N-terminal prohormone of brain natriuretic peptide: a useful tool for the detection of acute pulmonary artery embolism in post-surgical patients.

BACKGROUND Acute pulmonary embolism (APE) is an important clinical problem in patients after major surgery and often remains a difficult diagnosis because of unspecific clinical symptoms. Therefore, we investigated the role of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) for the detection of APE. METHODS In 44 patients with suspected APE referred to the intensive care unit after major surgery, serum NT-proBNP, troponin-I, and D-dimers were measured according to the standard hospital protocol. To definitively confirm or exclude APE, all patients underwent an angiographic CT scan of the thorax. RESULTS APE was confirmed in 28 and excluded in 16 patients by CT scan. NT-proBNP was significantly (P<0.01) higher in patients with APE [4425 (sd 8826; range 63-35 000) pg ml(-1)] compared with those without [283 (sd 327; range 13-1133) pg ml(-1)]. The sensitivity of the NT-proBNP screening was 93%, specificity 63%, positive predictive value 81%, and negative predictive value 83%. There were no significant (P = 0.96) differences in D-dimers between subjects with and without APE [confirmed APE: 511 (sd 207; range 83-750) μg litre(-1); excluded APE: 509 (sd 170; range 230-750) μg litre(-1)]. Troponin-I levels were not elevated in 32% of the patients with APE. CONCLUSIONS D-dimer levels are frequently elevated in post-surgical patients and not applicable for confirmation or exclusion of APE. In contrast, NT-proBNP appears to be a useful biomarker for APE diagnosis in the postoperative setting. In the case of NT-proBNP levels below the upper reference limit, haemodynamically relevant APE is unlikely. Troponin-I in contrast is not considered to be helpful.