Omega-3 fatty acids, particularly EPA and DHA found in fish oil, have been investigated for their potential role in the management of arrhythmias. The scientific basis for this comes from both preclinical and clinical studies suggesting that omega-3s can stabilize cardiac cell membranes, modulate ion channels, and reduce inflammation, all of which could theoretically reduce arrhythmic risk. Early observational studies and animal models indicated a possible antiarrhythmic effect, leading to widespread interest and use.

However, large randomized controlled trials (RCTs) in recent years have produced mixed or largely negative results regarding omega-3s' efficacy in preventing arrhythmias, especially in secondary prevention (e.g., after myocardial infarction or in patients with implantable cardioverter-defibrillators). Meta-analyses suggest only a small or uncertain benefit for preventing atrial fibrillation or sudden cardiac death. The American Heart Association acknowledges that omega-3s may have modest benefits for some cardiac outcomes, but does not strongly endorse them specifically for arrhythmia prevention or treatment.

In summary, while there is a scientific rationale and some supportive early evidence, the overall quality and consistency of evidence is limited. Therefore, omega-3s are not considered a primary, evidence-based therapy for arrhythmia, but may be used as adjuncts in select cases.