Microvascular function is impaired in ankylosing spondylitis and improves after tumour necrosis factor α blockade

Ankylosing spondylitis (AS) is associated with increased cardiovascular morbidity and mortality. Microvascular function has been linked to several risk factors for cardiovascular disease. Inflammation in AS may cause microvascular dysfunction. To test this, we assessed microvascular function in (a) patients with AS compared to healthy controls and (b) patients with AS before and after 1 month of anti-tumour necrosis factor (TNF)alpha treatment with etanercept.A total of 15 consecutive patients with AS, who were scheduled for etanercept treatment according to the Assessment in Ankylosing Spondylitis (ASAS) group guidelines, and 12 healthy controls matched for age and sex, were recruited. Endothelium-dependent and independent vasodilatation in skin were evaluated with laser Doppler fluxmetry after iontophoresis of acetylcholine and sodium nitroprusside, respectively. Videomicroscopy was used to measure recruitment of skin capillaries after arterial occlusion.Compared to healthy controls, patients with AS had impaired endothelium-dependent vasodilatation and capillary recruitment. Following anti-TNFalpha treatment, microvascular function improved significantly for endothelium-dependent vasodilatation (p = 0.03) and capillary recruitment (p = 0.006). A significant correlation was observed between changes in endothelium-dependent vasodilatation and changes in erythrocyte sedimentation rate (ESR) (r = -0.56; p = 0.03).Microvascular dysfunction is present in patients with AS with active disease, but improves as inflammation regresses after TNFalpha blockade.