Abstract 12701: Combined Allometric Normalization of Ascending Aortic Diameter and Assessment of Complication Risk May Support an Earlier Prophylactic Replacement Preventive of Type a Dissection

Abstract

Introduction: Guideline recommendations of prophylactic surgery in ascending aortic dilation by maximum aortic diameter (MAD) fail to predict > 50% of type-A dissections (AD). Assessment of post-dissection diameters as reference and lack of somatometric normalization may preclude an appropriate risk estimation. Hypothesis: The combined assessment of Z-score and Svensson-index (cross-area/height) based on pre-dissection aortic diameters may be advantageous to indicate prophylactic ascending aortic replacement. Such an approach would include information on normalized vascular dilatation together with a clinical aortic risk indicator. Methods: During two years (2018-2019), data from 515 AD-patients were prospectively recorded at 32 tertiary Spanish hospitals (Registro Español Síndrome Aórtico-III). Pre-dissection aortic diameters were estimated based on the in vitro observations made by Williams et al. on the perimeter change of normal human aortas after the creation of a dissection (PMID: 9122399). Svensson indexes were correlated with ascending aorta Z-scores using quadratic regression. Results (Figure): Setting thresholds of increased risk at Svensson-index >10 cm 2 /m and aortic dilation at Z-score >3, 59% of patients had low Svensson and low Z-score category, 19% low Svensson but high Z-score and 22% high Svensson and high Z-score. No patient with Svensson-index <10 cm 2 /m and Z-score either < or > 3 had an indication for surgery according to guidelines. Among patients with Svensson-index >10 cm 2 /m and aortic dilation at Z-score >3, approximately 1/3 (32%) would have a surgical indication whereas 2/3 (68%) would not. Conclusions: According to current guidelines, only one third of high Svensson and high Z group (7% of the total cohort) would deserve elective surgery. More proactive guidelines, suggesting replacement of ascending aorta in patients with Svensson-index >10 and Z-score>3, would spare from dissection 22% of current cases.