(CCSP021) ARCH MORPHOLOGY IS ASSOCIATED WITH LEFT VENTRICULAR OUTFLOW TRACT DIAMETER AND OBSTRUCTION RISK IN INTERRUPTED AORTIC ARCH

Background: Left Ventricular Outflow Tract Obstruction (LVOTO) is a major cause of morbidity and mortality in interrupted aortic arch (IAA). LVOT development may be flow-mediated, therefore IAA morphology may influence LVOT diameter and subsequent need for reintervention. Additionally contemporary long-term outcomes of IAA are sparse. We aimed to investigate the association of Interrupted Aortic Arch (IAA) morphology (IAA type and presence of arch branch aberrancy) with LVOT size and late LVOT reintervention.

METHODS AND RESULTS: All surgical IAA patients (2001-2022) were reviewed at a single institution (N=85). After exclusion of Truncus, Transposition, and Large AP window, 77 remained. Outcomes were compared as follows: IAA type A vs B; IAA with aortic arch aberrancy (AAb) vs none; IAA type B with concomitant aberrant subclavian (AbSCA) vs all others. Outcomes included LVOT diameter (mm), LVOTO at discharge (≥50mmHg), and LVOT reintervention. Fontan track patients were excluded from late LVOT reintervention analysis. Median follow-up was 7.6[5.5, 9.7] years.

Mean age was 10±19d and 3 died in hospital (4%). Seventy had biventricular repairs (90%). Type B IAA was commonest (B: N=51, 66% vs A: N=28 (31%). AAb occurred in 32% (N= 24) including: 21 with aberrant SCA, and 3 with right-sided arch. Twenty patients had both Type B IAA and AAb (26%). Type B patients weighed less [A: 3.54±1.05 vs B: 3.08±0.54kg p=0.02]. No weight differences occurred with AAb (p=0.17). Smaller LVOT diameter was associated with Type B [A: 5.40 (IQR:4.68, 5.80) vs B: 4.60 (IQR:3.92, 5.50) p=0.007], presence of AAb [AAb: 4.00 (IQR:3.70, 5.04) vs none: 5.15 (IQR:4.30, 5.68) p=0.006], and combined Type B with AbSCA [B+AAb: 4.00 (IQR:3.70, 5.02) vs Other: 5.00 (IQR:4.30, 5.68), p=0.002 Figure 1A]. Incidence of LVOTO at discharge was significantly higher among AAb (N=6, 25% vs N=1, 2% p=0.004) and B+AbSCA (N=1, 2% vs N=6, 30%, 0.002). At follow-up, 14 LVOT reinterventions occurred, mostly in type B with AbSCA (N= 7, 35%). Time-to-event analyses showed a signal towards significantly increased reintervention in this group [B+AbSCA vs other: log-rank p=0.11 Figure 1B].

Conclusion: IAA type B and arch aberrancy are associated with smaller LVOT diameter and early LVOTO, especially when combined. This may reflect lower flow in the proximal arch during development. Most long-term reinterventions occur in type B with concomitant aberrant subclavian, with a non-significant signal towards increased reintervention in these individuals. Type B and aberrant SCA should direct careful attention towards the risk of potentially small LVOT.