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JAMA Study Clarifies Fish Oil AFib Effects

CHICAGO—A Harvard-led research team has found short-term fish oil supplementation before and after cardiac surgery did  not reduce the risk of  post-operative atrial fibrillation (AF). Results of the double blind, placebo-controlled, randomized trial, dubbed the Omega-3 Fatty Acids for Prevention of Post-operative Atrial Fibrillation (OPERA) trial, were published online ahead of print by JAMA.

The trial featured 1,516 surgical patients (mean age of 64 years) from cardiac centers in the United States, Italy and Argentina who were enrolled in the trial between August 2010 and June 2012, and were not regular fish oil users. The subjects were randomized to receive either one capsule of fish oil (containing at least 840 mg of omega-3 fatty acids as ethyl esters) or placebo preoperatively (10g over three to five days or 8g over two days) and postoperatively (2g daily until hospital discharge or 10 days maximum).  Researchers looked primarily for post-op AF occurrence longer than 30 seconds, in addition to monitoring secondary outcomes including  AF episodes longer than one hour (symptomatic or treated with cardioversion), post-op AF without atrial flutter, time to first post-op AF episode, number of AF episodes per patient,  hospital utilization and adverse cardiac events, including 30-day mortality and bleeding.

The incidence rate of post-op AF was about the same in both fish oil and placebo groups, and there was no significant difference between the two treatment groups relative to any of the secondary outcomes. However, supplementation with fish oil was well-tolerated across the study groups and did not increase risk of bleeding or serious adverse events.

While the published conclusion was preoperative supplementation with fish oil in cardiac surgery patients did not affect risk of post-operative AF, lead researcher Dariush Mozaffarian, MD, DrPH, Harvard School of Public Health, said fish oil may simply not be powerful enough in the short-term or in other situations in which arrhythmias are already established, such as preventing recurrence in patients who already have AF. "The most promising strategy would be long-term use of fish oil to prevent the initial onset of AF later in life—this is the most common arrhythmia in older adults, occurring in at least 1 in 5 Americans after age 65," he suggested. "A large randomized control trial (RCT) in older adults is needed to address this question."

Harry Price, technical director for the Global Organization for EPA and DHA Omega-3 (GOED), said the trial was well-designed and cautiously optimistic in its reporting of secondary findings. Despite the clear conclusion preoperative loading of omega-s did not reduce postoperative AF, Price said the outcome was very specific and should not be overgeneralized. "It's possible that longer-term consumption of omega-3 [fatty acids] prior to surgery would be beneficial," he reasoned, adding this theory would obviously need to be tested.  In addition, he noted there were some exciting secondary findings that approached significance and clearly warrant further investigation, including a decrease in in-hospital major adverse cardio events, as well as a decrease in death at 30 days, in the fish oil group, compared to placebo. "If these are not just chance findings, this is an instance when clinical significance can occur in the absence of statistical significance."

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