Influence of High Plasma Concentrations of Free Fatty Acids on Heart Rhythm in Healthy Fasting Men

Ten healthy male student in regular sinus rhythm fasted for 66 hours. Their overnight fasting plasma concentration of free fatty acids (FFA) was 455 +/- 104 micro mol/1 (mean +/- S.E.M., n=7), the reference value of our laboratory, measured in another normal population of young men, being 344 +/- 28 micro mol/1 (n=10). After 42 and 66 hours of fasting, the plasma concentration of FFA rose to 1198 +/- 181 (p less than 0.01, n=10) and 1471 +/- 89 micro mol/1 (p less than 0.001, n=10), respectively. During the last 24 hours of fasting, the heart rate rhythm was monitored continuously by means of a Holter recorder and computer. No arrhythmias were observed, indicating that elevated plasma concentrations of FFA, exceeding those reported in patients with acute myocardial infarction, are well tolerated by the healthy human myocardium.