Back to 2026 Abstracts
Complete AVSD And Discrete Subaortic Membrane: Congenital And Repair-Associated Risk Factors For LVOT Obstruction
Andrei-Antonio Caracioni, MD, Ibrahim T. Abdelmoneim, MD, PhD, MSc, Julia Gaal, Sitaram Emani, MD, Pedro J. del Nido, MD, Ingeborg Friehs, MD.
Boston Children's Hospital, Boston, MA, USA.
ObjectiveLeft ventricular outflow tract (LVOT) obstruction, commonly represented by a discrete subaortic membrane/stenosis (DSS), after complete atrioventricular septal defect (cAVSD) repair, remains the second most common indication for reoperation. In a multivariable propensity-matched case-control study, we aimed to determine whether altered LV geometry following complete AVSD repair predicts the occurrence of DSS.
MethodsPatients with isolated cAVSD and DSS (1994-2026) were matched 1:1 on age, sex, and repair technique to patients with cAVSD without DSS. LV geometry was assessed by LVOT-septal° and aortic-mitral (AV-MV) plane°.
ResultsWe identified 14 patients undergoing cAVSD repair at median age of 3.68months (IQR:2.08-4.38) requiring DSS resection at a median interval post-cAVSD repair of 3.48years (IQR:1.35-5.75). Matched controls underwent cAVSD repair at 3.35months (IQR:2.31-4.03). With a median distance to the AV annulus of 4.5mm (IQR:5.5-7.5), valve peeling was required in 5/14 patients. Accessory mitral chordae required resection/division in 6/14 patients at both cAVSD and DSS repair, while 6/14 underwent LVOT chordae/muscle bundle intervention only at DSS repair. 8/14 required additional left cleft repair at the time of DSS resection. While AV-MV plane° was not different in patients developing DSS versus matched patients (p>0.05), the LVOT-septal° was significantly steeper in patients who developed DSS after cAVSD repair (DSS: 129°±6.3° vs control: 138°±6.6°; p<0.001).
ConclusionWhile AV-MV plane° remained unchanged, a steeper post-repair LVOT-septal° emerged as a potential repair-induced predictor of DSS occurrence. Management of the left AV valve, particularly cleft repair and the treatment of subvalvular mitral valve disease, plays a crucial role in DSS.
Back to 2026 Abstracts
