Intermediate-risk pulmonary embolism (PE)—formerly called “submassive” PE—occurs when a patient is hemodynamically stable (normal blood pressure) but shows signs of right ventricular (RV) strain or heart stress.
Normotensive: Systolic blood pressure remains at or above 90 mmHg without immediate collapse.
RV Dysfunction: Imaging, echocardiogram or CT scan shows an enlarged or overworked right side of the heart.
Elevated Biomarkers: Blood tests show high levels of cardiac injury markers like troponin or heart failure markers like BNP/NT-proBNP.
Intermediate-Low Risk: Only one of these indicators (RV strain or elevated biomarkers) is abnormal.
Intermediate-High Risk: Both RV strain and elevated biomarkers are abnormal, indicating a higher chance of sudden clinical worsening.
Management and Treatment
Anticoagulation: Immediate therapeutic blood thinners (such as low molecular weight heparin or direct oral anticoagulants) are the standard baseline treatment for all stable patients.
Close Monitoring: Patients are watched closely for signs of decompensation, such as dropping blood pressure, rising heart rate, or worsening shortness of breath.
Advanced Reperfusion: For patients showing signs of clinical deterioration or severe intermediate-high risk features, advanced procedures like catheter-directed therapy (CDT) or mechanical thrombectomy may be considered.
2026 AHA/ACC/Multisociety guideline scheme, most patients formerly labeled “intermediate-risk” fall into Category C — symptomatic PE with an elevated clinical severity score subdivided by cardiopulmonary dysfunction:
C1 — normal RV size/function and normal biomarkers (troponin I/T, BNP)
C2 — abnormal RV or ≥1 abnormal biomarker
C3 — abnormal RV and ≥1 abnormal biomarker
A respiratory modifier (R) is appended when hypoxemia, tachypnea, or a need for supplemental oxygen is present.
More severe presentations — normotensive (“preshock”) shock or transient/relative hypotension responsive to volume — are captured separately as Category D (incipient cardiopulmonary failure), distinguishing them from truly stable disease.
The traditional definition of intermediate-risk (submassive) PE is RV strain without hypotension — RV dysfunction on echocardiography or CTPA (RV/LV ratio >0.9) and/or elevated cardiac biomarkers (troponin, BNP/NT-proBNP) in a normotensive patient.
Intermediate–high risk: both RV dysfunction on imaging AND positive troponin.
Intermediate–low risk: one or neither of RV dysfunction/positive troponin.
This group is common (roughly 35–67% of PE presentations) with a wide reported 90-day mortality of ~3–15%, higher in observational cohorts than in RCTs
Management centers on anticoagulation plus close monitoring. For intermediate-risk PE, therapeutic anticoagulation with monitoring — not routine systemic thrombolysis — is the standard, reserving reperfusion for the roughly 1 in 20 patients who hemodynamically decompensate.
Systemic thrombolysis is not routinely recommended. In the PEITHO trial, adding tenecteplase to heparin reduced hemodynamic decompensation by ~3 percentage points but increased major bleeding by ~9 points and hemorrhagic stroke by ~2 points.
Low-molecular-weight heparin is the preferred initial anticoagulant, unfractionated heparin causes excess bleeding, and immediate DOAC use vs LMWH has not been specifically studied in this population.
Catheter-directed thrombolysis is an option for intermediate-risk patients with proximal/central clot, but evidence is insufficient to favor it over LMWH; it remains an active area of investigation.
Escalate to reperfusion (systemic thrombolysis, catheter-directed therapy, or embolectomy) if the patient decompensates toward high-risk (hemodynamic instability).
The intermediate–high (Category C3) subgroup — both RV dysfunction and positive troponin — warrants the closest monitoring for decompensation and consideration of rescue reperfusion.
The Bova score further refines 30-day complication risk in normotensive patients using systolic BP, troponin, RV dysfunction, and heart rate.