(10-12-05) Dietary fish oil protects against stretch-induced vulnerability to atrial fibrillation in a rabbit model.

Ninio DM, Murphy KJ, Howe PR, Saint DA.

From the Discipline of Physiology, School of Molecular and Biomedical Science, University of Adelaide, Australia.

Dietary Fish Oil and Atrial Fibrillation. Introduction: Dietary fish oil is thought to reduce sudden cardiac death by suppressing ventricular arrhythmias but little is known about its impact on atrial arrhythmias. We examined the effect of dietary fish oil on the rabbit model of stretch-induced vulnerability to atrial fibrillation (AF). Methods and Results: Six-week-old rabbits were fed standard rabbit pellets supplemented with 5% tuna fish oil (n = 6) or supplemented with 5% sunflower oil (n = 6) for 12 weeks. Six rabbits raised on the standard diet were used as controls. In Langendorff-perfused hearts intraatrial pressures were increased in a stepwise manner and rapid burst pacing applied to induce AF at increasing intraatrial pressures until AF was sustained (>1 minute). Atrial refractory periods were recorded at each pressure. Increased atrial pressure resulted in a reduction in atrial refractory period and a propensity for induction of sustained AF. Higher pressures were needed to induce and sustain AF in the fish oil group compared with the sunflower oil and control groups. The stretch-induced drop in refractory period was also less marked in the fish oil group. Red blood cell, atrial, and ventricular omega-3 fatty acid levels were significantly higher in the fish oil group. The ratio of atrial n-6/n-3 polyunsaturated fatty acids was 13 +/- 0.9 with sunflower oil and 1.5 +/- 0.01 with fish oil (P < 0.001). Conclusions: Incorporation of dietary omega-3 fatty acids into atrial tissue reduces stretch-induced susceptibility to AF.

(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-6, October 2005).

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