ObjectiveTo quest the risk factors of poor prognoses in children with tetralogy of Fallot (TOF) during perioperative period and evaluate its clinical application values.MethodsA retrospective analysis of the clinical data of 119 children who underwent one-stage correction of TOF in Guangdong Provincial People's Hospital from September 2016 to January 2019. The cohort includes 75 males and 44 females, with ages ranging from 3.2-137.1 (13.2±1.4) months and weights ranging from 4.6-21.0 (8.3±0.2) kg. Perioperative poor prognosis was defined as duration of mechanically assisted ventilation >48 h or secondary intubation, vasoactive-inotropic score (VIS) within 48 h >40, postoperative length of stay >14 d, and the occurrence of the major adverse events. Major adverse events were defined as early death, malignant arrhythmia, low cardiac output syndrome, non-fatal cardiac arrest, postoperative reintervention, diaphragm paralysis, and other clinical complications. Univariate and multivariate logistic analyses were used to analyze the correlation between risk factors and poor prognoses.ResultsThere was 1 perioperative death, and 9 with major adverse events. Variables selected by Least Absolute Shrinkage and Selection Operator (LASSO) included 2 preoperative variables (McGoon index, aortic root diameter index) and 4 intra-operative variables [left-right direction of bicuspid pulmonary valve, total length of right ventricular outflow tract (RVOT) incision index, pulmonary valve with commissurotomy, and minimum temperature in cardiopulmonary bypass (CPB)]. Univariate and multivariate logistic analyses were used to the above factors, respectively. The variables with statistical significance (P≤0.05) were McGoon index, aortic root diameter index, left-right direction of bicuspid pulmonary valve, and minimum temperature in CPB. A nomogram was established based on the above factors, and the results showed that the left-right direction of bicuspid pulmonary valve was more risky than the tricuspid pulmonary valve and the anterior-posterior direction of bicuspid pulmonary valve. The lower the McGoon index, the higher aortic root diameter, and the lower temperature in CPB, the higher risk of poor prognostic events in children with TOF.ConclusionThe left-right direction of the pulmonary bicuspid valve has a higher risk of poor prognosis than the tricuspid pulmonary valve and the anterior-posterior direction of bicuspid pulmonary valve. With the smaller McGoon index and the larger aortic root diameter, the risk of poor prognoses in children with TOF is higher. The temperature in CPB being lower than medium-low temperature obviously relates to the high incidence of poor prognostic events, which can be used as an auxiliary reference standard for decision-making in pediatric TOF surgery in the future.