Two Different Methods of Determining B-Type Natriuretic Peptide, Either from Fingertip’s Capillary Blood or Antecubital Vein; A Comparison Regarding Diagnostic Accuracy in Patients with Chronic Heart Failure in NY

In recent years, several systems have been implemented to achieve quick and non-invasive measurements of B-type natriuretic peptide (BNP). Among them, Alere™ heart check (AHC) BNP test represents the most recent advancement. It is a rapid point of care immunoassay (POC), projected for measuring BNP directly from a capillary whole blood sample. This study aimed to compare analytical and clinical performances of this new POC to our reference method (Abbott architect system). 111 patients with stable chronic heart failure (CHF) referred to two cardiac rehabilitation centers were enrolled from December 2013 to January 2015. These patients were subjected to a simultaneous capillary (AHC) and plasma (Abbott) BNP measurements. Clinical and analytical performance of AHC were assessed and compared to the reference method. Capillary BNP showed a good correlation with the reference method (r = 0.94, P < 0.0001), although the values diverged when BNP was higher than 1500 pg /mL. Indeed, the AHC had a relatively poor precision and the coefficient of variability was 10.1% and 18% for low and high controls, respectively. However, both methods showed similar diagnostic performances in discriminating patients with heart failure in NYHA class I from those belonging to NYHA classes II-III, with values of area under the curve (AUC) of 0.983 and 0.984, respectively, and equivalent sensitivity, specificity and positive and negative likelihood ratios. The AHC BNP test is a good POC able to provide reliable information about hemodynamic status of CHF patients, especially of those belonging to NYHA classes I-III.