Monitoring of patients with heart failure.

The recent guidelines of the European Society of Cardiology, recommends laboratory testing as an essential part of the evaluation of the patient presenting with acute or chronic heart failure. The decrease in BNP has been included as a treatment goal for the management of acute heart failure. As for other properties it is important to define what difference can be considered as a real change of the marker in serial measurements. Therefore, knowledge of pathophysiological influences and pre-analytical issues as well as the intraindividual variability of BNP and N-terminal proBNP (NT-proBNP) due to analytical imprecision and biological variation is crucial. Erroneous test results with BNP or NT-proBNP assays are rare but may occasionally occur analytical interferences and should be suspected if the results do not suit the clinical picture or the serial kinetics. Although BNP assays correlate closely, due to lack of standardization no two BNP assays are analytically equivalent, and the same assay must be used for serial measurement. The in-vitro stabilities of BNP and NT-proBNP are sufficient for routine use, and blood sampling for BNP or NT-proBNP directly after arrival without a standardized period of rest is feasible, however, heavy physical exercise should be avoided before blood sampling. To be on the safe side a period of 10 minutes rest before blood sampling is recommended. BNP and NT-proBNP are suitable for heart failure monitoring, and BNP and NT-proBNP changes >50% from baseline correlated well with clinical course and a reduction of mortality in heart failure patients.