Cardiac
L-carnitine content, essential for mitochondrial
fatty acid transport and
ATP-
ADP exchange, decreases during
ischemia. In animal models, administration of the natural derivative,
L-propionylcarnitine, may reduce
ischemia and improve cardiac function. To evaluate possible antiischemic effects of
L-propionylcarnitine was compared with placebo in a randomized, double-blind, parallel design, in addition to preexisting
therapy. Patients with > or = 2 anginal attacks per week and objective signs of
ischemia with angina during bicycle exercise testing were included. After an initial 2-week, single-blind placebo phase, 37 patients received 500 mg
L-propionylcarnitine tid, and 37 patients received placebo for 6 weeks. Both groups were comparable at baseline. Three patients discontinued the study while on placebo (two because of noncompliance, one because of palpitations) and one while on
L-propionylcarnitine (noncompliance). Although heart rate, blood pressure at rest, and maximal exercise were not affected,
L-propionylcarnitine increased the time to 0.1 mV ST-segment depression [44 +/- 3 vs. 8 +/- 2 seconds (mean +/- SEM) in the placebo group; p = 0.05], and exercise duration improved by 5% compared with placebo. Anginal attacks and the consumption of
nitroglycerin were not affected in either group. Thus, following a 6 week treatment period,
L-propionylcarnitine induced additional, albeit marginal, antiischemic effects in anginal patients who were still symptomatic despite maximal conventional antianginal
therapy. It is questionable whether in these patients this form of metabolic treatment will achieve great benefit, although in some improvement can be expected.