Sudden cardiac death: the lost fatty acid hypothesis.

Evidence that an excess of plasma free fatty acids (FFA) might lead to primary ventricular fibrillation and sudden cardiac death has hardened over the 36 years since the hypothesis was proposed. When the sympathetic nervous system is stimulated during the onset of an acute coronary syndrome, catecholamine-induced tissue lipolysis occurs, with a surge of plasma FFA. This may overload the acutely ischaemic myocardium and impair glucose utilization. Myocardial oxygen consumption can increase in regional areas of ischaemia, and could lead to abnormal electrophysiological conduction and refractoriness, with irreversible ventricular arrhythmias. Efforts to combat the adverse effects of excess FFA include beta-blockade, increasing glucose availability and extraction, or inhibition of lipolysis. This last approach appears promising, but no method has yet been clearly shown to prevent primary ventricular fibrillation or sudden cardiac death. The hypothesis remains viable. More research is needed to derive treatment that can be applied as soon as the onset of acute myocardial ischaemia is suspected.