Preoperative, Operative, and Immediate Postoperative Predictors of Onset of Low Cardiac Output Syndrome in Congenital Heart Disease

Background Low cardiac output syndrome (LCOS) is a leading cause of morbidity and mortality after congenital heart disease (CHD) surgery. Early, transparent risk estimation at pediatric cardiac intensive care unit admission could guide monitoring and resource allocation. Objective To develop and evaluate a multivariable model that estimates the risk of LCOS using routinely available preoperative, intraoperative, and immediate postoperative variables. Methods In this single-center retrospective observational cohort, children ≤ 18 years undergoing CHD surgery between February 2023 and November 2024 were included. LCOS was defined using prespecified criteria from the Pediatric Cardiac Critical Care Consortium (PC4). Candidate predictors were screened in univariate analyses; independent associations were estimated with multivariable logistic regression and backward elimination. Results Among 191 patients, 46 (24%) developed LCOS. Independent predictors were higher surgical complexity (Risk Adjustment for Congenital Heart Surgery [RACHS-1] ≥ 4; adjusted odds ratio [AOR] 3.69, 95% CI 1.38–9.81), preoperative inotrope use (AOR 2.75, 1.02–7.43), longer cardiopulmonary bypass duration (AOR 1.01 per minute, 1.00–1.02), and a greater number of prior cardiac operations (AOR 2.00 per operation, 1.34–2.97); higher operative weight was protective (AOR 0.92 per kilogram, 0.87–0.97). Model performance metrics were area under the receiver-operating characteristic curve (AUROC) 0.879 and area under the precision–recall curve (AUPRC) 0.706; at a prespecified decision threshold, accuracy 0.817, positive predictive value (PPV) 0.657, sensitivity (recall) 0.50, F1 score 0.568, and negative predictive value (NPV) 0.853. Conclusions A parsimonious, interpretable model derived from routinely collected data identifies children at increased risk of LCOS at ICU arrival and can inform early intervention and staffing. Prospective multicenter validation and dynamic updating with continuous postoperative physiology are warranted.