Previous trials have investigated the use of B-type natriuretic peptide (BNP) to assess patients with dyspnea in the ED. The sentinel trial was the BNP (Breathe Not Properly) trial that evaluated nearly 800 patients presenting to the ED with complaints of dyspnea. The investigators found that a B-type natriuretic peptide of 100 pg/mL or higher had a sensitivity of 90 percent, a specificity of 76 percent, and an accuracy of 83 percent for differentiating congestive heart failure from other causes of dyspnea. In addition, a BNP of 50 pg/mL or less had a negative predictive value of 96 percent to exclude CHF.1
The American College of Emergency Physicians (ACEP) proposed guidelines for the use of natriuretic peptides, BNP and NT-pro-BNP for the assessment of patients with possible CHF in the ED. The ACEP guidelines proposed that a BNP level less than 100 pg/dL or an NT-proBNP level less than 300 pg/dL could help to rule out CHF and a BNP level of 500 pg/dL or more or an NT-proBNP level of 1000 pg/dL or more supports the diagnosis of CHF as the cause of dyspnea.2
Now, a new industry-sponsored trial, researchers pooled data from 453 patients enrolled in two previous ED-based studies, PRIDE and BIONICS-HF, to see if serum procalcitonin levels could help to differentiate patients with pneumonia from those with CHF.3
The final diagnosis was acutely decompensated HF in 212 patients (47%), pneumonia in 30 (6.5%), and both HF and pneumonia in another 30 (6.5%). The median procalcitonin level was significantly higher in patients with pneumonia than in those without pneumonia (0.38 ng/mL vs. 0.06 ng/mL). Among patients who had a high clinical likelihood of HF, a procalcitonin cutoff value of 0.10 ng/mL had a sensitivity for identifying pneumonia of 95% and a negative predictive value (NPV) of 99%. For patients with a low likelihood of HF, a procalcitonin cutoff value of 0.1 ng/mL had a specificity of 85% and a NPV of 95%.
This study provides some initial data that procalcitonin levels can help with a clinical assessment and natriuretic peptide levels to assess whether patients have CHF or bacterial pneumonia as the cause of dyspnea. I specify bacterial pneumonia because procalcitonin levels generally remain low in viral pneumonias like influenza.
2. Silvers SM et al. Clinical policy: critical issues in the evaluation and management of adult patients presenting to the emergency department with acute heart failure syndromes. Ann Emerg Med. 2007; 49: 627–669.