Chest
Volume 136, Issue 3, September 2009, Pages 671-677
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Original Research
Pleural Effusion
Biomarkers of Heart Failure in Pleural Fluid

https://doi.org/10.1378/chest.09-0270Get rights and content

Background

The objective of this study was to compare the diagnostic accuracy of pleural fluid brain natriuretic peptide (BNP), N-terminal pro-BNP (NT-pro-BNP) and ST2, which are biomarkers of myocyte stress, for diagnosing pleural effusions due to heart failure (HF). BNP and ST2 have not been previously evaluated in pleural fluid.

Methods

The three biomarkers were measured in the pleural fluid of 90 cardiac effusions and 91 noncardiac effusions by commercially available methodologies. The area under the curve (AUC) quantified the overall diagnostic accuracy of the tests.

Results

Pleural fluid NT-pro-BNP, BNP, and ST2 demonstrated AUCs of 0.96, 0.90 and 0.59, respectively, for diagnosing effusions due to HF. The cutoff values of 1,300 and 115 pg/mL, respectively, for NT-pro-BNP and BNP had the best discriminating properties. The reference level for BNP was particularly accurate in men > 75 years of age (AUC, 0.98), but age, gender, and serum creatinine level did not influence the NT-pro-BNP levels. Of the 20 patients whose cardiac effusions were misclassified as exudates by the criteria of Light et al, 18 patients (90%) and 14 patients (70%), respectively, would have been correctly categorized by NT-pro-BNP and BNP, whereas only 10 patients (50%) would have been appropriately classified by the serum-pleural protein gradient.

Conclusions

The pleural fluid NT-pro-BNP level is very useful in establishing the diagnosis of HF-associated effusions, and it confirms this diagnosis better than pleural BNP levels. The measurement of NT-pro-BNP rather than the serum-to-pleural protein gradient is recommended for identifying mislabeled cardiac transudates. The pleural fluid ST2 level is not helpful in diagnosing HF.

Section snippets

Materials and Methods

We performed a retrospective analysis of patients with pleural effusion from a prospectively maintained database. To do so, we selected 86 consecutive patients from a previous prospective study6 (50 patients with HF and 36 patients with noncardiac effusions), adding 95 newer patients (40 patients with HF and 55 patients with noncardiac effusions) who had been entered into our computerized database from the periods 2001 to 2004 and 2007 to 2008. In this latter group, the selected patients with

Patients' Characteristics and Distribution of Biomarker Concentrations in Pleural Effusions

We analyzed pleural fluid samples from 90 patients with HF and 91 patients with noncardiac effusions, including 10 hepatic hydrothoraces, 40 malignant effusions, 15 parapneumonic effusions, 11 tuberculous effusions, and 15 miscellaneous exudate effusions (pulmonary embolism, 12 patients; hemothorax, 1 patient; Dressler syndrome, 1 patient; and drug-induced pleural disease, 1 patient). Table 1 lists the characteristics of these two groups. As expected, the patients with HF were of advanced age

Discussion

In this study, three quantitative markers of cardiac stress,4 namely NT-pro-BNP, BNP, and ST2, were measured in pleural fluid, and their concentrations were found to be higher among patients with HF than among those with noncardiac effusions. This is the first report on the use of pleural fluid BNP and ST2 concentrations to determine the cardiac origin of a pleural effusion. On comparing the accuracy of all three tests, the levels of pleural fluid NT-pro-BNP revealed significantly better

Acknowledgments

Author contributions: Conception and design: Drs. Porcel and Esquerda, Ms. Martínez-Alonso. Analysis and interpretation of the data: Ms. Martínez-Alonso and Dr. Bielsa. Drafting of the article: Dr. Porcel. Critical revision of the article for important intellectual content: Drs. Porcel, Cao, Bielsa, Sopena, and Esquerda, and Ms. Martínez-Alonso. Final approval of the article: Drs. Porcel, Cao, Bielsa, Sopena, and Esquerda, and Ms. Martínez-Alonso. Statistical expertise: Ms. Martínez-Alonso.

References (0)

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Funding/Support: Dr. Bielsa is supported by a grant from the Fondo de Investigación Sanitaria (FIS CM07/00020), Instituto de Salud Carlos III, Madrid, Spain.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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