Background Large studies validated the ankle-brachial index (ABI) as an important clinical marker of peripheral atherosclerosis in general population. However there are few studies regarding ABI in patients with antiphospholipid syndrome (APLS), a clinical condition associated with an increased cardiovascular risk.
Objectives The aim of this study was to evaluate the predictors of an abnormal ABI in patients with APLS.
Methods In 106 patients with APLS (primary and secondary) we performed the evaluation of the ABI according to standard recommendations. Traditional cardiovascular risk factors, along with a large spectrum of antiphospholipid antibodies (including the antiphosphatidylserine, antiphosphatidylethanolamine and antiprothrombine antibodies) and lupus anticoagulant were assessed. We calculated the pulse pressure as the difference between systolic and diastolic blood pressure – as a marker of arterial stiffness. We divided the study group in two subgroups: A- patients with an abnormal ABI (defined by a value below 0.9); and B - patients with normal ABI.
Results In our study, 30 pts (28.3%) were found to have a low ABI. Mean age (51.1±13.2 in subgroup A vs 42.1±11.0 yo in subgroup B, p=0.001), mean age at diagnostic (42.9±13.4 vs 36.1±10.6 yo, p=0.007), prevalence of arterial hypertension (63.3 vs 32.8%, p=0.008), diabetes (23.3 vs 6.5%, p=0.02), pulse pressure (53.8±12.3 vs 48.6±9.8 mmHg, p=0.02), fasting glucose (95.2±17.5 vs 84.6±15.9 mg/dl, p=0.004) and values of HDL-cholesterol in men (43.1±7.9 vs 58.4±10.1, p=0.01) were associated with an abnormal ABI. Anti-beta 2-glycoprotein I IgG antibodies [median values (interval): 4.00 (1.00-79.00) vs 3.00 (0.00-29.00), p=0.02] and anti-prothrombin IgM antibodies [4.50 (0.00-82.00) vs 3.00 (0.00-14.00), p=0.05] were found to have higher values in patients with abnormal ABI. The anti-beta 2-glycoprotein IgG antibodies has had the higher AUC (area under the curve) for the prediction of low ABI (AUC=0.660). In multivariate analysis, only the titer of anti-beta 2-glycoprotein I IgG were significantly associated with an abnormal ABI (p=0.04).
Conclusions In our study group of APLS patients we found a high prevalence of an abnormal ABI. As expected, the traditional cardiovascular risk factors are associated with more important vascular changes in these patients. However, only the titer of anti-beta 2-glycoprotein I IgG was independently associated with a low ABI in patients with APLS reflecting the role of disease itself in the pathogenesis of atherosclerosis.
Disclosure of Interest : None declared