Internal Medicine & Pulmonology & Emergency Medicine
Pulmonary embolism
Pulmonary embolism (PE) is the acute obstruction of one or more pulmonary arteries by thrombotic material - in over 90 % of cases, a thrombus originating from deep vein thrombosis (DVT) of the lower limbs or pelvis. Together with DVT, it constitutes the two clinical manifestations of venous thromboembolism (VTE), a unified pathophysiological entity. PE is the third leading cause of cardiovascular mortality after myocardial infarction and stroke, with an estimated incidence of 60 to 70 cases per 100,000 inhabitants per year. Short-term mortality varies considerably according to severity: less than 1 % for low-risk PE treated early, reaching 30 to 50 % for untreated massive PE with cardiogenic shock. The pathophysiology is based on Virchow's triad - venous stasis, hypercoagulability, endothelial damage - and the resulting pulmonary arterial obstruction leads to increased pulmonary vascular resistance → right ventricular (RV) dilatation and dysfunction → reduced cardiac output → hypoxemia by shunt effect and increased ventilatory dead space → shock state if obstruction is massive. Risk stratification on admission - distinguishing between high-risk PE (shock or hypotension), intermediate-risk (VD dysfunction without shock) and low-risk - is fundamental, as it determines the urgency and intensity of treatment.
Clinical presentation, risk factors, and diagnostic approach
- Clinical Presentation — From Common Syndrome to Life-Threatening Emergency: dyspnée brutale inexpliquée (symptôme le plus fréquent — 80 % des EP) ; douleur thoracique pleurale (pleurésie réactionnelle — infarctus pulmonaire périphérique — 50 % des EP) ; tachycardie sinusale (>100 bpm — signe physique le plus fréquent) ; hémoptysie (infarctus pulmonaire hémorragique — 10–15 %) ; syncope ou pré-syncope (EP massive — dysfonction VD aiguë — 10 %) ; signes de TVP concomitante (douleur + œdème unilatéral du mollet — 30 % des EP) ; formes insidieuses : dyspnée d'effort progressive, tachycardie inexpliquée, exacerbation d'insuffisance cardiaque ou de BPCO — EP doit être évoquée dans tout tableau cardiorespiratoire inexpliqué
- Key risk factors: recent major surgery<3 mois — surtout orthopédique : prothèse totale de hanche ou genou risque × 40–60 sans prophylaxie) ; immobilisation prolongée (alitement>3 days, air travel >8h, limb paralysis); active cancer (paraneoplastic hypercoagulability — risk × 4–6 — 20 % of PE have underlying cancer); pregnancy and postpartum (risk × 4–5 — PE is the leading cause of direct maternal mortality in Canada); combined oral contraceptives (risk × 3–4 — especially if smoking + obesity); history of VTE (risk of recurrence: 10 % at 1 year, 30 % at 5 years); inherited (Factor V Leiden, prothrombin G20210A mutation, protein C/S deficiency, antithrombin deficiency) or acquired (antiphospholipid syndrome) thrombophilia; obesity (BMI >30); chronic heart or respiratory failure; central venous catheter
- Wells Score and Pretest Probability Stratification: Clinical signs of DVT (3 pts) + PE more probable than alternative diagnosis (3 pts) + heart rate >100 bpm (1.5 pts) + immobilization or surgery within 4 weeks (1.5 pts) + history of DVT/PE (1.5 pts) + hemoptysis (1 pt) + active cancer (1 pt); score <2 >6 = High probability; PERC Rule (Pulmonary Embolism Rule-out Criteria): If all 8 PERC criteria are negative in a patient with low pretest probability → PE ruled out without D-dimer testing (age (<50 years old + HR <100 bpm + SpO₂ ≥95% % + no DVT + no hemoptysis + no recent estrogen use + no history of DVT/PE + no recent surgery or trauma requiring hospitalization)
- Diagnostic workup : D-dimers (high-sensitivity ELISA): reference value <500 µgl — valeur prédictive négative>99 % if pretest probability low or moderate → D-dimer negative = PE excluded; age-adjusted threshold: in >50 years, use age × 10 µg/L as threshold (reduces false positives without loss of sensitivity - Douma 2010 BMJ); D-dimer positive or high probability → thoracic angioscanner (AngioTDM): gold standard - sensitivity 83-100 %, specificity 89-98 % - visualizes clots down to segmental arteries; V/Q lung scintigraphy (ventilation/perfusion): alternative to AngioCT if IC to iodine (allergy, severe CKD) + in pregnant women (less breast irradiation) + if suspected chronic post-embolic pulmonary hypertension (CEPH); lower limb venous ultrasound (proximal DVT): useful adjunct if AngioCT is inconclusive; ECG: sinus tachycardia (most frequent sign) + S1Q3T3 (15 % - not very specific) + incomplete BBD + T-wave inversion in V1-V4 (VD overload); echocardiography (ETT): assessment of VD function (dilatation + hypokinesia + McConnell sign) + PAPS estimation + search for thrombus in situ + hemodynamic status → indispensable in high-risk PEs
