Abstract 13178: A Novel, Data-Driven Approach to Classify Critical Left Ventricular Outflow Tract Obstruction Using Pre-Intervention Echocardiographic Measurements: A Report From The Congenital Heart Surgeons’ Society Data Center

Abstract

Objective: Critical left ventricular outflow tract obstruction (LVOTO) has been traditionally classified by aortic and mitral valvar pathology. We aimed to determine if baseline qualitative and quantitative echocardiographic measures alone could define new groups of patients with greater clinical relevance. Methods: Pre-intervention transthoracic echocardiograms for 651 neonates with Critical LVOTO were interpreted by one pediatric cardiologist according to a standardized protocol. Cluster analysis, with 136 echocardiographic measures, was used to group the patients. Variables defining each group were identified by multinomial regression. Results: Cluster analysis categorized the 651 neonates into groups of 215 (Group 1), 338 (Group 2), and 98 (Group 3) patients (Panel A). Aortic valve atresia and left ventricular (LV) end diastolic volume were identified as significant discriminating variables. LV size was largest in Group 3 and smallest in Group 2. Aortic atresia was most prevalent in Group 2 and least prevalent in Group 3. The distribution of these and other variables is shown in Panel B. Balloon valvotomy was the first intervention in 9% (19/215), 2% (6/338), and 61% (60/98) (p<0.0001). In those with an initial operation, single ventricle palliation was performed in 90% (176/215), 98% (326/338), and 58% (22/38) (p<0.0001). Overall mortality in each group was 27% (59/215), 41% (138/338), and 12% (12/98) (p<0.0001). Conclusions: Using a completely data-driven approach, we identified three novel groups, primarily based on baseline LV size, that correlate with management strategy and overall mortality. These groups roughly correspond anatomically with multi-level LV hypoplasia, hypoplastic left heart syndrome, and critical aortic stenosis, respectively. Our analysis suggests that a more useful classification of critical LVOTO may require more detailed measurements, especially of LV size, than a simplistic scheme limited to valvar pathology.