Prolonged oral L-carnitine substitution increases bicycle ergometer performance in patients with severe, ischemically induced cardiac insufficiency

Acute and chronic L-carnitine application exerts protective effects in a nu mber of cardiac diseases. These favourable effects are attributed to improv ements of the energy metabolism and have been found both in animal experime nts and in man. In order to investigate the effect of long-time oral L-carn itine substitution on physical performance, 41 patients suffering from clas s NYHA II or III cardiac insufficiency were recruited for a clinical study. Following the double-blind, randomized, placebo-controlled design of the s tudy, 20 patients were given 3 x 1g L-carnitine daily for 120 days whereas the control group (21 patients) received placebo. Bicycle ergometer tests w ere used to determine maximum performance, systolic and diastolic blood pre ssure, heart rate, and ST changes. Four series of tests were carried out: o n day 0 (before the first substrate application), on the 60th and the 120th day (during L-carnitine or placebo application), and on the 180th day (60 days after the end of substitution). A significant improvement in performan ce (significantly higher maximum performance during bicycle ergometry) coul d be found within the carnitine group on the 60th and 120th day of L-carnit ine application; and haemodynamical parameters showed a tendency to improve , too. These effects, which were attributed to L-carnitine, could be detect ed even 60 days after the end of substitution. No corresponding changes wer e found in the placebo group. The findings presented in this paper support suggestions of other authors t hat L-carnitine in combination with the usual medication (digitalis, beta-b lockers, calcium antagonists, nitrates) improves performance and effort tol erance in patients with cardiac insufficiency. Moreover, the findings sugge st a favourable long-term effect, which lasts beyond the actual L-carnitine application, on the performance of patients with advanced cardiac insuffic iency.