Effects of Sarpogrelate Hydrochloride in Combination with Aspirin on Blood Viscosity and Hemorheological Parameters in Patients with Peripheral and Coronary Artery Disease: A Randomized Controlled Trial

Background/Objectives: Hemorheological abnormalities, including increased blood viscosity and impaired red blood cell (RBC) deformability, contribute to poor vascular outcomes in patients with atherosclerotic diseases. Although sarpogrelate has shown vascular benefits, its additive effect with aspirin on blood viscosity remains unclear. This study aimed to evaluate whether adding sarpogrelate hydrochloride to aspirin improves blood viscosity and hemorheological parameters compared with aspirin monotherapy in patients with peripheral arterial disease (PAD) and coronary artery disease (CAD). Methods: This single-center, randomized, open-label trial evaluated sarpogrelate hydrochloride (300 mg/day) plus aspirin (100 mg/day) versus aspirin monotherapy over 12 weeks in patients with PAD and CAD. Patients were assigned using a computer-generated sequence. The primary analysis used the full analysis set. The primary outcome was change in systolic and diastolic blood viscosity. Secondary outcomes included RBC deformability, aggregation index, critical shear stress, flow-mediated dilation (FMD), metabolic parameters, and quality of life. FMD was performed using standardized protocols with blinded assessment. Results: Sixty-eight patients were randomized (34 per group), of whom 61 were included in the full analysis set (experimental group, n = 31; control group, n = 30). At week 12, systolic blood viscosity remained stable in the experimental group (4.51 → 4.49 cP) but increased in the control group (4.67 → 4.87 cP). The unadjusted mean between-group differences in change from baseline (experimental minus control) were −0.23 cP (95% CI, −0.66 to 0.20) for systolic blood viscosity and −0.55 cP (95% CI, −2.03 to 0.93) for diastolic blood viscosity; the corresponding longitudinal between-group p-values from the MMRM analyses were 0.9481 and 0.9630, respectively. FMD showed no significant between-group difference at week 12 (unadjusted mean difference, −0.60%; 95% CI, −2.05 to 0.85; MMRM p = 0.7727). Patient-reported outcomes (SF-36 and visual analog scale scores) did not differ significantly between groups. Conclusions: In patients with PAD and CAD, no statistically significant additional hemorheological benefit of sarpogrelate combined with aspirin was demonstrated compared with aspirin monotherapy.