<p>Congenital heart disease (CHD) represents the most prevalent and life-threatening birth defect. The identification of underlying factors contributing to abnormal cardiac development can offer valuable insights for the comprehensive medical management of affected pediatric patients. This study aimed to investigate the role and underlying mechanisms of GATA3-AS1 in the progression of CHD. The proliferation ability and apoptosis level of AC16 cardiomyocytes overexpressing GATA3-AS1 were detected by CCK-8 assay and flow cytometry. The downstream target miRNAs and mRNAs of GATA3-AS1 were validated using qPCR and western blot to elucidate the GATA3-AS1-associated ceRNA regulatory network. The interaction between GATA3-AS1 and its downstream target genes was validated using the dual-luciferase reporter assay. Finally, the expression patterns of GATA3‑AS1 and its downstream target genes were validated in clinical samples. Cellular functional assays demonstrated that the overexpression of GATA3-AS1 significantly suppressed the proliferation of AC16 cardiomyocytes while inducing apoptosis in these cells. The qPCR analysis revealed that, in AC16 cells overexpressing GATA3-AS1, the expression levels of NR2F2 were significantly upregulated, whereas the expression levels of miR-149-3p and miR-6769b-5p were significantly downregulated. Additionally, Western blot analysis further validated the significant upregulation of NR2F2 protein expression. The dual-luciferase reporter gene assay confirmed that GATA3-AS1 regulated cellular biological behavior by competitively binding to miR-149-3p with NR2F2. Finally, qPCR confirmed that the expression of GATA3-AS1, miR-149-3p, and NR2F2 in clinical samples were consistent with cytological experiments. GATA3-AS1 regulates the proliferation and apoptosis of AC16 cells via the GATA3-AS1/has-miR-149-3p/NR2F2 axis, potentially contributing to the formulation of more personalized and effective medical management strategies for patients with CHD.</p>