Dietary fats and cardiac arrhythmia in primates

Several epidemiological surveys have suggested that an alteration in the habitual intake of the type rather than the amount of dietary fat may offer a nutritional means for a reduction in mortality from severe cardiac arrhythmia which cannot be achieved at present by the post hoc administration of anti-arrhythmic agents. We have examined this possibility in a series of long-term feeding studies with the small non-human primate marmoset monkey Callithrix jacchus. In both in vitro and in vivo studies of the mechanical performance of cardiac muscle we have found that diets rich in saturated fatty acids promote arrhythmia when the heart is subjected to pharmacological or ischemic stress. Conversely, diets enriched in either omega-6 or omega-3 PUFA are beneficial, reducing the vulnerability to pharmacologically induced dysrhythmia in vitro or ischemic arrhythmia in vivo. In addition, PUFA enriched diets enhance myocardial performance (left ventricular ejection fraction and end diastolic volume) and raise the electrical threshold at which ventricular fibrillation can be induced. These diet-induced changes in cardiac performance are accompanied by significant alterations in the PUFA composition of cardiac muscle membranes, and the subsequent production of myocardial eicosanoids. Both omega-6 and omega-3 PUFA increase the ratio of myocardial prostacyclin:thromboxane, but omega-3 PUFA is more effective as less is required to achieve a significant decrease in pro-arrhythmic thromboxane.(ABSTRACT TRUNCATED AT 250 WORDS)