Progression of Aortic Dilation in Patients with Tetralogy of Fallot with Pulmonary Atresia and Major Aortopulmonary Collateral Arteries.

Patients with tetralogy of Fallot, pulmonary atresia and major aortopulmonary collateral arteries (TOF/PA/MAPCAs) demonstrate enlarged aortic dimensions. Although aortic z-scores derived from normal populations are widely used, these have limited utility in a population where dilation is nearly universal. The objectives of the study were to determine the range of values of aortic dilation across pediatric patients with TOF/PA/MAPCAs, characterize the trajectory of aortic growth before and after surgical intervention, and report the incidence of important aortic complications at long-term follow-up. We performed a retrospective evaluation of pediatric TOF/PA/MAPCAs patients repaired only at our institution over 20 years (2003-2023). Aortic dimension measurements were performed on up to 3 echocardiograms for each patient: initial echocardiogram (before any intervention), intermediate echocardiogram (< 30 days before complete repair), and post-operative echocardiogram (≥ 1 year following complete repair). Last available echocardiogram was also reviewed. Degree of aortic regurgitation and rates of aortic growth were assessed and compared by surgical strategy. 224 patients were included in the study, 73 (33%) underwent staged repair with a surgical aortopulmonary window and/or bilateral unifocalization to central shunt before eventual complete repair. All aortic dimension z-scores on the initial and intermediate echocardiograms were classified as severely dilated. There was a statistically significant increase in aortic annulus (p = 0.006) and ST junction (p < 0.001) z-scores between the initial and intermediate echocardiograms, with a significant decrease in all aortic dimension z-scores by the post-operative echocardiogram, returning to initial z-score values. Growth rates (mm/year) between the initial and intermediate echocardiograms compared to the intermediate and post-operative echocardiograms were greater for aortic annulus (8.9 ± 12.1 vs. 1.7 ± 3.2, p < 0.001), root (10.6 ± 9.3 vs. 2.3 ± 3.1, p < 0.001), and ST junction (9.1 ± 8.7 vs. 2.0 ± 3.3, p < 0.001), and did not differ by surgical strategy (staged vs. single-stage complete repair). Aortic dimension z-scores continued to significantly decrease at long-term follow-up (median follow-up time 8.5 years [IQR 3.8-13 years]). Only 4 patients in the cohort had more than mild aortic regurgitation at the post-operative echocardiogram (2 moderate, 2 severe), and all 4 patients eventually required surgical intervention on the aortic valve and ascending aorta within the long-term follow-up time frame. Our study demonstrated severely dilated z-scores for all aortic measurements across time, with an increase in growth rates before complete repair and return to initial values over a year following septation with continued decrease at long-term follow-up. These results support that progressive aortic dilation after complete repair does not occur, and despite severe aortic dilation, the incidence of requiring major aortic intervention for patients with TOF/PA/MAPCAs at long-term follow-up remains low. These findings may serve as the foundation for establishing normative reference values specific to this population, and could facilitate the development of new z-score equations that more accurately reflect expected aortic dimensions. Improved characterization of the longitudinal findings in this population better equips us to counsel families, and provides helpful clinical guidance for interval surveillance evaluations.