Large Artery Dysfunction in Primary Antiphospholipid Syndrome

Objective The aim of this study was to assess the arterial distensibility of large vessels and changes in microvasculature in primary antiphospholipid syndrome. Methods Twenty-two antiphospholipid syndrome (APL) patients and 66 age-, sex-, height-, and blood pressure-matched controls were evaluated. Second derivative of the finger photoplethysmogram (SDPTG) was used as a noninvasive method to evaluate the pulse wave. The b/a and d/a indices, which reflect, respectively, large-vessel and small-vessel properties, were calculated from the SDPTG waveform components. Vascular age index was also determined. Results Arterial thrombosis occurred in 59.1% (13/22) of APL patients, with a predominance of stroke episodes (61.5%). Venous thromboembolism was observed in 36.4% (all deep venous thrombosis), and obstetric complications in 36.4%. Frequency of diabetes mellitus, smoking, and dyslipidemia was comparable in APL patients and control subjects (P > 0.05). Concerning plethysmography findings, b/a ratio was higher in patients than in control subjects (-0.44 0.16 vs. -0.54 +/- 0.18, P = 0.034), whereas d/a ratio (-0.30 +/- 0.16 vs. -0.31 +/- 0.18, P = 0.83) was comparable. Moreover, SDPTG (-0.16 +/- 0.35 vs. -0.30 +/- 0.38, P = 0.16) and vascular age index values (53.5 +/- 11.6 vs. 51.8 +/- 16.1, P = 0.65) were alike in both groups. Regarding disease-related factors, patients with arterial and venous thrombosis had similar b/a, d/a, and vascular age indices (P = 0.95; P = 0.06; P = 0.12, respectively). Conclusions The higher b/a ratio in APL patients suggests decreased distensibility of large arteries and may be why APL patients are at higher risk for cardiovascular events. The d/a ratio, that is considered a marker of small vessel vascular resistance, was not different than controls. Further studies are needed to evaluate vascular factors that predispose APL patients to atherosclerotic events.