CORRESPONDENCE: LETTER TO THE EDITOR
Effects of N-3 Fatty Acids on Postoperative Atrial Fibrillation Following Coronary Artery Bypass Surgery
Panagiotis Korantzopoulos, MD*,
Theofilos M. Kolettis, MD, PhD and
John A. Goudevenos, MD, FACC, FESC
* Department of Internal Medicine, Division of Cardiology, University of Ioannina Medical School, 45110 Ioannina, Greece (Email: pkor{at}oneway.gr).
We read with considerable interest the recent contribution by Calò et al. (1) about the reduced incidence of postoperative atrial fibrillation (AF) after administration of n-3 polyunsaturated fatty acids (PUFAs) in patients undergoing coronary artery bypass surgery (CABG). Even though the investigators discuss the potential role of inflammation in this setting we consider that some important issues merit further clarification.
First, 19 of the studied patients were subjected to off-pump surgery, a procedure considered to be associated with a lesser oxidative and inflammatory response (2). Bearing in mind the hypothesis that postoperative AF may be reduced by off-pump CABG (3), it would be meaningful to examine whether there was a difference in the incidence of postoperative AF in this subset of patients.
In addition, it has been observed that the peak incidence of AF on the second or third postoperative day coincides with the peak of inflammatory markers such as C-reactive protein (CRP) and complement-CRP complexes (4). Recently, Abdelhadi et al. (5) confirmed this association, demonstrating a more pronounced and prolonged increase in white blood cell counts of patients who developed postoperative AF. Thus, to validate the anti-inflammatory effects of PUFAs someone could investigate the variation of simple inflammatory indexes in the postoperative period. If Calò et al. have some available data on this issue it would be of interest to perform comparisons between the two groups.
Of note, more than one-half the total study population was taking statins perioperatively (1). Even though there were no differences regarding statin administration between the studied groups, the investigators could mention some data on potential differences in the incidence of postoperative AF within each group. Statins may exert beneficial pleiotropic effects on atrial remodeling, reducing the burden of the arrhythmia. It has also been indicated that statin therapy reduces the incidence of arrhythmias after CABG, although no specific data on AF was reported (6). Recently, Auer et al. (7) demonstrated a reduced incidence of AF after cardiac operation in patients receiving statins, but 44.7% of these had been subjected to valve surgery.
Accumulating evidence suggests that inflammation augments oxidative stress and vice versa, whereas oxidative stress seems to play an important role in atrial remodeling (2,8). Specifically, it has been shown that oral vitamin C administration significantly reduces the incidence of postoperative AF in CABG patients (8). Taking into account that PUFAs can attenuate oxidative stress in humans (9), it is reasonable to assume that their antioxidant action may contribute to their favorable effect on postoperative AF.
Finally, we concur with the view of Calò et al. that administration of PUFAs merits further evaluation in other forms of AF, but, as suggested by a recent study that reported no association between PUFA consumption from fish and the risk of AF (10), careful selection of the studied population should be performed.
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1. Calò L, Bianconi L, Colivicchi F, et al. N-3 fatty acids for the prevention of atrial fibrillation after coronary artery bypass surgery. A randomized, controlled trial J Am Coll Cardiol 2005;45:1723-1728.[Abstract/Free Full Text]2. Matata BM, Sosnowski AW, Galinanes M. Off-pump bypass graft operation significantly reduces oxidative stress and inflammation Ann Thorac Surg 2000;69:785-791.[Abstract/Free Full Text] 3. Archbold RA, Curzen NP. Off-pump coronary artery bypass graft surgerythe incidence of postoperative atrial fibrillation. Heart 2003;89:1134-1137.[Abstract/Free Full Text] 4. Bruins P, te Velthuis H, Yazdanbakhsh AP, et al. Activation of the complement system during and after cardiopulmonary bypass surgerypostsurgery activation involves C-reactive protein and is associated with postoperative arrhythmia. Circulation 1997;96:3542-3548.[Abstract/Free Full Text] 5. Abdelhadi RH, Gurm HS, Van Wagoner DR, Chung MK. Relation of an exaggerated rise in white blood cells after coronary bypass or cardiac valve surgery to development of atrial fibrillation postoperatively Am J Cardiol 2004;93:1176-1178.[CrossRef][Web of Science][Medline] 6. Dotani MI, Elnicki M, Jain AC, Gibson CM. Effect of preoperative statin therapy and cardiac outcomes after coronary bypass grafting Am J Cardiol 2000;86:1128-1130.[CrossRef][Web of Science][Medline] 7. Auer J, Weber T, Berent R, et al. European Society of Cardiology Annual Congress, Munich Use of HMG-coenzyme-a–reductase inhibitors (statins) and risk reduction of atrial fibrillation after cardiac surgeryresults of the SPAAF study—a randomised placebo-controlled study (abstr). 2004:353Abstract book. 8. Carnes CA, Chung MK, Nakayama T, et al. Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation Circ Res 2001;89:e32-e38.[Abstract/Free Full Text] 9. Mori TA, Woodman RJ, Burke V, et al. Effect of eicosapentaenoic acid and docosahexaenoic acid on oxidative stress and inflammatory markers in treated hypertensive type 2 diabetic patients Free Radic Biol Med 2003;35:772-781.[CrossRef][Web of Science][Medline] 10. Frost L, Vestergaard P. N-3 fatty acids consumed from fish and risk of atrial fibrillation or flutterthe Danish Diet, Cancer, and Health Study. Am J Clin Nutr 2005;81:50-54.[Abstract/Free Full Text]
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