A study (OPERA) investigating omega-3 pre-loading before open-heart surgery did not find a benefit in preventing post-operative atrial fibrillation.

“we did one big study where we were doing open-heart surgery on on people trying to pre-load them with omega-3 before open-heart surgery this was a dr moserfarian's study opera opera study and we're trying to prevent post-op afib by giving him a big load of omega-3 ahead of time because that was the theory at that time that we could prevent atrial fibrillation in people by giving them omega-3 before surgery and well it didn't work didn't make any difference”