PM1041: Predictors of Re-intervention in Patients with Atrioventricular Canal Defect Undergoing Mitral Valve Repair

Background: Acute outcomes and survival after atrioventricular canal (AVC) repair in the current era are excellent, yet despite surgical advances ~15% of patients require subsequent mitral valve (MV) repair, and, in some cases, multiple MV surgeries. In order to inform surgical decision-making and reduce the burden of MV surgery, we aim to determine predictors for re-intervention following MV repair in AVC patients, with a focus on postoperative transesophageal echocardiography (TEE).

Methods: We reviewed all patients undergoing MV repair after prior AVC repair at Boston Children’s Hospital between 2010-2020. Freedom from death and MV re-intervention after MV repair were evaluated with competing risk analysis. Cox logistic regression was used to identify predictors of MV re-intervention.

Results: A total of 137 MV repairs were performed in 113 patients, with 23 patients undergoing two repairs and one patient undergoing three repairs. Most repairs were performed in patients with repaired complete AVC (64%) (vs. 20% transitional AVC and 16% partial AVC) and balanced AVC (77%) (vs. 21% right dominant and 2% left dominant). Parachute MV was present in 27% of repairs and double orifice MV in 13%. Median age at MV repair was 12 months.

There were 7 deaths and 47 re-interventions over median follow-up of 12.2 months. The re-intervention rate was 29.2% (95% CI: 21.2, 37.6) at 12 months. Multivariate analysis identified age ≤ 6 years, partial AVC (vs. complete), postoperative left ventricular systolic dysfunction, and postoperative TEE mean mitral stenosis (MS) gradient ≥ 5 mmHg as risk factors for MV re-intervention. Grade of mitral regurgitation (MR) on postoperative TEE was not an independent risk factor, but re-intervention rates were high when MS gradient ≥ 5 mmHg and mild MR were present on postop TEE (47%) and even higher when MS gradient ≥ 5 mmHg and > mild MR (73%)

Conclusion: Re-intervention rates remain high for patients with repaired AVC undergoing subsequent MV surgery, particularly for patients with MS gradient ≥ 5 mmHg and ≥ mild MR on postoperative TEE.