Association of left ventricular outflow tract size with arch morphology in interrupted aortic arch

Abstract

Objectives Left ventricular outflow tract obstruction (LVOTO) is a major cause of morbidity and mortality in infants with interrupted aortic arch (IAA). LVOT development may be flow-mediated, thus IAA morphology may influence LVOT diameter and subsequent reintervention. We investigated the association of IAA morphology (type and presence of aortic arch aberrancy) with LVOT diameter and reintervention. Methods All surgical patients with IAA (2001-2022) were reviewed at a single institution. We compared IAA-A versus IAA-B; IAA with aortic arch aberrancy (AAb) versus none; IAA-B with aberrant subclavian artery (AAbS) versus Others. Primary outcomes included LVOT diameter (mm), LVOTO at discharge (≥50mmHg), and LVOT reintervention. Results Seventy-seven infants (mean age 10±19 days) were followed for 7.6 (5.5-9.7) years. Perioperative mortality was 3.9% (3/77) and long-term mortality was 5.2% (4/77). Out of 51 IAA-B (66%) and 22 IAA-A (31%) patients, 30% (n = 22) had AAb. Smaller LVOT diameter was associated with IAA-B [IAA-A: 5.40 (4.68-5.80), IAA-B: 4.60 (3.92-5.50), p = 0.007], AAb [AAb: 4.00 (3.70-5.04) vs None: 5.15 (4.30-5.68) p = 0.006], and combined IAA-B+AAbS [IAA-B+AAbS: 4.00 (3.70-5.02) vs Other: 5.00 (4.30-5.68), p = 0.002]. The likelihood of LVOTO was higher among AAb (N = 6 (25%) vs N = 1 (2%), p = 0.004) and IAA-B+AAbS (N = 1 (2%) vs N = 6 (30%), p = 0.002). Time-to-event analysis showed a signal towards increased LVOT reintervention in IAA-B+AAbS (p = 0.11). Conclusion IAA-B and AAb are associated with small LVOT diameter and early LVOTO, especially in combination. This may reflect lower flow in the proximal arch during development. Most reinterventions occur in IAA-B+AAbS, hence these patients should be carefully considered for LVOT intervention at the time of initial repair.