Large Artery Dysfunction in Primary Antiphospholipid Syndrome

The aim of this study was to assess the arterial distensibility of large vessels and changes in microvasculature in primary antiphospholipid syndrome.

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.

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).

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.