Treatment
| Treatment | Mechanism, scheme and procedures | Duration, effectiveness and precautions |
|---|---|---|
| Anticoagulation — treatment of reference Acute Coronary Occlusive Disease (ACOD) first line - heparin if high risk or pregnancy |
Direct oral anticoagulants (DOACs) - 1st-line treatment ESC 2019 / Thrombosis Canada for non-massive PE: rivaroxaban (Xarelto) 15 mg × 2/d × 21 days then 20 mg × 1/d (high initial dose regimen without prior heparin); apixaban (Eliquis) 10 mg × 2/d × 7 days then 5 mg × 2/d (same principle - without prior heparin) ; dabigatran (Pradaxa) 150 mg × 2/d after 5-10 days of initial heparin; edoxaban (Lixiana) 60 mg × 1/d after 5-10 days of initial heparin; low-molecular-weight heparin (LMWH) + antivitamin K (warfarin) : conventional treatment always used if ACOD contraindicated (severe CKD eGFR <30 + active cancer + pregnancy + antiphospholipid syndrome) - LMWH: enoxaparin (Lovenox) 1 mg/kg SC × 2/d or 1.5 mg/kg × 1/d; tinzaparin 175 IU/kg × 1/d - warfarin : target INR 2-3 - LMWH + warfarin overlap up to 2 consecutive INR ≥2 24h apart; unfractionated heparin (UFH) IV: indicated if high-risk PE or severe IR - bolus 80 IU/kg + continuous infusion 18 IU/kg/h - target aPTT 60-100 sec (1.5-2.5 × control) | ACODs are superior to warfarin for PE (40-50 % reduction in bleeding risk with non-inferior anticoagulant efficacy - van Es 2014 Lancet Haematol meta-analysis); contraindications to ACODs: eGFR <15-30 ml/min (depending on molecule) + pregnancy + breastfeeding + antiphospholipid syndrome (IgG and IgM positive - increased risk of recurrence with ACOD vs warfarin - ESC/ISTH recommendation) + active cancer (LMWH or rivaroxaban/apixaban according to the CARAVAGGIO/SELECT-D study); reversibility: andexanet alfa (Andexxa) for rivaroxaban/apixaban + idarucizumab (Praxbind) for dabigatran - available in hospital centers for major bleeding; duration of anticoagulation depending on context: PE provoked by major reversible transient factor (surgery, immobilization) → 3 months; unprovoked PE (idiopathic) → minimum 3 months then reassessment of risk of recurrence vs. hemorrhage; PE on active cancer → indefinite duration as long as cancer is active |
| Systemic thrombolysis Massive pulmonary embolism with shock — life-threatening emergency |
Formal indication: high-risk PE with cardiac arrest + hemodynamic instability (PAS 15 min not otherwise explained + cardiogenic shock with signs of organ failure); agent: alteplase (tPA - Activase) 100 mg IV over 2 hours (10 mg bolus IV over 1-2 min + 90 mg IV over 2h) - ESC 2019 reference protocol; in case of cardiac arrest: alteplase 50 mg bolus IV + external cardiac massage for at least 90 min (lyses thrombus during resuscitation); absolute contraindications: hemorrhagic stroke or ischemic stroke <3 months + recent intracranial or spinal surgery + recent severe head trauma + active non-compressible bleeding; relative contraindications (to be weighed against vital risk): major surgery <3 weeks + recent gastrointestinal bleeding <1 month + pregnancy + thrombocytopenia 180/110); after thrombolysis: resume bolus-free IV UFH anticoagulation as soon as infusion ends (aPTT <80 sec before resuming) or as soon as aPTT <2 × control if infusion stopped | Systemic thrombolysis reduces mortality by 50–60% %in massive PE with shock (Marti 2015 meta-analysis — NNT ≈ 8 to prevent one death) at the cost of a major hemorrhagic risk of 10–20% % (hemorrhagic stroke 1–3% %); in intermediate-high risk PE (RV dysfunction + elevated troponin) without shock — rescue thrombolysis: reserved for hemodynamic deterioration under anticoagulation alone (PEITHO trial 2014 — reduction in early complications but excess of hemorrhagic strokes with systematic thrombolysis); reduced dose thrombolysis («low dose»): alteplase 50 mg over 2h (MOPETT study 2013 — submassive PE — reduction in PAPS and HPEC at 28 months — limited data); the decision to thrombolyze in intermediate PE must be individualized — emergency physician/intensivist/pulmonologist consultation. |
