Polyunsaturated fatty acids for prevention of atrial fibrillation: a 'fishy' story

This editorial refers to ‘ n -3 Polyunsaturated fatty acids for the prevention of arrhythmia recurrence after electrical cardioversion of chronic persistent atrial fibrillation: a randomized, double-blind, multicentre study’ by L. Bianconi et al ., on page 174 Several reports from population-based surveys and large randomized clinical trials have shown a remarkable 45–68% reduction in the rates of sudden cardiac death (presumably arrhythmic) with high dietary fish consumption or omega-3 polyunsaturated fatty acid (PUFA) supplements and have prompted interest in employing PUFAs as antiarrhythmic drugs.1,2 Three randomized clinical trials in patients at particularly high risk of sudden arrhythmic death, i.e. patients with internal cardioverter-defibrillators (ICDs) for secondary prevention, have followed, but surprisingly only one of these studies has shown any protective effect of PUFAs and one other even hinted at their proarrhythmic potential in some subgroups.3 Nevertheless, the quest into the antiarrhythmic effects of PUFAs has continued in patient populations with atrial fibrillation (AF).There appears to be a good rationale behind this. Universal constituents of biological membranes, PUFAs—mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—regulate membrane fluidity, modulate the activity of multiple membrane proteins, and counteract the arrhythmogenic effects of atrial stretch.4 Other potential antifibrillatory mechanisms include anti-inflammatory and antioxidant actions, mitigation of endothelial dysfunction, and regulation of profibrotic activity of mitogen-activated protein kinases and matrix metalloproteinases.5 In addition, PUFAs may reduce the adverse impact of underlying heart disease, e.g. by vasodilatation, blood pressure reduction, and improved contractile function of the myocardium. However, most relevant antiarrhythmic action of PUFAs in AF probably results from their direct electrophysiological effects on several ion channels, such as I Na, I Kur, I KAch, I to, and I Ca,L currents, and the Na+/Ca2+ exchanger.6,7The effects of PUFAs on structural …