Abstract 13304: Intrinsic Morphology Influences the Natural History of Neo-Aortic Root Dilatation and Pathologic Neo-Aortic Regurgitation in Transposition of the Great Arteries

Abstract

Introduction: Neo-aortic root dilatation and pathologic neo-aortic regurgitation (AR) can lead to significant late morbidity after the arterial switch operation (ASO) for dextro-transposition of the great arteries (dTGA). Hypothesis: The natural history of root dilatation in dTGA is influenced by intrinsic morphology. Aims: To i) delineate the natural history of root dilatation in repaired dTGA and ii) to histologically characterize the great arteries in unrepaired dTGA. Methods: A single-center review of patients who underwent the ASO from 07/1981-09/2022 was performed. Morphology was categorized as dTGA with intact ventricular septum (dTGA-IVS), dTGA with ventricular septal defect (dTGA-VSD), and double outlet right ventricle-TGA type (DORV-TGA). Echocardiographically-determined diameters and derived z-scores were measured at the annulus, sinus of Valsalva (SoV), and sinotubular junction (STJ) immediately before the ASO and throughout follow-up. Linear mixed-effects models assessed trends in dimensions over time. We also histologically examined the aortic and pulmonary roots of 10 cases of unrepaired dTGA from our Cardiac Registry. Results: Of 1359 patients meeting entry criteria, 593 (44%) had dTGA-IVS, 666 (49%) had dTGA-VSD, and 100 (7%) had DORV-TGA. At a median follow-up of 8.3 years (range 0.1-39.3 years), 129 (9.5%) patients had ≥moderate AR or required a neo-aortic valve or root reoperation ( Fig-A ). Overall growth of the root is shown in Fig-B . At baseline, there were no differences in annular, SoV, or STJ diameters between dTGA-IVS patients and dTGA-VSD or DORV-TGA patients. At 30 years, DORV-TGA patients had significantly larger diameters at the annulus (p<0.001), SoV (p=0.039), and STJ (p=0.041) relative to dTGA-IVS patients ( Fig-C ). Specimens of the aortic and pulmonary roots from a representative case of unrepaired dTGA are shown in Fig-D . Conclusions: Longitudinal surveillance of the neo-aortic root is warranted long after the ASO.