Effects of chronic omega-3 polyunsaturated fatty acid supplementation on human atrial electrophysiology.

Background: Omega-3 polyunsaturated fatty acids in fish oils may have antifibrillatory effects. Their mechanism of action in humans is poorly understood.

Objective: The purpose of this study was to investigate the effects of chronic fish oil supplementation on human atrial electrophysiology (EP).

Methods: Two groups of patients without clinical AF or structural heart disease and fish intake ≤1/week were prospectively recruited into a control group (n = 30) and a fish oil group (n = 31). The latter were prescribed 6 g/day of fish oil for ≥1 month before an EP study. The following were compared at time of EP study: serum omega-3 levels; right atrial and coronary sinus effective refractory periods (ERPs); interatrial, intra-atrial, left atrial, and coronary sinus conduction at baseline and the maximal conduction delay with the shortest propagated extrastimulus; and inducibility of AF (10 inductions/patient).

Results: The following significant differences were noted favoring the fish oil group at time of EP: (1) twofold higher total omega-3 levels (P < .001); (2) lengthening of ERPs by 8%-14% at all measured sites and pacing cycle lengths (P < .05); (3) no effect on baseline interatrial, intra-atrial, left atrial, and coronary sinus conduction but a significant attenuation of maximal conduction delay (P < .05); (4) less inducible AF (AF ≥30 seconds: 24.2% vs. 7.9%; P < .001); (5) shorter mean duration of induced AF (P = .003); and (6) prolongation of induced AF cycle length (P < .001).

Conclusions: Chronic fish oil supplementation in humans prolongs atrial refractoriness and reduces vulnerability to inducible AF. These EP changes may explain the antifibrillatory effect of chronic fish oil ingestion.