METCALF and COLLEAGUES, (1)1] Rheumatology Unit, Royal Adelaide Hospital, Adelaide, Australia  Centre for Heart Rhythm Disorders, Discipline of Medicine, University of Adelaide, Adelaide, Australia; (2)1] Department of Physiology, School of Health Sciences, University of Iceland, Reykjavik, Iceland  Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland; (3)Division of Nephrology, Internal Medicine Services, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland; (4)Data Management and Analysis Centre, Discipline of Public Health, University of Adelaide, Adelaide, Australia; (5)1] Centre for Heart Rhythm Disorders, Discipline of Medicine, University of Adelaide, Adelaide, Australia  Cardiovascular Investigation Unit, Royal Adelaide Hospital, Adelaide, Australia; (6)1] Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland  Division of Cardiology, Internal Medicine Services, Cardiovascular Research Center, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland; (7)FOODplus Research Centre, School of Agriculture Food and Wine, University of Adelaide, Adelaide, Australia; (8)Rheumatology Unit, Royal Adelaide Hospital, Adelaide, Australia; (9)1] Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland  Division of Nephrology, Internal Medicine Services, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland; (10)Centre for Heart Rhythm Disorders, Discipline of Medicine, University of Adelaide, Adelaide, Australia examined relationships between levels of red blood cell (RBC) n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) and the incidence of postoperative atrial fibrillation (POAF).
Randomised controlled trials (RCTs) evaluating the effect of fish oil supplementation on postoperative atrial fibrillation (POAF) following cardiac surgery have produced mixed results. In this study, we examined relationships between levels of red blood cell (RBC) n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) and the incidence of POAF.
The authors used combined data (n=355) from RCTs conducted in Australia and Iceland. The primary end point was defined as POAF lasting >10 min in the first 6 days following surgery. The odds ratios (ORs) for POAF were compared between quintiles of preoperative RBC n-3 LC-PUFA levels by multivariable logistic regression.
Subjects with RBC docosahexaenoic acid (DHA) in the fourth quintile, comprising a RBC DHA range of 7.0-7.9%, had the lowest incidence of POAF. Subjects in the lowest and highest quintiles had significantly higher risk of developing POAF compared with those in the fourth quintile (OR=2.36: 95% CI; 1.07-5.24 and OR=2.45: 95% CI; 1.16-5.17, respectively). There was no association between RBC eicosapentaenoic acid levels and POAF incidence.
The results suggest a 'U-shaped' relationship between RBC DHA levels and POAF incidence. The possibility of increased risk of POAF at high levels of DHA suggests an upper limit for n-3 LC-PUFAs in certain conditions.
Metcalf RG(1), Skuladottir GV(2), Indridason OS(3), Sullivan TR(4), Bjorgvinsdottir L(2), Sanders P(5), Arnar DO(6), Gibson RA(7), Heidarsdottir R(2), Cleland LG(8), Palsson R(9), Farquharson AL(10), Young GD(5), James MJ(1). U-shaped relationship between tissue docosahexaenoic acid and atrial fibrillation following cardiac surgery. Eur J Clin Nutr. 68(1):114-8. Jan 2014. doi: 10.1038/ejcn.2013.215. Epub Oct 30 2013.