Association of left-heart dysfunction with severe exacerbation of chronic obstructive pulmonary disease - Diagnostic performance of cardiac biomarkers

Rationale: Cardiac biomarkers are used to distinguish acute dyspnea due to left-heart dysfunction from that of pulmonary origin. However, they have not been assessed in the specific setting of acute exacerbation of chronic obstructive pulmonary disease (AECOPD), where they might be released without left-heart impairment. Objective: To assess the accuracy of troponin T and of amino-terminal pro-brain natriuretic peptide (NT-proBNP) in the diagnosis of AECOPD associated with left ventricular (LV) dysfunction. Methods: Both biomarkers were measured in 148 consecutive patients on intensive care unit admission,for AECOPD. A panel of physicians adjudicated blindly the cause of AECOPD to be unlikely, possibly associated, or definitely associated with LV dysfunction. Measurements and Main Results: The final diagnosis was AECOPD definitely associated with acute left-heart dysfunction in 31.1%, possibly associated with LV dysfunction in 13.5%, and probably not associated with LV dysfunction in 55.4%. Both NT-proBNP and troponin T levels were significantly different among the three groups. The area under the receiver operating characteristic curve was greater for NT-proBNP (0.95 vs. 0.67). A cutoff of 1,000 pg/ml was accurate to rule out left-heart involvement in AECOPD (sensitivity, 94%; negative predictive value, 94%; negative likelihood ratio, 0.08). A cutoff of 2,500 pg/ml had the best operating characteristics to rule in the diagnosis (positive likelihood ratio, 5.16). Left-heart involvement in AECOPD was the only variable independently associated with increased secretion of NT-proBNP (odds ratio, 74; 95% confidence interval, 15-375; p = 0.0001). Conclusion: NT-proBNP and troponin T are useful in excluding AECOPD associated with left ventricular dysfunction. NT-proBNP was the more accurate of the two.