Value in Pulmonary Embolism
Acute Pulmonary Embolism (PE) is a relatively frequent cardiovascular emergency and a major cause of mortality and morbidity in the general population. International guidelines have proposed that patients presenting with acute PE are classified into “high-risk” and “non-high-risk” groups, with the “high-risk” group being those with hemodynamic instability and should be given immediate thrombolysis or mechanical removal of the thrombus.
However, the treatment strategy of the “non-high-risk” PE patients is less clear and so the risk stratification of this seemingly more stable group represents a real clinical challenge.
A number of recent publications have demonstrated that H-FABP can aid the risk stratification of not only hypotensive high risk PE patients, but also the more diagnostically challenging group of normotensive low-medium risk PE patients.
“H-FABP permits early risk stratification of pulmonary embolism” 13
Puls M, Dellas C, Lankeit M, Olschewski M, Binder L, Geibel A, Reiner C, Schäfer K, Hasenfuss G, Konstantinides S. Eur Heart J. 2007;28(2):224-9.
Puls study in the European Heart Journal from 2007 prospectively evaluated 107 consecutive patients with confirmed PE. The endpoints were (i) PE-related death or major complications and (ii) overall 30-day mortality. They found that 29 patients (27%) had abnormal H-FABP levels at presentation, of which 12 patients had complications. All patients with normal H-FABP had a favourable 30-day outcome.
The study concluded that plasma levels of H-FABP on admission were very reliable predictors of adverse outcome and their prognostic value was superior to that of Troponin and NT-proBNP. There was almost no overlap between patients subsequently suffered major complications and those with an uncomplicated course, with regards to baseline H-FABP levels.
Furthermore, they found that analysis of H-FABP in combination with echocardiography revealed that cardiac ultrasound offered no incremental prognostic information in the presence of a normal H-FABP result.
Prognostic value of H-FABP in hypotensive high-risk patients, compared to Troponin T & NT-proBNPFig 1: Receiver Operating Characteristic (ROC) curves of on admissions levels of H-FABP & NT-proBNP, compared with maximal Troponin levels within the first 24h.
“Elevated H-FABP levels on admission predict an adverse outcome in normotensive patients with acute PE” 14
Dellas C, Puls M, Lankeit M, Schäfer K, Cuny M, Berner M, Hasenfuss G, Konstantinides S. J Am Coll Cardiol. 2010;55(19):2150-7.
Dellas’s study (JACC 2010) was a follow-up project to the Puls et al publication, and attempted to evaluate the predictive value of H-FABP in an even more challenging group of patients – 126 consecutive patients with normotensive low-medium risk PE. Complicated 30-day outcome was defined as death, resuscitation, intubation, or use of catecholamines, and long-term survival was assessed by follow-up clinical examination.
They found that in this low-medium risk group, 9 patients (7%) had complications within 30 days. An elevated H-FABP was associated with an independent 16-fold increased likelihood of death or major complication, as well as being a predictor of long-term mortality. In addition, H-FABP was far more sensitive and specific for predicting 30-day complications and long-term survival than Troponin or NT-proBNP.
These findings are significant as they represent an opportunity for clinicians to not only reduce the number of false positives in this low-medium risk group (e.g. caused by elevated Troponin and/or NT-proBNP), but also to provide reassurance that patients who appear stable and have a negative H-FABP are highly likely to have an excellent prognosis.Fig 2: Prognostic (30-day outcome) sensitivity and specificity of cTnT, NT-proBNP and H-FABP on admission Fig 3: Probability of long-term survival in patients with or without elevation of cTnT, NT-proBNP and H-FABP at dichotomised cut-offs. Red lines = elevated values. Blue lines = normal values.
|Parameter||OR (95% CI)||p Value|
|Heart Rate > 94 beats/min||10.6 (1.3-87.2)||0.029|
|H-FABP > 6 ng/ml||36.6 (4.3-3.08)||0.001|
|cTnT > 0.04 ng/ml||3.3 (0.4-13.1)||0.087|
|RV dysfunction (echocardiography)||2.8 (0.6-12.3)||0.178|