Evaluation of the effect of sildenafil on the microvascular blood flow in patients with systemic sclerosis: a randomised, double-blind, placebo-controlled study.

To evaluate the effect of sildenafil as add-on therapy on the microvascular blood flow in patients with Raynaud's phenomenon (RP) secondary to systemic sclerosis (SSc).In this double-blind, placebo-controlled study, 41 patients with RP secondary to SSc were randomly assigned to receive oral sildenafil 100 mg/day (21 patients, mean age 47.2 years) or placebo (20 patients, mean age 41.6 years) for 8 weeks. Patients were evaluated at baseline, 8 weeks after treatment, and 2 weeks after the end of the treatment. The primary outcome measures were the mean changes in finger blood flow (FBF) measured using laser Doppler imaging before and after cold stimulus at 8 weeks of treatment. Secondary endpoints included frequency and duration of RP attacks, Visual Analog Scale (VAS) score for RP severity, Raynaud's condition score, and serum levels of VEGF and endothelial progenitor cells (EPCs).After 8 weeks of treatment, the sildenafil group presented a significantly higher mean percentage change from baseline in FBF before cold stimulus (p=0.026), and in FBF after cold stimulus (p=0.028) compared with the placebo group. There was a significant improvement in the duration of RP and in the percentage change from baseline to week 8 in the RP VAS score in sildenafil compared with placebo. There were no changes in EPCs and VEGF levels after treatment in either group.Sildenafil improved digital blood flow and RP symptoms in SSc patients after 8 weeks of treatment, and might be a good therapeutic option for secondary RP.