Predicting Successful Biventricular Conversion in Patients with Palliated Hypoplastic Left Ventricles

Objectives For patients with palliated hypoplastic left ventricles (HLV), the decision for biventricular (BiV) conversion can be challenging. We sought to identify preoperative characteristics that predict successful BiV repair. Methods Retrospective study from 2005-2025 of patients with palliated HLV who underwent BiV conversion. All had preoperative cardiac magnetic resonance imaging or computed tomography, and catheterization data. The primary composite outcome included death, transplant, or BiV repair takedown. The secondary composite outcome included unexpected re-intervention related to LV dysfunction or LV failure. Results Of 175 patients, 51% had prior LV recruitment, 42% had abnormal segmental anatomy, 51% had right dominant atrioventricular canal defect, 44% had abnormal conotruncal anatomy, and 13% had endocardial fibroelastosis (EFE). 17% met the primary outcome and 42% met the secondary outcome. For 119 (68%) with at least 3 years of follow-up, CART analysis identified risk factors of EFE, left ventricular end-diastolic pressure (LVEDP), mitral valve orifice area index, right ventricular mass index, and heart rate, with an area under the curve of 0.75 (95% CI 0.62-0.87) on out-of-sample cross-validation. By multivariate logistic regression, EFE (OR 5.85, p=0.01), LVEDp (OR 1.27, p=0.03) and right ventricular mass index (OR 1.07, p <0.01) were associated with the primary outcome at 3 years. Conclusions We present a CART-derived risk stratification model that identifies combinations of preoperative factors associated with LV adequacy following biventricular repair. Although the model requires external validation, it provides empirically derived thresholds that may complement clinical assessment.