The cardiac antiarrhythmic effects of polyunsaturated fatty acid.

Each year in the United States alone some 250,000 persons die within one hour of an acute myocardial infarction. These deaths are largely due to ischemia-induced ventricular arrhythmias, primarily ventricular fibrillation (VF). Thus a safe, simple means of preventing such arrhythmias has considerable public health benefit potential. We have demonstrated that the intravenous infusion of n-3 polyunsaturated fatty acids (PUFA) from fish oils will prevent ischemia-induced VF in prepared, nonanesthetized, exercising dogs, confirming earlier feeding studies in rats. We show that this protective effect is due to an action of the free acidic form of the PUFA to alter the electrophysiology of individual cardiac myocyte so that the cells are electrically more stable. The electrophysiologic effects, in turn, result from direct and specific effects of the PUFA to block the fast voltage-dependent sodium channels. The binding of the free fatty acids is directly to the protein of the sodium channels and results in prolongation of the inactivated state of these channels. Other ion channels are also affected by the PUFA. Two clinical trials with n-3 PUFA are mentioned which inadvertently support the antiarrhythmic potential of PUFA ingestion.