Significance of NT-pro-BNP in acute exacerbation of COPD patients without underlying left ventricular dysfunction

Background: B-type natriuretic peptide (BNP) and the N-terminal fragment of pro-BNP (NT-pro-BNP) are established biomarkers of heart failure. Increased levels of natriuretic peptide (NP) have been associated with poor outcomes in acute exacerbation of COPD (AECOPD); however, most studies did not address the conditions that can also increase NT-pro-BNP levels. We aimed to determine if NT-pro-BNP levels correlate with outcomes of AECOPD in patients without heart failure and other conditions that can affect NT-pro-BNP levels. Methods: We conducted a retrospective study in patients hospitalized for AECOPD with available NT-pro-BNP levels and normal left ventricular ejection fraction. We compared patients with normal and elevated NT-pro-BNP levels and analyzed the clinical and outcome data. Results: A total of 167 of 1,420 (11.7%) patients met the study criteria. A total of 77% of male patients and 53% of female patients had elevated NT-pro-BNP levels ( P =0.0031). NT-pro-BNP levels were not associated with COPD severity and comorbid illnesses. Log-transformed NT-pro-BNP levels were positively associated with echocardiographically estimated right ventricular systolic pressure ( r =0.3658; 95% confidence interval [CI]: 0.2060–0.5067; P <0.0001). Patients with elevated NT-pro-BNP levels were more likely to require intensive care (63% vs 43%; P =0.0207) and had a longer hospital length of stay ( P =0.0052). There were no differences in the need for noninvasive positive pressure ventilation ( P =0.1245) or mechanical ventilation ( P =0.9824) or in regard to in-hospital mortality ( P =0.5273). Conclusion: Patients with AECOPD and elevated NT-pro-BNP levels had increased hospital length of stay and need for intensive care. Based on our study, serum NT-pro-BNP levels cannot be used as a biomarker for increased mortality or requirement for invasive or noninvasive ventilation in this group of patients. Keywords: acute exacerbation of COPD, NT-pro-BNP, natriuretic peptide, COPD