14 November 2011
Effect of Dietary Fish Oil on Atrial Fibrillation after Cardiac Surgery
Farquarharson , A. L. et al., American Journal of Cardiology , 108: 851-856 , 2011
Discipline of Medicine, University of Adelaide and Dept. of Cardiology, Royal Adelaide Hospital, Adelaide, Australia
Atrial fibrillation is a relatively common heart rhythm disorder which often occurs as a result of cardiac surgery. It is associated with extended stays in the intensive care unit (ICU) and the overall duration of hospitalization as well as increased mortality. Since an anti-arrhythmic effect of EPA/DHA omega-3 fatty acids has been indicated in multiple animal and some human studies, the present investigation was conducted to evaluate the potential beneficial effects of supplementation with omega-3 prior to cardiac surgery on the post-surgical outcomes. Patients (200) scheduled for coronary artery bypass surgery (CABG) or valve repair were randomly assigned to receive a placebo capsule lacking omega-3 (control group) or 2.7 gm EPA plus 1.9 gm DHA daily for 21 days prior to surgery. Supplementation was maintained for 6 days after surgery or until discharge from hospital (whichever came first).
The overall incidence of in-hospital atrial fibrillation (AF) was found to be 48 % for the control group and 37 % in those given EPA/DHA with no statistically-significant difference between the two groups. A trend for a delayed time to occurrence of AF (by 29-34 %) was found in the omega-3 group as compared to controls which did not quite reach statistical significance. A statistically-significant lesser period of time in the ICU post-surgery was found for patients previously given omega-3 (average of 67 hours) as compared to those in the control group (average of 95 hours). The omega-3 group also showed much higher levels of omega-3 in samples of cardiac tissue when taken at the time of surgery for fatty acid analyses (EPA plus DHA averaged at 8.14 % of total fatty acids in heart tissue phospholipid for the omega-3 group as compared to only 4.94 % for the controls). The authors concluded that the lessened period of time spent in the ICU following cardiac surgery resulting from the pre-surgical supplementation with EPA/DHA is likely to be significant for health costs because of the high costs associated with intensive care.
Dr. Holub’s Comments :
It is of interest to note that, despite the fact that the omega-3 supplementation contained much more EPA than DHA, the DHA levels in the heart tissue samples (analyzed in the phospholipid fraction) from the omega-3 patients had three times more DHA than EPA (6.10 % as DHA and only 2.03 % as EPA). It is possible that the beneficial effects seen with omega-3 supplementation could be mediated more by the enrichment of DHA in cardiac tissue. However, multiple factors over and above decreased AF due to omega-3 enrichment in cardiac tissue could likely be responsible for the reduced time of patients in the ICU following surgery. The various benefits of omega-3 which are external to their accumulation in cardiac tissue might be due to cellular accumulations of EPA and/or DHA and the formations of their bio-active metabolites (eg, anti-inflammatory resolvins , protectins , other products).