The association between NT-proBNP levels, functional capacity and stage in patients with heart failure.

Objective: Amino-terminal probrain natriuretic peptide (NT-proBNP), a biologically inactive derivative of BNP, is clinically more useful owing to its longer half-life, higher plasma concentrations, lesser variation among individuals, and higher in vitro stability. In this regard, NT-proBNP may be a better indicator of the severity of ventricular dysfunction. In this study, the association of NT-proBNP levels with functional capacity and stage of heart failure was explored in patients with CHF. Also, we particularly focused on the presence and significance of neurohormonal activation in the group of patients classified as stage-A according to ACC/AHA guidelines.

Methods And Results: 64 patients with CHF (31 men, 33 women; mean age 58.26 +/- 10.59 y) and 36 healthy controls (24 men, 12 women; mean age 57.47 +/- 10.83) were included in this study. The New York Heart Association (NYHA) classification system (I, II, III, IV) was used to define the functional capacity; and the stage of the heart failure was based on the ACC/AHA guidelines (A, B, C, D). Healthy female participants had higher NT-proBNP levels compared to their male counterparts (p < 0.001). Left ventricular ejection fraction (LVEF) did not correlate significantly with functional capacity and stage of the disease. CHF patients had higher NT-proBNP compared to controls (p < 0.001). There was a positive correlation between NT-proBNP and functional capacity in patients, and NT-proBNP increased significantly with each increasing class of the disease. Similarly, a positive correlation existed between the stage of heart failure and NT-proBNP levels, which increased significantly with increasing stages of the disease. Patients with NYHA I and stage A disease had higher NT-proBNP levels compared to controls (p = 0.04).

Conclusions: The severity of CHF can be objectively assessed by measuring the circulating levels of NT-proBNP. Even in NYHA I and stage A disease, NT-proBNP levels are higher compared to controls (p = 0.04). NT-proBNP can provide objective information regarding the severity of the disease and also aid in treatment decisions in patients with CHF.