The Worsening Renal Perfusion Index predicts the prognoses of heart failure patients treated with sacubitril/valsartan

Introduction: Sacubitril/valsartan (S/V) reduces all-cause mortality in patients with heart failure with reduced ejection fraction (HFrEF), but it may decline their estimated glomerular filtration rates (eGFR). In addition to eGFR, this clinical study aimed to develop a blood urea nitrogen (BUN)-based index to evaluate the status of renal perfusion and then identify predictors of all-cause death or heart transplant in patients with HFrEF receiving S/V.Methods: From the recruited 291 patients with HFrEF who were prescribed S/V from March 2017 to March 2019, we collected demographic, drug history, laboratory, echocardiographic, and clinical data from one year before S/V initiation until December 2020. Regression analysis was conducted by fitting Cox's models with time-dependent covariates for the survival time and applying the modern stepwise variable selection procedure. The smoothing spline method was used to detect nonlinearity in effect and yield optimal cut-off values for continuous covariates.Results: In the Cox's model, decreased hemoglobin level, decreased mean left ventricular ejection fraction, declined daily dose of S/V, decreased eGFR within 3 months, and increased BUN levels within 1 month and 9 months over time were significantly associated with an increased risk of all-cause death or heart transplant in patients with HFrEF.Conclusions: Adequate maintenance of renal perfusion is crucial for the continuous use of S/V and to avoid worsening renal function in patients with HFrEF. We defined the maximum increase in BUN levels within a specified period as the Worsening Renal Perfusion Index (WRPSV Index) to capture the prognostic effect of renal hypoperfusion in patients with HFrEF.