Association of Regional Wall Shear Stress and Progressive Ascending Aorta Dilation in Bicuspid Aortic Valve

OBJECTIVES The aim of this study was to evaluate the role of wall shear stress (WSS) as a predictor of ascending aorta (AAo) growth at 5 years or greater follow-up. BACKGROUND Aortic 4-dimensional flow cardiac magnetic resonance (CMR) can quantify regions exposed to high WSS, a known stimulus for arterial wall dysfunction. However, its association with longitudinal changes in aortic dilation in patients with bicuspid aortic valve (BAV) is unknown. METHODS This retrospective study identified 72 patients with BAV (age 45 +/- 12 years) who underwent CMR for surveillance of aortic dilation at baseline and $5 years of follow-up. Four-dimensional flow CMR analysis included the calculation of WSS heat maps to compare regional WSS in individual patients with population averages of healthy age and sex-matched subjects (database of 136 controls). The relative areas of the AAo and aorta (in %) exposed to elevated WSS (outside the 95% CI of healthy population averages) were quantified. RESULTS At a median follow-up duration of 6.0 years, the mean AAo growth rate was 0.24 +/- 0.20 mm/y. The fraction of the AAo exposed to elevated WSS at baseline was increased for patients with higher growth rates ( 0.24 mm/y (19.9% [IQR: 10.2%-25.5%] vs 5.7% [IQR: 1.5%-21.3%]; P = 0.008). Larger areas of elevated WSS in the AAo and entire aorta were associated with higher rates of AAo dilation 0.24 mm/y (odds ratio: 1.51; 95% CI: 1.05-2.17; P = 0.026 and odds ratio: 1.70; 95% CI: 1.01-3.15; P = 0.046, respectively). CONCLUSIONS The area of elevated AAo WSS as assessed by 4-dimensional flow CMR identified BAV patients with higher rates of aortic dilation and thus might determine which patients require closer follow-up. (J Am Coll Cardiol Img 2022;15:33-42) (c) 2022 by the American College of Cardiology Foundation.

Automated summary

This study evaluated the predictive role of wall shear stress (WSS) in the growth of the ascending aorta (AAo). It found that higher rates of AAo dilation were associated with larger areas of elevated WSS in patients with bicuspid aortic valve (BAV), suggesting that measuring WSS can help identify BAV patients who require closer follow-up.