Midregional Pro–Atrial Natriuretic Peptide for the Diagnosis of Cardiac-Related Dyspnea according to Renal Function in the Emergency Department: A Comparison with B-Type Natriuretic Peptide (BNP) and N-Terminal ProBNP

BACKGROUND Although renal dysfunction influences the threshold values of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) in diagnosis of cardiac-related dyspnea (CRD), its effects on midregional pro–atrial natriuretic peptide (MR-proANP) threshold values are unknown. We evaluated the impact of renal function on MR-proANP concentrations and compared our results to those of BNP and NT-proBNP. METHODS MR-proANP, BNP, and NT-proBNP concentrations were measured in blood samples collected routinely from dyspneic patients admitted to the emergency department. Patients were subdivided into tertiles based on their estimated glomerular filtration rate [eGFR, in mL · min−1 · (1.73 m2)−1]: tertiles 1 (<44.3), 2 (44.3–58.5), and 3 (≥58.6). RESULTS Of 378 patients studied, 69% (n = 260) had impaired renal function [<60 mL · min−1 · (1.73 m2)−1] and 30% (n = 114) had CRD. MR-proANP, BNP, and NT-proBNP concentrations were significantly increased in patients with impaired renal function. In each tertile, all peptides remained significantly increased in CRD patients by comparison with non-CRD patients. By ROC analysis, MR-proANP, BNP, and NT-proBNP threshold values for the diagnosis of CRD increased as eGFR decreased from tertile 3 to tertile 1. Areas under the ROC curve for all peptides were significantly lower in tertile 1. Using adapted thresholds, MR-proANP, BNP, and NT-proBNP remained independently predictive of CRD, even in tertile 1 patients. CONCLUSIONS Renal function influences optimum cutoff points of MR-proANP for the diagnosis of CRD. With use of an optimum threshold value adapted to the eGFR category, MR-proANP remains as effective as BNP and NT-proBNP in independently predicting a diagnosis of CRD in the emergency department.