Should there be a reappraisal of surgical threshold in patients with ascending aortic dilation? Moving beyond aortic diameters

Abstract Background Ascending aortopathy (AA) is mostly asymptomatic and often incidentally diagnosed with a recommendation of surgical aortic replacement once it becomes aneurysmal. However, there is emerging evidence that indexing to height, rather than aortic diameter-based thresholds may better recognize patients who may benefit from earlier surgery. Objective In AA patients not meeting current guideline criteria for aortic surgery, we sought to evaluate the impact of indexing aortic dimensions to height on longer-term outcomes. Methods We included 8,887 patients (mean age 64±13 years, 7056 79% men, 2018 23% with bicuspid aortic valve, 1722 19% hypertensive, 7178 81% betablockers, 4447 50% on calcium channel blockers) with an unrepaired AA (between 4-5 cm), diagnosed on echocardiography between 1/2010 and 12/2023 at our large tertiary referral center. We excluded patients with syndromic aortopathy (n=330), those with an acute aortic dissection/rupture as an initial presentation (n=1179) and aortic repair during follow-up (n=3721). Clinical (including aortic surgery/dissection/rupture during follow-up) data was collected. Maximum AA diameter (cm), ascending aortic height index (AHI, cm/m, 2.43 cm/m considered mildly and 3.21 cm/m severely increased risk) and ascending aortic cross-sectional area to height index (CSAI, cm2/m, ≥10 cm2/m considered increased risk) were calculated. Primary outcome was all-cause mortality. Results Mean AA diameter, AHI and CSAI were 4.4±0.2 cm, 2.5±0.3 cm/m and 8.7±1.4 cm2/m. 5584 (63%) had AHI 2.43 cm/m, 17 (0.2%) had AHI 3.21 cm/m and 1165 (13%) with CSAI ≥10 cm2/m. At a mean follow-up of 5.6±4 years, there were 1058 (11.9%) deaths, 128 (1.4%) aortic dissection and 4 (0.04%) aortic ruptures. Of the deaths, 325 (31%) occurred at AHI 2.43 cm, 1052 (99%) at AHI 3.21 cm/m and 864 (82%) occurred at CSAI10 cm2/m. Similarly, of the dissections 43 (34%) occurred at AHI 2.43 cm, 128 (100%) at AHI 3.21 cm/m and 100 (78%) occurred at CSAI10 cm2/m. All aortic ruptures occurred at AHI3.21 cm/m and CSAI 10 cm2/m. Spline analysis for hazard of mortality using various AA measurements (AA diameter based on sex [Figure A-B, AHI Figure C and CSAI Figure D) demonstrate that hazard ratio for death increase in women with AA diameter 4.5 cm and in all patients at AHI 2.5 cm/m and CSAI at ~ 9 cm2/m. Conclusions In patients with AA not at a guideline threshold for surgery, relying on absolute AA diameters may underestimate higher risk of mortality in women. Indexing aortic dimensions to height (either AHI or CSAI) might identify a group of higher-risk AA patients who do not meet guideline criteria and perhaps might benefit from an earlier aortic surgery.Spline analysis for hazard of mortality