Background: Renal dysfunction was reported to be closely associated with clinical outcomes in patients with chronic heart failure (CHF). Renal tubulointerstitial damage has been shown to be an important factor in the development of renal dysfunction as well as glomerular damage. However, the impact of renal tubular damage on clinical outcomes in patients with CHF remains to be determined.
Methods and results: Urinary β2-microglobulin-creatinine ratio was measured in 315 patients with CHF. Renal tubular damage was defined as a urinary β2-microglobulin-creatinine ratio ≥ 300 μg/g, as previously reported. Patients were prospectively followed up for a median period of 1097 days. There were 91 cardiac events, including 16 cardiac deaths and 75 rehospitalizations for worsening heart failure. Log10 urinary β2-microglobulin-creatinine ratio was increased with worsening New York Heart Association functional class. Multivariate analysis revealed that renal tubular damage was an independent predictor of cardiac events. Kaplan-Meier analysis demonstrated that the rate of cardiac events was higher in patients with renal tubular damage compared with those without it. Patients were divided into 4 groups according to the presence of chronic kidney disease and renal tubular damage. The Cox proportional hazard analysis revealed that comorbidity of chronic kidney disease and renal tubular damage was associated with the highest risk for cardiac events compared with other groups.
Conclusions: Renal tubular damage was related to the severity of heart failure and was associated with poor outcomes in patients with CHF. Renal tubular damage could add clinical information to chronic kidney disease in patients with CHF.
Keywords: heart failure; renal tubular damage; urinary β2–microglobulin.