PEDS1: Development and Validation of a Novel Pediatric Mechanical Circulatory Support Risk Stratification Tool: ACTION MCS Risk Score

Abstract

Background: Risk stratification is important for decision-making in pediatric mechanical circulatory support (MCS). Current tools for risk stratification have not been validated. We sought to develop and validate a new risk stratification score for pediatric MCS. Methods: Data from the ACTION registry were used for model construction and model validation. A training dataset of 744 patients was used to identify risk factors for pediatric MCS mortality based upon pre-implantation characteristics. Key risk factors were combined to form the ACTION MCS Risk Score. A testing dataset of 235 patients was used to evaluate and compare model performance between the ACTION MCS Risk Score and INTERMACS Profiling, which was designed for adult MCS candidates but is often used in children. Results: There were 94 (13%) deaths among 744 patients in the training dataset. Based upon prior analyses, 9 risk factors were considered for inclusion in the score and these were condensed for simplicity to a total of 5 factors: Diagnosis, Weight, ECMO, Mechanical Ventilation and VAD type. The score is defined as the simple sum of each factor (Table 1). Increasing ACTION score is associated with increased mortality as seen in the Table 2, ranging from mortality of 2.72% for ACTION score 0, to mortality 34.1% for ACTION score 4 or higher. External validation in the testing dataset of 325 patients demonstrated superior model performance by the ACTION score compared to INTERMACS Profiling (ACTION score AUC=81 vs INTERMACS Profiling AUC=69). Conclusion: ACTION MCS Risk Score can be easily calculated at the bedside and offers useful prognostic information for pediatric MCS candidates. This is the first validated bedside risk assessment tool for pediatric MCS. Table 1. - Calculation of ACTION Score Risk Factor Value (Points) Diagnosis Dilated cardiomyopathy (0), Other (1) Weight (kg) >10 (0), 0-10 (1), ECMO No (0), Yes (1) Mechanical Ventilation No (0), Yes (1) VAD Type Other (0), Paracorporeal continuous (1) Table 2. - ACTION Score and mortality ACTION Score Number of patients Mortality (%) 0 184 2.72% 1 183 9.84% 2 159 9.43% 3 133 20.30% 4 or higher 85 34.1%