Prognostic value of aortic height and size indices in veterans with ascending aortic aneurysm

Surgical guidelines for ascending thoracic aortic aneurysms are diameter-based despite complications below thresholds. Aortic height index (AHI) and aortic size index (ASI) were added to improve risk assessment but remain unvalidated.

Retrospective cohort study of veterans with dilated ascending aorta or ascending thoracic aortic aneurysms (≥4.0 cm) from 1998 to 2024. Primary outcome was all-cause mortality; secondary outcome was aortic-specific mortality. Patients were stratified into 5 AHI and ASI groups using guideline thresholds with substratification below each threshold. Associations with mortality were evaluated using cause-specific Cox models. Multivariable models were adjusted for age and clinical comorbidities.

There were 764 veterans (median age, 76 years [range, 71-80 years]; 745 [98.0%] men) with ascending thoracic aortic aneurysms diameter of 4.40 cm (range, 4.20-4.70 cm). Ninety-two patients underwent elective repair (5-year cumulative incidence, 10.4%). In unadjusted models, the highest AHI category (≥3.21 cm/m) was associated with higher all-cause mortality compared with AHI <2.35 cm/m (hazard ratio [HR], 8.78; 95% CI, 2.63-29.3; P < .001), as was ASI ≥3.08 cm/m² compared with ASI <1.95 cm/m² (HR, 14.9; 95% CI, 5.52-40.0; P < .001). These associations persisted after multivariable adjustment (AHI: adjusted HR, 4.69; 95% CI, 1.32-16.7; P = .02; ASI: adjusted HR, 8.43; 95% CI, 2.98-23.8; P < .001). For aortic-specific mortality, the highest AHI group was associated with risk in univariable analysis (HR, 9.14; 95% CI, 1.13-74.0; P = .04), whereas ASI showed a borderline association (HR, 8.08; 95% CI, 0.98-40.0; P = .05); neither remained significant after adjustment.

Associations among AHI, ASI, and mortality support their potential role as adjuncts in aortic risk stratification.