Pulmonary arterial hypertension in systemic sclerosis is associated with profound impairment of microvascular endothelium-dependent vasodilatation.

Objective: Impaired microvascular function may contribute to organ complications in patients with systemic sclerosis (SSc). We investigated whether SSc patients with and without pulmonary arterial hypertension (PAH) show a graded impairment of microvascular function compared to healthy controls.

Methods: Twenty-two patients with SSc and 22 controls were studied. All patients underwent right heart catheterization; 6 had no PAH (SSc-nonPAH) and 16 had PAH (SSc-PAH). Acetylcholine (ACh)-mediated endothelium-dependent vasodilatation and sodium nitroprusside (SNP)-mediated endothelium-independent vasodilatation were assessed by iontophoresis combined with laser Doppler flowmetry.

Results: Compared to sex- and age-matched controls, ACh-mediated vasodilatation was reduced in SSc-PAH (340.4% vs 79.5%, respectively; p < 0.01), but not in SSc-nonPAH (340.4% vs 397.9%; p = 0.90). No significant differences were present between the groups in SNP-mediated vasodilatation.

Conclusion: Systemic microvascular endothelium-dependent vasodilatation is markedly reduced in SSc complicated by PAH.