[Effect of L-carnitine in patients with ischemic heart disease]

To assess the protective effects of L-carnitine (LC) infusion on ischemic heart disease, 30 patients who had angina and ischemic ECG changes during exercise were evaluated by bicycle ergometry. They were categorized in LC and non-treatment (NT) groups. There were no significant differences in age and sex between the 2 groups. Before exercise, 15 patients (9 males and 6 females) received 60 mg/kg LC and the results including hemodynamics, coronary circulation, and cardiac metabolism at rest and during exercise were compared with those of the NT group studied in the same protocol (50 watts x to cycle, 15 min). At the end of 30 min LC drip infusion, the arterial carnitine content (LC (a)) reached 1,980 +/- 257.3 microM and then was maintained at 1,212.7 +/- 136.2 microM during exercise. There was no correlation of LC (a) with the coronary arterio-venous difference nor with myocardial uptake of LC. Although there was no significant difference in coronary blood flow (CBF: mliters/100 g/min) between the LC and NT groups at rest (LC: 92.1 +/- 29.0 vs NT: 88.0 +/- 26.5), CBF during exercise increased significantly in the LC group compared with the NT group (LC: 230.4 +/- 113.8 vs NT: 139.1 +/- 52.7; p < 0.05). In the NT group, there was no significant change in coronary arterio-venous oxygen difference ((a-cs) O2: vol %) during exercise, but in the LC group (a-cs) O2 increased significantly from 10.2 +/- 1.3 to 11.5 +/- 1.9 (p < 0.01). Furthermore, although there was no significant difference in myocardial oxygen consumption (MVO2: mliters/100 g/min) at rest between the 2 groups (LC: 9.30 +/- 2.96 vs NT: 9.71 +/- 3.09), it increased significantly in the LC group compared with the NT group during exercise (LC: 25.11 +/- 9.98 vs NT: 15.55 +/- 6.09). MVO2/LVWI (LVWI = left ventricular work index) and MVO2MT (MT = myocardial tension) did not significantly differ at rest between the 2 groups. However, these 2 indices decreased significantly during exercise (p < 0.05) in the NT group, and remained unchanged in the LC group, showing a significant difference between the 2 groups (both p < 0.05). In myocardial energy substrates, the myocardial uptake ((a-cs) x CBF) of free fatty acid (FFA: muEq/100 g/min) increased significantly in the LC group compared with that of the NT group (LC: 10.16 +/- 13.26-->31.88 +/- 27.58* vs NT: 16.02 +/- 27.92-->18.11 +/- 31.00;* = p < 0.05, LC vs NT).