Among patients undergoing cardiac surgery, perioperative supplementation with omega-3 fatty acids does not appear to reduce the risk of postoperative atrial fibrillation (AF). An international investigation found that postoperative AF lasting longer than 30 seconds occurred in 30.7% of patients who received placebo and 30.0% of those who received omega-3 fatty acids.

Abstract: JAMA, November 21, 2012.