Pulmonary · Topic 15 of 28

Pulmonary Embolism

Pulmonary · venous thromboembolism

Pulmonary Embolism

Probability first, then D-dimer or CT angiography. Anticoagulate on strong suspicion; hypotension from PE means clot-busting therapy now.

Key numbers

Age-adjusted D-dimer when PE is unlikelyage × 10 ng/mL (> 50 y)

Massive PE: give systemic thrombolysisSBP < 90 mmHg ≥ 15 min

01 · The ruleAge-adjusted D-dimer when PE is unlikely

Estimate pretest probability (Wells, Geneva, YEARS). If PE is unlikely (Wells ≤ 4) or probability is low–intermediate, a normal D-dimer excludes PE — use an age-adjusted cutoff (age × 10 ng/mL) after age 50.

02 · DoCT pulmonary angiography confirms PE

With high pretest probability or a positive D-dimer, order CT pulmonary angiography — the imaging test of choice; use a V/Q scan when iodinated contrast is contraindicated (eg, renal insufficiency).

03 · DoMassive PE: give systemic thrombolysis

High-risk (massive) PE = SBP < 90 mmHg or a fall of ≥ 40 mmHg for 15 minutes, or vasopressor need. Give systemic thrombolysis (alteplase 100 mg IV over 2 hours) unless contraindicated.

Presentation

What you'll see

ECG: sinus tachycardia; S1Q3T3 is uncommonThe ECG usually shows only sinus tachycardia and nonspecific ST–T changes; S1Q3T3 or new RBBB (about 5%) and V1–V4 T inversion suggest RV strain. The chest x-ray is usually nonspecific.

Diagnosis & monitoring

Work-up

PERC rule: no testing if all 8 negativeLow clinical risk plus all 8 PERC criteria = no PE testing: age < 50, HR < 100, SpO₂ ≥ 95%, no hemoptysis, estrogen, prior VTE, unilateral leg swelling, or recent surgery/trauma.

Submassive PE: RV strain without hypotensionIntermediate-risk (submassive) PE = RV dilation or hypokinesis on CT or echo, or raised troponin/BNP, with normal blood pressure. Anticoagulate and monitor for deterioration; routine systemic thrombolysis is not recommended (bleeding harm).

2026 AHA/ACC PE categories A to E2026 AHA/ACC categories: A subclinical (incidental), B symptomatic, low severity score, C elevated severity (biomarkers or RV dysfunction), D transient hypotension or normotensive shock, E cardiopulmonary failure (E1 persistent hypotension, E2 refractory shock/arrest).

Do right now

In this order

First moves

Anticoagulate on strong suspicion, before imaging

→

CT pulmonary angiography confirms PE

→

Support the failing RV: cautious fluid, norepinephrine

→

Massive PE: give systemic thrombolysisSBP < 90 mmHg ≥ 15 min

Why each step

Anticoagulate on strong suspicion, before imagingStart anticoagulation as soon as PE is strongly suspected if bleeding risk is low — do not wait for the CT; reaching therapeutic anticoagulation within 24 hours lowers in-hospital and 30-day mortality.

CT pulmonary angiography confirms PEWith high pretest probability or a positive D-dimer, order CT pulmonary angiography — the imaging test of choice; use a V/Q scan when iodinated contrast is contraindicated (eg, renal insufficiency).

Support the failing RV: cautious fluid, norepinephrineIn PE with shock, give only small fluid boluses (volume overload worsens the failing RV), start norepinephrine first, add dobutamine or milrinone for low output, and avoid intubation and deep sedation when possible.

Massive PE: give systemic thrombolysisHigh-risk (massive) PE = SBP < 90 mmHg or a fall of ≥ 40 mmHg for 15 minutes, or vasopressor need. Give systemic thrombolysis (alteplase 100 mg IV over 2 hours) unless contraindicated.

Management

Orders

DOAC over warfarin; LMWH over heparin drip must knowFor oral therapy, prefer a DOAC (apixaban, rivaroxaban, edoxaban, dabigatran) over warfarin; when parenteral therapy is needed, LMWH is recommended over unfractionated heparin for most patients.

Low-severity PE can go home on a DOACUse sPESI, PESI or Hestia to find low-risk patients: categories A–B can be discharged early on a DOAC with structured follow-up; categories C–E are hospitalized.

