The diagnostic value of N-terminal pro-B-type natriuretic peptide for low left ventricular ejection fraction by chronic kidney disease stage

BACKGROUND: Interpreting N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in chronic kidney disease (CKD) is challenging due to reduced renal clearance and frequent cardiovascular comorbidities. This study evaluated the diagnostic accuracy of NT-proBNP for identifying reduced left ventricular ejection fraction (LVEF < 50%) across different CKD stages. METHODS: This retrospective study included 840 patients with CKD Stages 3-5. Patients were categorized into reduced ejection fraction (REF, LVEF < 50%; n = 114) and preserved ejection fraction (PEF, LVEF ≥ 50%; n = 726) groups. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis, and stage-specific optimal cut-off values were determined by Youden's J statistic. Multivariate logistic regression was used to identify independent predictors of reduced LVEF. RESULTS: Median NT-proBNP levels were significantly higher in the REF group than in the PEF group (2,962 vs. 437 pg/mL, p < 0.001). In the overall cohort, NT-proBNP demonstrated good diagnostic performance (AUC: 0.805), with an optimal cut-off value of 1,562 pg/mL yielding 71.3% sensitivity and 77.8% specificity. Diagnostic accuracy differed according to renal function, being highest in Stage 3a (AUC: 0.872) and lowest in Stage 5 (AUC: 0.647). Optimal thresholds increased progressively with advancing CKD: 694 pg/mL (Stage 3a), 1,452 pg/mL (Stage 3b), 1,562 pg/mL (Stage 4), and 2,121 pg/mL (Stage 5). In multivariate analysis, log-transformed NT-proBNP remained an independent predictor of reduced LVEF (OR: 2.37, 95% CI: 1.96-2.86, p < 0.001), after adjustment for potential confounders including atrial fibrillation and valvular heart disease. CONCLUSIONS: NT-proBNP is a useful marker for detecting systolic dysfunction in patients with CKD. However, a single diagnostic threshold is inadequate; stage-specific cut-off values improve diagnostic precision, particularly in early-to-moderate CKD, and may facilitate earlier referral for echocardiographic evaluation.