Abstract: Background：There were still few studies on the combination of real-time three-dimensional echocardiography(RT-3DE) and two-dimensional speckle tracking imaging(2D-STI) in evaluating left ventricular systolic synchronization for children with viral myocarditis(VMC). Objective：To evaluate the value of RT-3DE and 2D-STI in predicting the prognosis of children with viral myocarditis. Design：Retrospective cohort study. Methods：A cohort of VMC children hospitalized in Fujian Children's Hospital from January 2019 to January 2022 was collected. The patients were followed up for half a year after discharge taken as the end point. According to the follow-up, the patients were divided into poor prognosis group and good prognosis group. The two groups were further divided into training set and verification set according to the proportion of 7∶3 by random number table. After admission, all the children were given routine treatment. Two physicians used the same ultrasound equipment to perform 2D-STI that the apical two-chamber section, apical four-chamber section, apical section and papillary muscle section of the short axis of the left ventricular posterior wall were examined to measure the peak late diastolic strain rate (Asr), systolic peak strain rate (Ssr), systolic peak strain rate (ε), early diastolic peak strain rate (Esr) in middle segment (MID), apical segment (APX) and basal segment (BAS) of left ventricular wall. RT-3DE parameters were also measured including maximum difference of minimum end-systolic volume time of 16 and 12 segments of left ventricle (Tmsv-16-Dif, Tmsv-12-Dif), measurement of standard deviation (Tmsv16-SD, Tmsv12-SD) and heart rate correction (Tmsv16-SD%, Tmsv12-SD%, Tmsv16-Dif%, Tmsv12-Dif%). Each ultrasound physician repeated the measurement for 3 times to take the average value. According to the 2D-STI, RT-3DE parameters and laboratory indexes of VMC children on admission, the predictive factors were screened by univariate analysis, Lasso and logistic regression analysis, and a model for predicting the prognosis of VMC children was constructed. The predictive effect was verified by training set and verification set. Main outcome measures：The predictive value of 2D-STI parameters and RT-3DE parameters for the prognosis in children with VMC. Results：A total of 157 children with VMC were included into the analysis, including 82 males and 75 females. The median age was 6.72(3.20, 10.61) years. The median follow-up duration was 8.29(7.37, 11.41) months. There were 121 cases with good prognosis, including 84 cases in the training group and 37 cases in the verification group. There were 36 cases with poor prognosis, including 26 cases in the training group and 10 cases in the verification group. Nineteen independent factors affecting the prognosis of VMC were included as follows: 2D-STI parameters in the long axis direction of left ventricular wall of posterior wall-BAS-ε, inferior wall-BAS-ε, anterior wall-MID-Esr value, posterior wall-BAS-Esr value, inferior wall-BAS-Esr value, inferior wall-APX-ε value, posterior wall-APX-Esr value, and inferior wall-APX-Esr value; RT-3DE parameters of Tmsv12-SD, Tmsv12-SD%, Tmsv12-Dif%, Tmsv16-SD, Tmsv16-SD%, Tmsv16-Dif, Tmsv16-Dif%; laboratory inspection indicators of WBC, hs-CRP, CK, cTn. The model for predicting the prognosis of children with VMC has good differentiation and calibration. The area under the curve of the training set and verification set were 0.861 (95%CI: 0.812-0.889) and 0.842 (95%CI: 0.807-0.887), and the consistency index of calibration curve of training set and verification set were 0.886 and 0.881 respectively. Conclusion：The poor prognosis prediction model of VMC constructed in this study is of good value in predicting the prognosis of children with VMC.

Key words: Real-time three-dimensional echocardiography, Two-dimensional speckle tracking imaging, Viral myocarditis, Children, Prognosis