Across all inflammatory biomarkers evaluated—IL-6, hs-CRP, and NLR—the pooled evidence demonstrates: Consistently elevated risk of mortality and HF deterioration among patients with higher inflammatory marker levels; Robust associations across acute and chronic HF populations; Low-to-moderate heterogeneity, indicating reproducible findings across diverse geographic and clinical contexts; Strong biological plausibility, supporting systemic inflammation as a key driver of HF progression. This evidence concerns the gene IL6 and hydrops fetalis.