Determination of B-Type Natriuretic Peptides: Clinical And Analytical Quality
B-type natriuretic peptide (BNP), a neurohormone synthesized in the cardiac ventricles, is released as preproBNP and then enzymatically cleaved to the N-terminal-proBNP (NT-proBNP) and BNP upon ventricular myocite stretch. This hormone has a role in the body's defense against hypertension and plasma volume expansion. Measurements of circulating B-type natriuretic peptides have been shown to be of diagnostic value in patients with heart failure. BNP levels correlate with the severity of heart failure, as well as with prognosis. Better control of the preanalytical and analytical sources of variations will undoubtedly lead to improvement in B-type natriuretic peptides measurements. A number of preanalytical and analytical factors including specimen type and stability, assay imprecision, and standardization are reviewed here. Further research is required to better define the performance characteristics necessary for assays bearing the designation natriuretic peptides. These characteristics include developing guidelines for the total analytical error from a careful review of the intraindividual biological variability of the analyte under conditions that will be encountered in clinical practice, then validating these guidelines in the clinical setting, and completing the standardization efforts.
The Efficacy of Different Therapy Protocols for Heart Failure in Patients with Heart Failure and Increased Natriuretic Peptide Level
Natriuretic peptide BNP might be clinically useful for monitoring treatment effects in patients with heart failure (HF). In order to investigate the pharmacological effects of different therapy protocols for patients with HF based on the BNP level before and after therapy, we performed an open randomized comparative trial. Sixty-two HF patients with increased natriuretic peptide level, aged 55.82±9.09, II-III NYHA functional classes, ejection fraction (EF) <45%, received a 12-week treatment with either traditional pharmacotherapy for HF with ACE inhibitors and β-blockers (1st group), or ACE inhibitors and angiotensin II receptor blockers (ARBs) (2nd group), or β-blockers and ARBs (3rd group), and ACE inhibitors, β-blockers and ARBs (4th group). We evaluated the BNP plasma level, hemodynamic state (pulmonary capillary wedge pressure (PCWP), cardiac output (CO), EF and exercise capacity. The BNP plasma level decreased significantly in the 4th group of patients who received ACE inhibitors, β-blockers and ARBs, in comparison to other groups. A beneficial influence on hemodynamic and exercise capacity was significantly pronounced in this group, compared to the other therapy regimes. In conclusion, the therapeutic protocol: ACE inhibitors, β-blockers and ARBs in HF patients with increased natriuretic peptide level significantly improves the quality of life, left ventricular function, hemodynamic parameters and exercise capacity. All these changes were accompanied with a decreasing of the BNP plasma level.