference: Peder L. Myhre a b, Trygve Berge b c 1, Are A. Kalstad b d, Sjur H et al; Omega-3 fatty acid supplements and risk of atrial fibrillation and ‘micro-atrial fibrillation’: A secondary analysis from the OMEMI trial, September 2023, DOI:https://doi.org/10.1016/j.clnu.2023.07.002.