Docosahexaenoic acid, but not eicosapentaenoic acid, supplementation reduces vulnerability to atrial fibrillation.

BACKGROUND The potential health benefits of ω-3 polyunsaturated fatty acids (PUFAs) usually are studied using a combination of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). This combination reduces vulnerability to experimentally induced atrial fibrillation (AF). It is unknown whether EPA and DHA have differential effects when taken alone. Using a model of pacing-induced atrial hemodynamic overload, we investigated the individual effects of EPA and DHA on vulnerability to AF and atrial remodeling. METHODS AND RESULTS Thirty-four dogs were randomized into 3 groups, all of which underwent simultaneous atrial and ventricular pacing at 220 beats per minute for 14 days. One group received purified DHA (≈1 g/d) orally for 21 days beginning 7 days before pacing began. Similarly, 1 group received ≈1 g/d purified EPA. In a third (control) group (No-PUFAs), 8 dogs received ≈1 g/d olive oil, and 12 were unsupplemented. Electrophysiological and echocardiographic measurements were taken at baseline and 21 days. Atrial tissue samples were collected at 21 days for histological and molecular analyses. Persistent AF inducibility was significantly reduced by DHA compared with No-PUFAs median [25-75 percentiles], 0% [0%-3%] for DHA versus 3.1% [2.2%-11%] for No-PUFAs; P=0.007) but not by EPA (3.4% [1.9%-8.9%]). DHA also reduced atrial fibrosis compared with No-PUFAs (11 ± 6% versus 20 ± 4%, respectively; P<0.05), whereas EPA did not (15 ± 5%; P>0.05). CONCLUSIONS DHA is more effective than EPA in attenuating AF vulnerability and atrial remodeling in structural remodeling-induced AF.