Distal ascending aortic dilatation portends a near 2-fold greater risk of cardiovascular mortality than proximal enlargement: results from 120,000 patients in a nationwide echocardiographic database
Authors: Nadel J , Paratz E , Humphries J , Suinesiaputra A , Young A , Botnar R , Celermajer D , Strange G , Playford D 
Published: October 2024

Abstract

Background
The management of thoracic aortic dilatation is clinically challenging and acute aortic dissection (AD) is under-recognised as a primary cause of death. Despite the majority of AD occurring in non-severely dilated aortas, absolute aortic diameter remains the most utilised criterion for adjudging preventative surgical correction. In order to improve outcomes and guide management, greater prognostic understanding is needed.

Purpose
We examined a nationwide echocardiographic dataset linked to mortality outcomes to determine how ascending thoracic aortic dilatation and its site affects cardiovascular disease (CVD) mortality over time.

Methods
The National Echocardiography Database Australia (NEDA) was examined for aortic dimensions at the sinuses of Valsalva (SoV), sinotubular junction (STJ) and ascending aorta (AscAo) in patients who had undertaken &gt;1 echocardiographic study. Following separation of those who had undergone corrective aortic surgery, patients were stratified according to absolute aortic diameters and grouped as normal (&lt;4cm), mild (4.0-4.5cm), moderate (4.5-5cm) and severely (&gt;5cm) dilated at the prescribed thoracic aortic sites. Mortality data was then linked from the National Death Index (NDI).

Results
398,905 echocardiographs from 121,115 patients with a mean age of 62.6±16.2 years were included. At the time of mortality data linkage, 38,681 (32%) had died, of whom 13,292 (34%) died from CVD causes and only 276 (0.007%) had aortic dissection recorded as their primary cause of death. Severe aortic dilatation at any site increased the likelihood of 10-year CVD mortality (29% vs. 15% in those with normal diameters; HR 3.00; CI 1.60-5.63; p&lt;0.0001), with an incremental increase in the probability of CVD death when moving from the proximal to distal ascending aorta; 10-year CVD mortality at the SoV 26% (HR 1.93; CI 1.29-2.87; p&lt;0.001), STJ 39% (HR 2.82; CI 1.64-4.86; p&lt;0.001) and AscAo 44% (HR 4.74; CI 2.46-9.13; p&lt;0.001) respectively (Figure 1). When examining those patients who had undergone corrective aortic surgery, the likelihood of 10-year CVD mortality was comparable to the population with normal aortic diameters (17 vs. 15%, HR 1.1; CI 0.9-1.36; p=0.3) (Figure 2).

Conclusion
Severe aortic dilatation increases the probability of 10-year cardiovascular mortality. Interestingly, there is an incremental increase in the likelihood of CVD mortality when moving from the proximal to distal ascending aorta, with severe AscAo dilatation conferring a near 2-fold greater risk of CVD mortality compared with severe SoV aneurysms. Additionally, surgical aortic intervention nearly normalises survival probability to the population with healthy aortic diameters. These results identify new considerations for prognostication, risk stratification and surgical guidance of aortic repair.CVD mortality by aortic dilatationCVD mortality after aortic intervention