Borderline left ventricular hypoplasia without significant aortic or mitral stenosis: cardiac magnetic resonance criteria for biventricular repair

OBJECTIVES: Bi-ventricular (Bi-V) repair is viable in some patients with borderline left ventricular (LV) hypoplasia. We aimed to identify cardiovascular magnetic resonance (CMR) criteria predictive of successful primary Bi-V repair in neonates with borderline LV hypoplasia without significant mitral valve (MV) & aortic valve (AV) stenosis. METHODS: Retrospective study (2003-2024) of patients with borderline LV hypoplasia with CMR for decision-making. Patients MV stenosis (mean Doppler gradient >5 mmHg) and/or AV stenosis (peak Doppler gradient >20 mmHg) were excluded. Patients were divided into two groups: primary Bi-V repair and hybrid procedure. Outcomes were categorized as successful primary Bi-V repair, successful staged Bi-V repair and failure to achieve Bi-V repair. RESULTS: About 23/37 patients (62%) underwent successful primary Bi-V repair, 8/37 (22%) underwent staged Bi-V repair and 6/37 (16%) failed to achieve Bi-V repair. The successful primary/staged Bi-V repair group had higher LVEDVi (P < 0.002), higher blood flow volume through the ascending aorta (P < 0.012) and higher QAo/superior vena cava (QSVC) flow ratio (P = 0.034) compared to the failure to achieve Bi-V repair group. CMR LVEDVi cut-off of 27 ml/m2 had 87% sensitivity and 79% specificity (AUC 87.6%), and QAo threshold of 1.9 l/min/m2 had 65.2% sensitivity and 92.9% specificity (AUC 86.0%) for predicting successful primary Bi-V repair. About 7/31(22%) patients with Bi-V repair underwent reinterventions for LVOT obstruction & MV stenosis. CONCLUSIONS: In patients with borderline LV hypoplasia without MV/AV stenosis, CMR LVEDVi > 27 ml/m2 & QAo > 1.99 l/min/m2 were prognostic for successful primary biventricular repair.