Massive PE is defined as PE associated with sustained hemodynamic instability, whereas submassive PE (sPE) is defined as PE without hemodynamic instability but with abnormal right ventricular (RV) function and/or evidence of myocardial necrosis. It is notable that there is ongoing interest to accurately risk stratify sPE to identify the patients who are at increased risk of decompensating and/or dying. Clinical scores, imaging tests and biomarkers are under investigation, yet an ideal prognostic tool is still pending. A novel cardiac biomarker, heart-type fatty acid-binding protein (h-FABP), is emerging as a significant predictor of mortality in patients with submassive PE.