NPPB and atrial septal defect: The small sample size resulted in insufficient statistical power to quantify their prognostic weight—after adjusting for HF-related factors (e.g., modified Ross classification, NT-proBNP), the prognostic impact of CHD subtypes became non-significant (VSD vs. ASD: HR = 1.08, 95% CI: 0.62–1.89, p = 0.78).