Exploring the feasibility of the aorta to pulmonary artery ratio as novel risk marker of acute aortic syndromes in dilated aorta without conventional criteria for surgery

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Based on current guidelines, surgery indication of thoracic ascending aortic aneurysm (TAAA) is mainly driven by the aortic diameter. However, most cases of TAAA acute complications occur in patients who did not previously meet the 55 mm criteria for preventive surgical replacement (1). Both aorta indexed to height and to body surface area have been proposed as possible solution but indexed diameters of healthy aortas widely vary (2). Accordingly, new individualized biomarkers to improve the risk stratification of dilated aorta without a conventional criteria for surgery remain an unmet clinical need. Since aorta and pulmonary artery have an established ratio in general population (upper normal ratio of 1.2) (3), the aorta-to-pulmonary-artery ratio (A:PA) may better define the wall stress in a dilated aorta, overcoming the individual limitations of conventional size criteria. Purpose The aim of our study is to find a novel aortic indexed diameter with better prognostic performance. Therefore, we aimed to explore the feasibility of using the A:PA as risk predictor in TAAA with aortic diameter < 55 mm. Methods All consecutive patients with an acute aortic syndrome (AAS), diagnosed by CT scan in our tertiary hospital between January 2010 and June 2021 undergoing surgical repair, were retrospectively analyzed. Patients with pulmonary hypertension were excluded to prevent distortions in the pulmonary artery diameter. Basic clinical characteristics regarding indications of surgery were collected along with measurements of the aortic maximum diameter and pulmonary artery maximum diameter, obtained by multiplane reconstruction (Figure, Panels A, B). Patients were categorized into three groups based on aortic diameter terciles: group A included patients with < 47 mm, group B ≥ 47 mm but < 55 mm and group C ≥ 55 mm. Considering a high risk of concomitant confounding factors the lower tercile was subsequently excluded of the analysis. Results A total 48 patients were included. 69% of the patients had an aortic diameter that would have not fulfilled a preventive surgery indication. Two patients had bicuspid aortic valve, both of them with aortic aneurysms > 55 mm. None had high risk connective tissue disorders. There were no significant differences in baseline characteristics between the groups (Table 1). A PA ratio was similar in group B and C [1.91 (0.41) versus 2.11(0.45); p = 0.251], suggesting a similar aortic wall stress between aortas despite the difference in aortic diameters [49.5 mm (5.0) versus 58 mm (4.7); p < 0.001] (Figure 1, Panels C, D). Conclusions: Our findings suggest that the A PA ratio may be a promising risk stratification biomarker for TAAA without a conventional criteria for preventive surgery. This novel parameter should be prospectively tested in cohorts of TAAA. To the best of our knowledge, this is the first attempt to describe the usefulness of this parameter. Abstract FIGURE 1 Abstract TABLE 1