Elevated plasma fatty acid concentrations prolong cardiac repolarization in healthy subjects

Background: High fatty acid concentrations have been shown to stimulate sympathetic nervous system activity, which may modify ventricular repolarization and thus the Q-T interval on electrocardiogram recordings. Objective: The aim of this study was to investigate whether acute elevations of plasma fatty acid concentrations influence the corrected Q-T interval (Q-Tc), Q-Tc dispersion, and sympathetic nervous system activity in healthy nonobese subjects. Design: Thirty-two healthy subjects ((x) over bar +/- SD: 48 +/- 7 y of age) received an infusion of 10% triacylglycerol emulsion plus heparin (a bolus of 200 U followed by 0.2 U min(-1). kg body wt(-1) for 180 min); on another occasion and in random order, the same subjects received a saline infusion. Results: Compared with the saline infusion, infusion of 10% triacylglycerol emulsion increased plasma fatty acids (P < 0.001) and was associated with an increase in mean blood pressure (P < 0.05), heart rate (P < 0.05), Q-Tc (P < 0.01), Q-Tc dispersion (P < 0.01), and plasma epinephrine (P < 0.005). Further more, individual changes in plasma epinephrine correlated with changes in Q-Tc (r = 0.60, P < 0.001) and Q-Tc dispersion (r = 0.53, P < 0.02) even after adjustment for age, sex, and body mass index (P < 0.03 for all correlations). Only changes in plasma fatty acids (P = 0.04) and plasma epinephrine (P = 0.006) concentrations were significantly and independently associated with the lengthening of the Q-T interval. Conclusion: Our study showed that elevated plasma fatty acid concentrations might affect cardiac repolarization, at least in part because of an increase in plasma catecholamines.