Ultrasound Strain Patterns are Associated with Abdominal Aortic Aneurysm Growth

Objective: Surveillance of abdominal aortic aneurysms (AAAs) traditionally relies on diameter measurements, yet up to 10% of ruptures occur below repair thresholds. The relationship between localised wall strain and future AAA growth remains unexplored. This study aimed to examine localised AAA wall strain patterns and their association with aneurysm growth. Methods: This was a prospective study of patients with an infrarenal AAA under surveillance with conventional ultrasound. In a standard examination, ten second ultrasound videos (cineloops) were acquired in transverse plane with the curved array transducer at the maximum anteroposterior diameter during breath hold. From these cineloops, strain patterns were extracted and analysed via functional data analysis to assess changes over time and associations with annual AAA diameter growth. Results: Two hundred and seventy-eight patients (median age 73 years; 238 men) across 1 117 clinic visits were included, with a median follow up of 2.3 years. Progressive vessel wall stiffening and increasingly homogeneous strain patterns were observed over time (p < .001). Baseline strain patterns were statistically significantly associated with future AAA growth (p = .006), especially in specific regions. In the posterior left and right vessel wall, a 5% point increase in strain corresponded to a 31.9% and 6.7% higher annual growth rate, respectively. Conversely, the same increase at the anterior middle wall was linked to a 33.3% reduction in annual growth rate. These associations remained statistically significant after adjusting for baseline diameter, age, sex, smoking, hypertension, and diabetes (p = .041). Conclusion: Ultrasound strain mapping identified biomechanical regions linked to AAA progression. Strain patterns were associated with future growth independently of diameter, supporting their potential utility in complementing diameter in AAA monitoring and risk stratification.