Cardiorenal Syndrome in Cardiovascular Diseases: The Relationship Between Renal Function and Clinical Prognosis

Cardiorenal syndrome (CRS) is a complex condition involving bidirectional interactions between cardiovascular and renal dysfunction. Its pathophysiology includes hemodynamic abnormalities, venous congestion, neurohormonal activation, endothelial dysfunction, inflammation, and metabolic disturbances. This narrative review aims to analyze the mechanisms of CRS and assess the relationship between renal function and clinical prognosis in patients with cardiovascular diseases, focusing on mortality, heart failure hospitalization, kidney dysfunction progression, and treatment-related renal changes. The review synthesizes evidence from clinical guidelines, randomized trials, observational studies, and contemporary scientific publications, with particular attention to CRS classification, estimated glomerular filtration rate (eGFR), serum creatinine, albuminuria, biomarkers, and treatment outcomes. The evidence indicates that reduced eGFR, albuminuria, persistent congestion, and worsening renal function provide complementary prognostic information. An analysis of 3,715 EVEREST trial participants found that each 30% decline in eGFR was associated with an increased risk of death and cardiovascular death or heart failure hospitalization. The DOSE trial showed that intensive diuretic treatment could improve fluid removal and symptoms while increasing short-term creatinine elevations. These findings highlight the importance of interpreting renal function changes alongside congestion, hemodynamic stability, baseline kidney function, and treatment response. Comprehensive cardiorenal risk assessment should incorporate renal function, albuminuria, urine output, cardiac biomarkers, electrolyte status, and clinical response to treatment. Further prospective studies are needed to validate integrated risk models in diverse patient populations.