Omega-3 fatty acid supplementation

Free fatty acids and the risk of sudden death • Elevated circulating free fatty acids have been reported to be a risk factor for sudden death. In the Paris Prospective Study reported by Jouven et al. [ 3 ], 5250 men were observed over a mean follow-up period of 22 years. The concept that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) may have potential health benefits has been supported by early observations in populations with a high fish intake. Greenland Eskimos, Alaska Natives, and Japanese in fishing villages eat a diet high in fish and have a low incidence of cardiovascular disease. Since these early observations, favorable effects from n-3 PUFAs have been reported for triglyceride reduction, mild hypertension, coronary heart disease prevention, arrhythmias (ventricular arrhythmias, premature ventricular contractions, and atrial fibrillation [AF]), overall mortality, and sudden death mortality. Although variable efficacy has been reported for some of these areas, the data supporting beneficial effects on arrhythmias, particularly ischemic ventricular arrhythmias and sudden death prevention, are perhaps the most compelling. The aim of this review is to survey the data on n-3 PUFAs’ effects on preventing cardiac arrhythmias, specifically sudden cardiac death and ischemic ventricular arrhythmias, premature ventricular complexes (PVCs), and AF. OMEGA-3 VERSUS OMEGA-6 FATTY ACIDS The two main classes of essential fatty acids are omega6 (n-6) and n-3 PUFAs ( Fig. 1 ). The n-6 PUFAs have a double-bond six carbons from the amino terminus, whereas the n-3 PUFAs have a double-bond three carbons from the amino terminus. These fatty acids are essential in that they are not manufactured de novo but must be taken in by diet. The n-6 PUFAs are derived from certain oils and meats. n-6 PUFA linoleic acid is metabolized to γ -linolenic acid and arachidonic acid, which is also derived from meat sources. These are metabolized to n-6–derived eicosanoids, such as thromboxane A 2 , leukotriene B 4 , and prostaglandins, which are considered proaggregatory, proinfl ammatory, and arrhythmogenic. In contrast, the n-3 PUFAs may be derived from certain vegetable oils, which supply α -linolenic acid (ALA). ALA is metabolized to eicosapentaenoic acid (EPA), but with low effi ciency. Our main n-6 PUFA intake is from fi sh and fi sh oils, which supply EPA and docosahexaenoic acid (DHA). These are metabolized to n-3–derived eicosanoids, including prostacyclin, thromboxane A 3 , and leukotriene B 5 , which are considered anti-infl ammatory and antithrombotic [ 1 , 2 ]. Omega-3 Fatty Acid Supplementation for the Prevention of Arrhythmias Mina K. Chung, MD