Rheumatoid arthritis (RA) is characterized by excess cardiovascular risk. Laser Speckle Contrast Imaging (LSCI) is a novel and highly reproducible technique for the real-time evaluation of skin microcirculation. However, relevant data using non-invasive laser techniques remain far too limited in RA, especially in patients free from cardiovascular risk factors with relatively suppressed inflammatory load.
Design and method:
We assessed skin microvascular function in a well-characterized sample of RA patients free from hypertension and cardiovascular diseases with low levels of systemic inflammation, compared to non-RA individuals. Microvascular function was dynamically evaluated using LSCI coupled with a post-occlusive reactive hyperaemia protocol. Applanation tonometry with the Sphygmocor device was applied to assess a) subendocardial viability ratio (SEVR) or Buckberg index as a functional marker of microvascular myocardial perfusion, b) carotid-femoral pulse wave velocity (PWV) as a marker of macrovascular dysfunction.
We studied 35 patients with RA at remission or low disease activity, and 35 controls matched for cardiovascular risk factors. Skin microvascular responses were impaired in RA patients compared to controls, specifically baseline flux [46.8(18.9) vs 36.4(13.9) LSPUs, p < 0.001], occlusion flux [12.4(13.5) vs 7.0(3.6) LSPUs, p = 0.001], time-to-peak [7.0(0.4) vs 11.0(8) sec, p < 0.001], peak magnitude [113.1(25.4) vs 99.1(32.5) LSPUs, p = 0.017], peak-to-baseline magnitude [136.5(75.2) vs 172.1(65.9) %, p = 0.014], baseline cutaneous vascular conductance (CVC) (0.54 ± 0.15 vs 0.44 ± 0.14 LSPUs/mmHg, p = 0.006), and percentage increase in CVC [139.5(75.3) vs 172.1(67.3) %, p = 0.011]. Moreover, SEVR was lower in RA patients compared to controls (140.6 ± 21.8 vs 157.2 ± 25.2%, p = 0.046), whereas PWV did not significantly differ. SEVR strongly and significantly correlated with nearly all LSCI indices (baseline and occlusion flux, peak magnitude, peak-to-baseline magnitude, baseline CVC, and percentage CVC increase). PWV significantly correlated only with baseline flux, occlusion flux, and time-to-peak.
Microcirculation dynamics appear impaired even in RA patients with relatively low inflammatory load, regardless of cardiovascular risk factors. Importantly, we showed for the first time an association between impaired skin microvascular dynamics assessed with LSCI and microvascular myocardial perfusion using SEVR. Further studies need to evaluate the prognostic potential of LSCI in terms of cardiovascular risk in RA.