Q: How to define submassive PE?

Answer: Acute PE without systemic hypotension (systolic blood pressure ≥90 mm Hg) but with either RV dysfunction or myocardial necrosis.

1. RV dysfunction means the presence of at least 1 of the following:

• RV dilation (apical 4-chamber RV diameter divided by LV diameter >0.9) or RV systolic dysfunction on echocardiography
• RV dilation (4-chamber RV diameter divided by LV diameter >0.9) on CT
• Elevation of BNP (>90 pg/mL)
• Elevation of N-terminal pro-BNP (>500 pg/mL); or
• Electrocardiographic changes (new complete or incomplete right bundle-branch block, anteroseptal ST elevation or depression, or anteroseptal T-wave inversion)

2. Myocardial necrosis is defined as either of the following:

• Elevation of troponin I (>0.4 ng/mL) or
• Elevation of troponin T (>0.1 ng/mL)

Reference:

Management of Massive and Submassive Pulmonary Embolism, Iliofemoral Deep Vein Thrombosis, and Chronic Thromboembolic Pulmonary Hypertension - A Scientific Statement From the American Heart Association - Circulation. 2011; 123: 1788-1830