Catheter or surgical embolectomy if lysis is barredIf thrombolysis is contraindicated or fails, use catheter-directed therapy (thrombolysis or suction thrombectomy) or surgical embolectomy; VA-ECMO can bridge refractory shock. A PE response team speeds these decisions.

Reserve the heparin drip for few patientsLMWH is preferred even in categories C–E. Use IV UFH (aPTT 1.5–2.5 × control; reversible with protamine) for refractory shock or arrest when VA-ECMO is considered (category E2) or when CrCl is below 30 mL/min.

Edoxaban and dabigatran need heparin lead-inApixaban and rivaroxaban can be started alone; edoxaban and dabigatran require 5–10 days of parenteral anticoagulation first. Warfarin overlaps heparin ≥ 5 days and until INR 2–3 for 24 hours.

IVC filter only if anticoagulation impossiblePlace a retrievable IVC filter only when anticoagulation is contraindicated or PE recurs despite therapeutic anticoagulation — it does not replace anticoagulation.

Red flags & don'ts

Avoid harm

Absolute bars to thrombolysis in PE avoidAbsolute contraindications to systemic thrombolysis: prior hemorrhagic stroke, ischemic stroke within 6 months, intracranial tumor, recent major trauma, surgery or head injury, active bleeding. In imminent death from PE, only intracranial hemorrhage is absolute.

Pregnancy: LMWH, not DOACs avoidDOACs are not used in pregnancy or breastfeeding; treat PE with LMWH (or unfractionated heparin).

The rules

Know these

Anticoagulate 3 months if provoked by transient factorTreat at least 3 months; stop then if PE was provoked by a major transient risk factor (surgery, trauma, immobilization). Unprovoked PE or a persistent risk factor warrants extended anticoagulation if bleeding risk allows.

High-risk or intermediate-risk PE?

Commonly confused

Blood pressure	SBP < 90 mmHg for 15 min, or on vasopressors
Right ventricle	Failing, causing shock
Troponin / BNP	Often high
Treatment	Anticoagulation plus systemic thrombolysis or embolectomy
2026 AHA/ACC category	E (E1 persistent hypotension; E2 refractory shock or arrest)

Commonly confused

Tell apart

Negative leg ultrasound does not exclude PEA negative leg duplex never excludes PE, but a positive one in a stable patient who cannot have CT contrast justifies anticoagulation without lung imaging.

More detail

Reference

Show 5 reference facts

Chronic thromboembolic pulmonary hypertension follows 1–3% of PEs; ask about dyspnea at every visit for a year and evaluate (V/Q scan, echo) if symptoms persist after 3 months of anticoagulation.

Echo supports risk stratification, not diagnosis: RV dilation, McConnell sign (RV free-wall hypokinesis with apical sparing) and the 60/60 sign suggest acute PE; echo should not be used to confirm or exclude it.

Cancer-associated PE: apixaban, edoxaban or rivaroxaban are now recommended over LMWH. Suspected HIT: switch to argatroban or fondaparinux.

Thrombophilia testing is not routine; consider it for unprovoked PE in younger patients, recurrent PE or a strong family history — antiphospholipid syndrome changes the anticoagulant choice.

Most PE deaths occur within 1 hour of presentation; in-hospital mortality is about 8% in stable patients, 25% with cardiogenic shock and 65% when CPR is needed.

Pearl

Unexplained tachycardia, tachypnea or hypoxemia is PE until proven otherwise — and a normal leg ultrasound does not clear the lungs.

Sources · Merck Manual Professional — Pulmonary Embolism (PE) · Creager MA et al. 2026 AHA/ACC/ACCP/ACEP/CHEST/SCAI/SHM/SIR/SVM/SVN Guideline for the Evaluation and Management of Acute Pulmonary Embolism in Adults. Circulation 2026 · ACC press release (Feb 19, 2026) — First AHA/ACC acute pulmonary embolism guideline · emDocs — 2026 Guideline: Evaluation and Management of Acute PE (summary of the AHA/ACC guideline) · DailyMed — Activase (alteplase) prescribing information · MDCalc — Wells' Criteria for Pulmonary Embolism · Can VA-ECMO Be Used as an Adequate Treatment in Massive Pulmonary Embolism? (2021; lists the 2019 ESC absolute contraindications to fibrinolysis) · LITFL — Goodbye "Massive" and "Submassive" (2026 AHA/ACC PE categories A–E) · CHEST Physician — Navigating PE treatment: what the AHA/ACC guidelines recommend · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).