Background/Purpose: Ankylosing spondylitis (AS) is associated with elevated risk of cardiovascular disease (CVD) and increased mortality. Arterial stiffness is associated with atherosclerosis and CV events. Stiffness can be examined by ultrasound providing β stiffness index and by a more recently developed method, 2 dimensional (D) strain by speckle tracking technique, which measures deformation in more dimensions. The aims were to examine bilateral common carotid arterial (CCA) circumferential 2D strain and β stiffness index and in patients with AS and 1) compare the results with age and sex-matched controls and 2) explore relationships between circumferential strain and β stiffness index with disease related and traditional risk factors for CVD in AS patients.

Methods: A cohort of 149 patients with AS from northern Sweden, mean age 55.3±11.2 years, 102(68.5%) men, 146(98%) HLAB27) were examined with radiographs for modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), BASMI, BASFI, ASDAS-CRP, BASDAI and conventional risk factors of CVD. Circumferential 2D strain and β stiffness index were assessed of bilateral CCAs. Forty-six AS patients and 46 age- and sex-matched controls without hypertension, diabetes or history of myocardial infarction or stroke were compared. Univariate and standard multivariable linear regression analyses were used. Variables with a univariate p-value ≤ 0.1 were considered for the multivariable models.

Results: The 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 the mean bilateral β stiffness index was higher, 13.1±1.6 mmHg/mm vs 12.3±1.3 mmHg/mm, p=0.018. Multivariable linear regression analyses with mean circumferential bilateral 2D strain as dependent variable showed inverse significant associations with age, erythrocyte sedimentation rate, history of anterior uveitis and to be on a csDMARD and/or a bDMARD (R2 0.33) while mean β stiffness index as dependent variable showed significant associations with age (R2 0.22).

Conclusion: Both CCAs 2D strain and β stiffness index differed significantly between AS patients and controls indicating worse subclinical arterial status in AS. The circumferential 2D strain was associated with age and AS related variables while the β stiffness index with age indicating that the methods complement each other. Longitudinal studies are required to investigate the clinical importance of these CV surrogate biomarkers in AS.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/arterial-elasticity-by-2-dimensional-circumferential-strain-and-beta-stiffness-index-in-patients-with-ankylosing-spondylitis/