Both clinical and experimental evidence have suggested an anti-arrhythmic effect of long-chain n-3 polyunsaturated fatty acids (n-3-PUFAs) in fish oil.  However, the effect of n-3-PUFAs on atrial arrhythmias such as postoperative atrial fibrillation (AF) remain uncertain.  The Omega-3 Fatty Acids for Prevention of Post-operative Atrial Fibrillation (OPERA) trial was designed to test whether perioperative n-3-PUFA supplementation could reduce postoperative AF.

 1516 patients scheduled for cardiac surgery in 28 centres in the United States, Italy, and Argentina were enrolled between August 20120 and June 2012.  Patients were randomised to receive fish oil or placebo, with preoperative loading of 10g over 3 to 5 days, followed postoperatively by 2g per day until hospital discharge or postoperative day first, whichever was sooner.  Patients not in sinus rhythm at the outset were excluded.  The main outcome measure was the occurrence of postoperative AF lasting longer than thirty seconds.

 233 (30.7%) of patients assigned to placebo developed postoperative AF compared to 227 (30.0%) assigned to n-3 PUFAs (P=.74).  The number of postoperative AF episodes also did not differ between the placebo and PUFA groups, nor did the incidence of AF that was sustained, symptomatic, or treated (P=.70).  However, supplementation with n-3 PUFAs was generally well tolerated, and there was no suggestion of increased bleeding or serious adverse events.

Conclusions:

 This trial found no evidence that preoperative supplementation with n-3 PUFAs, compared with placebo, could reduce the risk of postoperative AF in patients undergoing cardiac surgery.

•  Mozaffarian D, Marchioli R, Macchia A et al.  Fish Oil and Postoperative Atrial Fibrillation.  The Omega-3 Fatty Acids for Prevention of Post-Operative Atrial Fibrillation (OPERA) Randomized Trial.  JAMA 2012;308(19):2001-2011.