Omega-3 and Risk of atrial fibrillation: Vagally-mediated double-edged sword

Area of Science:

• Cardiovascular Research
• Nutritional Science
• Pharmacology

Background:

• Conflicting results exist regarding omega-3 fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and atrial fibrillation (AF) risk.
• Understanding the dose-dependent effects and potential mediators is crucial for clinical practice.

Purpose of the Study:

• To clarify the effects of marine omega-3 intake on the risk of developing atrial fibrillation (AF).
• To explore the role of vagal tone as a potential mediator in the relationship between omega-3s and AF risk.

Main Methods:

• Systematic review of randomized clinical trials (RCTs), epidemiology studies, and meta-analyses.
• Literature search using PubMed with keywords: atrial fibrillation, omega-3, EPA, DHA, and vagal tone.
• Analysis of dose-response relationships and exploration of vagal tone's influence.

Main Results:

• Meta-analyses of RCTs (8 studies, 83,112 participants) showed a 24% increased AF risk with DHA/EPA treatment (4.0% vs 3.3%), dose-dependently.
• Higher pharmaceutical doses (1800-4000 mg/d) significantly increased AF risk (approx. 50%), while lower doses (approx. 1000 mg/d) showed a smaller increase (approx. 12%).
• Observational studies (17 studies, 54,799 participants) indicated that higher dietary intake or blood levels of DHA/EPA were associated with decreased AF risk (max reduction 12% at ~650 mg/d).
• Omega-3s can dose-dependently increase vagal tone, potentially explaining the biphasic relationship observed between DHA+EPA and AF risk.

Conclusions:

• Dietary omega-3 consumption is associated with a reduced risk of atrial fibrillation.
• Pharmaceutical administration of omega-3s increases AF risk in a dose-dependent manner.
• Vagal tone modulation may mediate the observed relationship between omega-3s and AF risk.