Utility of NT-proBNP for identifying LV failure in patients with acute exacerbation of chronic bronchitis

Abstract

Background: NT-proBNP has been widely regarded as a useful tool for diagnosis or exclusion of heart failure (HF) in many settings. However, in patients with acute exacerbation of chronic bronchitis (AECB), its roles have not been well described. The objective of this study was to evaluate the diagnostic performance of NT-proBNP for identifying left ventricular (LV) failure in such patients.

Methods and results: 311 AECB patients and 102 stable chronic bronchitis patients with no history of HF were enrolled. Plasma NT-proBNP concentrations were measured using Roche Elecsys. The European Society of Cardiology (ESC) diagnostic principles were adopted to identify HF and the diagnostic performance of NT-proBNP was evaluated by ROC. Our results showed, the median NT-proBNP level in patients with LV failure [4828.4 (2044.4-9203.6) ng/L] was significantly higher than that in those without LV failure [519.2 (179.1-1409.8) ng/L, p<0.001] and stable controls [207.5 (186.5-318.2) ng/L, p<0.001]. LV failure, renal function, atrial fibrillation and systolic pulmonary artery pressure were independent predictors of NT-proBNP levels (all p<0.05). The area under ROC curve (AUC) of NT-proBNP for identifying LV failure was 0.884, significantly superior to clinical judgment alone (AUC 0.835, p = 0.0294). At the optimal cutoff value of 935.0 ng/L, NT-proBNP yielded sensitivity 94.4%, specificity 68.2%, accuracy 74.3% and negative predictive value 97.6%. Adding the results of NT-proBNP to those of clinical judgment improved the diagnostic accuracy for LV failure.

Conclusion: As a tool for diagnosis or exclusion of HF, NT-proBNP can help physicians identify LV failure in patients with AECB.

Figure 1. Box plot of plasma NT-proBNP concentrations in AECB patients with or without LV failure.

Horizontal lines in the box indicate 25th, 50th and 75th percentiles, and I bars represent highest and lowest values. NT-proBNP: N-terminal pro-B type natriuretic peptide; AECB: acute exacerbation of chronic bronchitis; LV: left ventricular.

Figure 2. Receiver operating characteristic curve of NT-proBNP for diagnosis of LV failure in patients with AECB.

(A) All 311 patients included in the present study. The area under the receiver operating characteristic curve is 0.884 (95% confidence interval, 0.847 to 0.920) for all patients; (B) Patients stratified by age≤75 or>75 year. The AUC is 0.902 (95% confidence interval 0.846 to 0.944) for patients aged≤75 year, 0.872 (95% confidence interval 0.771 to 0.894) for patients aged>75 year.

Figure 3. Comparison of receiver operating characteristic curves among NT-proBNP, clinical judgment and both combine for diagnosis of LV failure in patients with AECB.

The area under the receiver operating characteristic curve (AUC) is 0.884 (95% confidence interval, 0.847 to 0.920) for NT-proBNP; 0.835 (95% confidence interval, 0.794 to 0.874) for clinical judgment alone; 0.923 (95% confidence interval 0.887 to 0.950) for both combine.