Saturated, n-3 and n-6 polyunsaturated fatty acids and cardiac arrhythmias

The dietary lipid intake in occidental countries is currently too high and the dietary polyunsaturated fatty acids/saturated fatty acids (P/S) ratio is too low. In rat, a rich saturated fatty acid diet decreased the cardiac performance and increased the ischemic ventricular arrhythmia occurence. Dietary polyunsaturated fatty acids (PUFA) protect the myocardium against ventricular arrhythmias induced either by isoprenaline or by local ischemia. Selective changes in membrane phospholipids induced by dietary n-3 PUFA may be involved in the observed reduction of ischemic damage in the heart. The n-3 PUFA stabilize the electrical activity of isolated cardiac myocytes by a specific modulation of the sarcolemmal voltage-dependent sodium and the L-type calcium currents. This appeared to be the probable major antiarrhythmic mechanism of PUFA. In man, several long-term epidemiological surveys and some direct intervention trials suggest that n-3 PUFA rich diets reduce mortality from coronary artery heart diseases. It seems feasible to modulate the arrhythmic cardiovascular risk factors by decreasing the total amount of dietary fat and increasing the proportion of PUFA.