Preoperative, operative, and immediate postoperative predictors of the onset of low cardiac output syndrome in CHD

Background: Low cardiac output syndrome is a leading cause of morbidity and mortality after CHD surgery. Early, transparent risk estimation at paediatric cardiac ICU admission could guide monitoring and resource allocation. Objectives: To develop and evaluate a multivariable model that estimates the risk of low cardiac output syndrome using routinely available preoperative, intraoperative, and immediate postoperative variables. Methods: In this single-centre retrospective observational cohort, children ≤18 years undergoing CHD surgery between February 2023 and November 2024 were included. Low cardiac output syndrome was defined using prespecified criteria from the Paediatric Cardiac Critical Care Consortium. 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 low cardiac output syndrome. Independent predictors were higher surgical complexity ([RACHS-1] ≥ 4; AOR 3.69, 95% confidence intervals 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 AUROC 0.88 and AUPRC 0.71; at a prespecified decision threshold, accuracy 0.82, positive predictive value 0.66, sensitivity (recall) 0.50, F1 score 0.57, and negative predictive value 0.85. Conclusions: A parsimonious, interpretable model derived from routinely collected data identifies children at increased risk of low cardiac output syndrome at ICU arrival and can inform early intervention and staffing. Prospective multicentre validation and dynamic updating with continuous postoperative physiology are warranted.