CARNITINE-RELATED ALTERATIONS IN PATIENTS WITH INTERMITTENT CLAUDICATION

Background Carnitine metabolism is altered in peripheral arterial dise ase. L-carnitine supplementation may correct these alterations and imp rove walking performance. Methods and Results Plasma levels of carniti ne and its esters were measured at rest and after maximally tolerated exercise in 22 claudicant patients and 8 normal subjects. One week lat er, this protocol was repeated in patients after random administration of placebo or L-carnitine (500 mg IV as a single bolus). Two groups o f patients emerged. In 10 patients (group IC1), the plasma level of ac etylcarnitine at rest was 3.7+/-0.2 mu mol/L and increased significant ly (P<.01) at maximally tolerated exercise. In 12 patients (group IC2) , the resting level of plasma acetylcarnitine was elevated (7.9+/-0.7 mu mol/L, P<.01) and decreased with exercise. Furthermore, group IC2 p atients had a significantly lower walking capacity than group IC1 pati ents. In both groups, placebo did not affect the metabolic profile, no r did it improve exercise performance. Conversely, after L-carnitine a dministration, all but one patient in group IC2 (n=7) showed an increa se in plasma acetylcarnitine concentration during exercise versus the decrease observed without L-carnitine. This metabolic effect was accom panied by a significant increase (P<.01) in walking capacity. Interest ingly, in group IC1 patients (n=5), L-carnitine neither improved walki ng capacity nor modified the metabolic profile. Statistical analysis s howed that changes in walking capacity with L-carnitine treatment were influenced exclusively by exercise-induced changes in plasma acetylca rnitine. Conclusions In patients with intermittent claudication, asses sment of plasma acetylcarnitine at rest and after exercise may be a me ans to select a target population for L-carnitine therapy.