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 involve- ment primarily affects coronary microvascular struc- tures and function. The microvasculature disorder is responsible for impairment of coronary flow velocity re- serve (CFVR), which has been reported in studies of pa- tients with systemic sclerosis (SSc). L-Propionylcarnitine (L-PC) is a metabolic substance that is associated with a beneficial effect on both microcirculation and myo- cyte function. Objective: The objective of this study was to deter- mine whether or not CFVR was acutely improved or restored in patients with SSc after a single administra- tion 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 investiga- tor by evaluating the left anterior descending coronary artery (LADCA) by transthoracic echocardiography dur- ing adenosine infusion (140 μg/kg min–1 for 5 min- utes), 30 minutes before and 15 minutes after admini- stration 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 1 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, me- dian 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 evalu- ation (30.0 vs 26.0, P = 0.009) and significantly in- creased (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 as- sociated with a short-term beneficial effect on CFVR in this pilot study of patients with SSc. These results sug- gest that further, randomized, controlled, double-blind evaluation of longer-term administration to patients with SSc should be considered.