Dilated cardiomyopathy (DCM) is a common cause of sudden cardiac death and heart failure in children, its different etiologies are significantly associated with the prognosis of children with DCM. However, there is a lack of accurate etiologic diagnosis and effective risk stratification programs. Primary DCM has the highest prevalence and relatively poor prognosis, especially in children with genetic factors. Therefore, the analysis of mortality risk factors based on genetic background would be beneficial for the accurate prognosis and risk stratification of children with DCM.

To explore the proportion of genetic etiology, genetic characteristics and factors related to poor prognosis of primary DCM in children.

The clinical data and genetic testing results of 42 children with primary DCM who were hospitalized in Hebei Children's Hospital from July 2018 to December 2022 and completed genetic testing were retrospectively collected, and the included children were regularly followed up in the cardiology outpatient department of Hebei Children's Hospital after discharge. With the time of death or 2022-12-31 as the end point of follow-up, the children were divided into the death group (9 cases) and survival group (33 cases) according to the follow-up outcomes. Survival curves of the children were plotted using the Kaplan-Meier method, and comparisons between groups were performed using the Log-rank test. Multivariate COX proportional risk model was used to analyze the risk factors for death.

The median age of first diagnosis was 12 (7, 96) months, and the median follow-up time was 24 (9, 36) months. The median follow-up time was 8 (0, 11) months in the death group and 30 (12, 39) months in the survival group, the difference was statistically significant (Z=-2.19, P<0.05) . The proportion of male, heart function grade Ⅲ/Ⅳ and gene mutation positive in the death group was higher than that in the survival group, and the left ventricular short axis shortening rate (LVFS) was lower than that in the survival group (P<0.05) . The positive rate of gene mutation was 38.1% (16/42) , of which 25.0% (4/16) were spontaneous mutations and 61.9% (26/42) were negative mutations. All the 9 children in the death group died within 1 year after diagnosis, including 8 patients with positive gene mutation (50.0%, 8/16) and 1 patient with negative gene mutation (3.8%, 1/26) , with statistically significant differences between the two groups (P<0.05) . The heterozygous variation of CSRP3 (c.190C>T) in the dead children with negative gene mutation was classified as unclear clinical significance. The Kaplan-Meier survival curve of the children was plotted, and the Log-rank test results showed that the survival rate of children with negative gene mutation was higher than that of children with positive gene mutation (χ²=18.1, P<0.001) . Multivariate COX proportional risk model analysis showed that gene mutation [HR=23.91, 95%CI= (1.80-317.21) , P=0.016] and cardiac function grade Ⅲ/Ⅳ [HR=11.29, 95%CI (1.13-112.68) , P=0.039] were risk factors for death in children with DCM.

In this study, 38.1% of children with primary DCM were associated with genetic etiology. The first year after diagnosis is the high incidence of death of children with DCM, and the prognosis of children with positive gene mutation is worse. The presence of pathogenic gene mutation and the cardiac function grade of Ⅲ~Ⅳ at the first diagnosis are independent risk factors for death in children.