Marine polyunsaturated fatty acids in heart failure. Are the theoretical benefits matched by the clinical data?

Chronic heart failure (CHF) is a common condition, which despite major advances, is still characterized by high mortality (with sudden arrhythmic death a particular risk), poor quality of life due to exercise intolerance and frequent hospitalizations. Epidemiological studies suggest that populations with a high intake of marine polyunsaturated fatty acids (PUFAs or fish oils) have low levels of cardiovascular mortality. Animal and human studies of fish oil supplementation have demonstrated improved endothelial function and myocardial relaxation, reduced vascular tone and platelet aggregability, and a stabilization of myocyte excitability by prolongation of the refractory period. Marine PUFAs also have potentially important immune-modulating effects, reducing cytokine production and release, and altering prostaglandin metabolism. Data from patients following acute myocardial infarction have suggested that marine PUFA supplementation may reduce early mortality, mostly by reducing the risk of sudden arrhythmic death. Until recently, data in patients with chronic heart failure was lacking, but the recent publication of the GISSI-HF study, randomizing more than 7000 CHF patients to marine PUFA supplementation or placebo has clarified somewhat the role of these agents. The aim of this article is to review the theoretical benefits of marine PUFAs and to discuss the implications of the GISSI-HF study for the management of patients with CHF.