Over the last 5 years, several immunoassay methods for the measurement of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) became commercially available. Recent studies have confirmed the clinical usefulness of measurements of these cardiac natriuretic peptides for the prognostic stratification of patients with congestive heart failure, for the detection of left ventricular systolic and/or diastolic dysfunction, and for the differential diagnosis of dyspnea (1-4 ). However, to answer the most urgent requests of current clinical practice and to allow widespread use of BNP and NT-proBNP assays, some key issues had to be solved, such as increasing the sensitivity, precision, and experimental practicability (5 ). The aim of the present study was to evaluate and compare the analytical and clinical performance of five commercial natriuretic peptide immunoassays.Throughout this report, the values in healthy individuals and patients are reported as the range, median, and 25th and 75th percentiles. We enrolled 172 healthy adults (89 women and 83 men; age range, 16 -73 years; median age, 49.0 years; 25th percentile, 38 years; 75th percentile, 58 years). All participants were nonobese (body mass index, 19.4 -27.6 kg/m 2 , 24 kg/m 2 , 22.8 kg/m 2 , and 25.6 kg/m 2 ), normotensive (diastolic blood pressure, 60 -85 mmHg, 70 mmHg, 70 mmHg, and 80 mmHg; systolic blood pressure, 90 -140 mmHg, 120 mmHg, 102.5 mmHg, and 124.5 mmHg), and free from acute or chronic diseases. All participants had main plasma indices (including creatinine, urea nitrogen, glucose, uric acid, albumin, enzymes, electrolytes, and hemoglobin) within the appropriate reference intervals, and normal erythrocyte and leukocyte counts and urine analyses. All were asymptomatic and underwent a complete examination by a cardiologist, including a visit, standard 12-lead electrocardiogram, Doppler echocardiographic examination, and a bicycle stress test (when older than 50 years), which excluded silent heart disease.We also prospectively evaluated 279 consecutive patients with heart failure (211 men and 68 women; age, 20 -89 years, 66.0 years, 57.3 years, and 73 years). Cardiac morphology and function were assessed by two-dimensional echocardiography, or cardiac catheterization when needed. Idiopathic dilated cardiomyopathy was diagnosed in 136 patients (48.7%), whereas the other 143 patients suffered from secondary cardiomyopathy. Of these, 126 (45.1%) had ischemic cardiomyopathy. The inclusion criterion was a depressed (Ͻ50%) left ventricular ejection fraction [mean (SD), 31.8 (9.4)%; range, 10 -48%]. Heart failure severity was evaluated clinically according to the New York Heart Association (NYHA) classification: 32 patients were in functional NYHA class I, 133 were in class II, 81 were in class III, and 33 were in class IV, respectively. Patients were treated with a multidrug treatment (78% of patients treated with frusemide, 94% with angiotensin-converting enzyme inhibitor, 70% with carvedilol, and 58% with spironolactone), which was not stoppe...
