Biomechanical Properties of Common Carotid Arteries Assessed by Circumferential 2D Strain and β Stiffness Index in Patients With Ankylosing Spondylitis

Abstract

Objective.Ankylosing spondylitis (AS) is associated with an elevated risk of cardiovascular disease (CVD) related to atherosclerosis, preceded by arterial stiffness. We aimed to examine common carotid artery (CCA) biomechanical properties using ultrasound to calculate β stiffness index (indicating arterial stiffness) and, a more recently developed technique, 2-dimensional (2D) speckle tracking strain (indicating arterial motion and deformation, strain) to (1) compare with age- and sex-matched controls, and (2) analyze relationships between strain and stiffness with disease characteristics and traditional risk factors for CVD in patients with AS.Methods.In this cross-sectional study, a cohort of 149 patients with AS, mean age 55.3 ± 11.2 years, 102 (68.5%) men, and 146 (98%) HLA-B27–positive, were examined. Bilateral CCA were examined for circumferential 2D strain and β stiffness index. A subgroup of 46 patients was compared with 46 age- and sex-matched controls, both groups without hypertensive disease, diabetes, myocardial infarction, or stroke.Results.Mean bilateral circumferential 2D strain was lower in AS patients compared with controls (7.9 ± 2.6% vs 10.3 ± 1.9%, P < 0.001), whereas mean bilateral β stiffness index was higher (13.1 ± 1.7 mmHg/mm vs 12.3 ± 1.3 mmHg/mm, P = 0.02). In multivariable linear regression analyses, strain was associated with age, erythrocyte sedimentation rate, history of anterior uveitis, and treatment with conventional synthetic disease-modifying antirheumatic drugs (DMARD) and/or biological DMARD (R2 0.33), while stiffness was associated with age (R2 0.19).Conclusion.Both CCA circumferential 2D strain and β stiffness index differed between patients with AS and controls. Strain was associated with AS-related factors and age, whereas only age was associated with stiffness, suggesting that the obtained results reflect different pathogenic vascular processes.