# Combining Ascending Aortic Diameter and Length and Their Growth Rates Improves the Prediction of Type A Aortic Dissection

## TL;DR

Combining aortic diameter, length, and their growth rates improves prediction of aortic dissection risk beyond current thresholds.

## Contribution

A new risk function using diameter, length, and growth rates improves ATAAD prediction beyond existing preventive surgery thresholds.

## Key findings

- Almost half of ATAAD patients had dimensions below current preventive surgery thresholds.
- A risk function using diameter, length, and growth rates achieved an AUC of 0.83 for 5-year ATAAD prediction.
- Including growth rates in addition to dimensions provides better risk assessment for ATAAD.

## Abstract

The majority of acute type A aortic dissections (ATAADs) occur at ascending aortic dimensions and growth rates below current preventive surgery thresholds. This study aimed to investigate the risk of ATAAD based on the ascending aortic diameter, length, and their growth rates.

The ascending aortic diameters and lengths were measured using repeated pre-dissection computed tomography and magnetic resonance imaging acquired during follow-up to evaluate their growth patterns and rates prior to the ATAAD onset. Measurements and growth rates were used to develop the risk function for the ATAAD risk assessment.

Ascending aortic aneurysm patients (n = 116) were divided into ATAAD (n = 30) and non-ATAAD groups (n = 86). Almost half of the ATAAD patients (46.7%) did not exceed the current preventive surgery thresholds based on the dimensions. A diameter growth rate of 3 mm/year was extremely rare (2.6%). The risk function was introduced in this study, and it could be used to predict the 5-year risk of ATAAD with excellent confidence (area under the curve [AUC] value of 0.83 (95% CI [0.54-0.98])).

The combination of ascending aortic diameter and length and their growth rates offers a valuable tool for assessing the risk of an ATAAD. Almost half of the ATAAD patients fall below the established thresholds when assessed using only ascending aortic dimensions. These findings suggest that preventive surgery thresholds may benefit from including all four parameters: ascending aortic diameter and length and their growth rates.

DilAo-Trial ClinicalTrials.gov ID 5063566

Ascending thoracic aortic aneurysm (ATAA) has been determined to be one of the main risk factors for acute type A aortic dissection (ATAAD).