Plasma N-terminal pro-brain natriuretic peptide and brain natriuretic peptide in assessment of acute dyspnea

Abstract

We examined the analytical correlation between non-radioimmunometric plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP) and evaluated whether NT-proBNP or BNP was superior in the emergency diagnosis of heart failure and whether this was influenced by age, gender, body mass index (BMI) and renal function. Data were collected prospectively from patients admitted to the emergency department for acute dyspnea. Plasma BNP (Triage, Biosite) and NT-proBNP (Elecsys, Roche diagnostic(R)) were measured at admission in addition to other standard biological parameters and clinical variables. Reference diagnosis was adjudicated by two independent cardiologists using the European society of cardiology guidelines. We evaluated the influence of creatinine clearance, age, gender and BMI on plasma BNP and NT-proBNP levels. One hundred and sixty consecutive patients were included: 84 females and 76 males, mean age 80.1 + 13.5 (16-98). The analytical correlation between the automated electro-chemiluminescence immunoassay for NT-proBNP and the single use fluorescence immunoassay for BNP was satisfactory using the equation: NT-proBNP = 1.1 BNP + 0.57 and a correlation r = 0.93. This was established over a wide range of concentration (5-6400 pg/ml for BNP). Areas under receiver operating characteristic (ROC) curve for BNP and NT-proBNP as a diagnostic marker for heart failure were 0.82 and 0.84, respectively and a BNP level of 150 pg/ml has similar sensitivity and specificity that NT-proBNP level of 1000 pg/ml. The correlation was not influenced by age, gender and BMI of patients. Renal dysfunction did not affect significantly this correlation (r = 0.93). We conclude that NT-proBNP, as assayed in the present study, correlates closely with BNP. This correlation is only slightly modulated by creatinine clearance values. The NT-proBNP appears as accurate as BNP according to area under ROC curve. Used in conjunction with other clinical information, rapid measurement of BNP or NT-proBNP is useful in establishing or excluding the diagnosis of congestive heart failure in patients with acute dyspnea.