Effect of a single IV administration of L-propionylcarnitine on myocardial microcirculation assessed by coronary flow velocity reserve measurement in patients with systemic sclerosis: A pilot study

Background: Scleroderma-related cardiac involvement primarily affects coronary microvascular structures and function. The microvasculature disorder is responsible for impairment of coronary flow velocity reserve (CFVR), which has been reported in studies of patients with systemic sclerosis (SSC). L-Propionylcarnitine (L-PC) is a metabolic substance that is associated with a beneficial effect on both microcirculation and myocyte function. Objective: The objective of this study was to determine whether or not CFVR was acutely improved or restored in patients with SSc after a single administration of IV L-PC. Methods: In this pilot study, we screened volunteers with SSc who had no clinical evidence of ischemic heart disease. CFVR was determined by a blinded investigator by evaluating the left anterior descending coronary artery (LADCA) by transthoracic echocardiography during adenosine infusion (140 mu g/kg (.) min(-1) for 5 minutes), 30 minutes before and 15 minutes after administration of L-PC (300 mg IV in 5-minute bolus). Results: Thirty-three patients were screened for this study. Fourteen patients (mean [SD] age, 54.3 [11.2] years; mean [SD] weight, 63.8 [14.5] kg; mean [SD] height, 156.3 [8.7] cm) with SSc and no evidence of coronary heart disease were included in the study; 13 women and I man (4 with the diffuse cutaneous form of SSc and 10 with the limited cutaneous form). After administration of L-PC to patients with SSc, median CFVR was significantly increased from 2.60 to 3.23 (P < 0.001), whereas peak diastolic velocity in the LADCA decreased significantly at the basal evaluation (30.0 vs 26.0, P = 0.009) and significantly increased (80.0 vs 87.5, P = 0.005) during adenosine infusion. No adverse events occurred before, during, or after L-PC infusion. Conclusions: Acute administration of L-PC was associated with a short-term beneficial effect on CFVR in this pilot study of patients with SSc. These results suggest that further, randomized, controlled, double-blind evaluation of longer-term administration to patients with SSc should be considered.