Abdominal aortic aneurysm growth profiles over time: Prognostic implications and biological insights.

Abstract

Progressing abdominal aortic aneurysms (AAAs) show a patchwork of rupture-prone wall segments with fast growth and/or greater wall stress, often not located around the maximum diameter. This study aimed to characterize AAA growth profiles over time and investigate their prognostic value for AAA progression. In this prospective, observational cohort of AAA patients (maximum diameter, ≥40 mm) under periodic surveillance, participants underwent blood sampling at baseline and were followed over 2 years with annual computed tomography imaging. Aortic diameter was measured repeatedly between the lowermost renal artery and 10 mm above the aortic bifurcation at 5% length intervals. The greatest diameter change (≥2.6 mm or <2.6 mm) and its distance from the maximum aneurysm diameter (>10% or ≤10% of aneurysm length) were used to classify patients at 1 and 2 years into slow, edge, and peak growth. A symmetry test was used to test for directionality of changes in growth profiles between the first and the second year. Secondary outcomes were time to surgical threshold, as well as differences in diameter and volume growth and circulating biomarkers, investigated using Cox, mixed-effects, and linear regression models, respectively. Of 101 patients, 92 adhered to 1-year imaging recommendations (mean age, 72 ± 6.9 years; 84 males; median maximum diameter, 45 mm; 25th-75th percentile, 42-48 mm). Fifty-five patients showed edge growth, 20 slow growth, and 17 peak growth. At 2 years, 75 of 76 alive, untreated patients underwent imaging; 41 showed edge growth, 12 slow growth, and 22 peak growth. Most patients did not change in growth profile over time. Those who did change went from slow to edge to peak growth (P = .027). The cumulative incidence to qualify for surgery in the subsequent year was 0% (95% confidence interval [CI], 0-0) for patients with slow growth, 23% (95% CI, 12%-36%) for edge growth, and 43% (95% CI, 16%-67%) for peak growth (slow vs edge, P = .029; edge vs peak, P = .186). When accounting for differences in maximum diameter, the hazard ratio for qualifying for surgery was 5.24 (95% CI, 1.68-16.38) for patients showing peak growth, compared with edge growth (P = .004). Fast AAA growth predominantly occurs at the edges of the aneurysm, which may shift toward the maximum diameter over time. These growth profiles, alongside maximum aneurysm diameter, may help to identify patients who are more or less likely to qualify for surgery in the short term.