Pro- and antiarrhythmic properties of a diet rich in fish oil.

Increased consumption of fish rich in omega-3 polyunsaturated fatty acids (omega3-PUFAs) is associated with decreased incidence of sudden cardiac death in post-myocardial infarction patients, but is also related to increased incidence of sudden death and arrhythmias in patients with acute myocardial ischemia. This review discusses the possible pro- and antiarrhythmic mechanisms of omega3-PUFAs in relation to various cardiac pathologies. Differences between circulating and incorporated omega3-PUFAs with respect to electrophysiology are emphasized. We conclude that omega3-PUFAs alter cardiac electrophysiology and thereby may be pro- or antiarrhythmic, dependent on the mechanism of arrhythmia. As omega3-PUFAs may be antiarrhythmic under conditions that favour triggered activity, they may facilitate re-entrant arrhythmias. This may explain the contradictory outcomes of increased intake of fish oil on sudden death and arrhythmias in clinical trials. Advice to increase intake of omega3-PUFA supplements or fatty fish should be tailored to individual patients with respect to the arrhythmogenic mechanisms associated with the underlying pathology.