| Surgical embolectomy and catheter-directed Alternatives to systemic thrombolysis |
Surgical embolectomy under CEC : indication if thrombolysis contraindicated or failure + massive PE with shock + right heart in situ thrombus + patent foramen ovale with paradoxical emboli - emergency cardiothoracic surgery + extracorporeal circulation (ECS) + pulmonary artery thrombus extraction - success rate 80-90 % in expert centers - operative mortality 20-30 % (versus >50 % without treatment); catheter-directed thrombolysis (EKOS + CDT): multiperforated catheter positioned in the pulmonary artery percutaneously (femoral vein → OD → AP) - local infusion of low-dose alteplase (1 mg/h/catheter × 12-24h) ± low-frequency ultrasound (EKOS system - ULTIMA trial 2014 - SEATTLE II 2015 - PAPmoy reduction + improvement in LV/GV ratio at 24h without excess bleeding vs. systemic thrombolysis); catheter-directed thrombus aspiration (Penumbra Indigo, AngioVac): option less well evaluated - specialized centers; vena cava filters (filter in inferior vena cava): indicated if PE confirmed + anticoagulation formally contraindicated (major active hemorrhage) or recurrence of PE under optimal anticoagulation - retrievable filters preferred to permanent ones - withdrawal as soon as anticoagulation is possible | PERT (Pulmonary Embolism Response Teams) interdisciplinary teams—available at several Quebec university hospitals (CHUM, MUHC, IUCPQ)—allow for rapid, collaborative decision-making (ER physician + pulmonologist + hematologist + cardiologist + vascular surgeon) for high-risk and high-intermediate risk PEs. Their implementation is associated with a reduction in in-hospital mortality in several cohorts. Permanent vena cava filters increase the long-term risk of DVT (Decousus PREPIC trial 1998) and are not a substitute for anticoagulation. Their indication should be reassessed regularly with removal if possible. CPAP and non-invasive ventilation can worsen the hemodynamic status in massive PE (increased RV afterload). Prefer high-flow O₂ or orotracheal intubation with protective settings (avoid high pressures). |
| Duration of anticoagulation and prevention of recurrence Individualized decision — bleeding benefit/risk balance |
Decision algorithm according to context: EP provoked by major surgical transient factor (surgery ≥30 min + general anesthesia + bed rest >3 days) → stop at 3 months - low risk of recurrence (3 % at 5 years); EP provoked by minor transient factor (travel, brief immobilization, contraceptives) → 3 months - intermediate risk (15 % at 5 years) ; unprovoked PE (idiopathic - no identified triggering factor) → minimum 3 months then assessment of benefit/risk ratio of prolongation - HERDOO2 score in women (hyperpigmentation + edema + redness of lower limb + post-anticoagulation D-dimers + obesity + age ≥65 years) - HAS-BLED score for bleeding risk - ESC recommendation: indefinite prolonged anticoagulation if low bleeding risk + unprovoked first episode + no contraindication; PE on active cancer → LMWH or apixaban/rivaroxaban (CARAVAGGIO 2020 - HOKUSAI VTE Cancer) as long as cancer active or treated; major thrombophilia (antiphospholipid, antithrombin deficiency) → indefinite anticoagulation; recurrent PE → indefinite anticoagulation except major bleeding risk | Unprovoked PE recurs in 30–50 % cases at 10 years without prolonged anticoagulation — the decision to stop anticoagulation at 3 months should be made in consultation with the patient (preferences + individual bleeding risk + quality of life on anticoagulation); reduced dose after 6 months: apixaban 2.5 mg × 2/day (AMPLIFY-EXT trial — 67 % reduction in recurrences vs placebo) or rivaroxaban 10 mg × 1/day (EINSTEIN CHOICE — 74 % reduction vs aspirin) — options for indefinite prolongation at lower bleeding risk; aspirin alone (100 mg × 1/day) is insufficient to prevent PE recurrences (only 30 % reduction — ASPIRE/WARFASA) vs reduced-dose DOACs — do not use aspirin as an alternative to anticoagulants; D-dimer levels post-anticoagulation (1 month after stopping): positive D-dimers → doubled recurrence risk → strong argument for prolonging anticoagulation (DOLORES/PROLONG study) |
| Outpatient management and post-embolic pulmonary hypertension Low-risk EP — long-term sequelae |
Outpatient treatment or early discharge of low-risk PE: simplified PESI (Pulmonary Embolism Severity Index) score = 0 (age <80 + no cancer + HR <110 + PAS ≥100 + SpO₂ ≥90 % + no heart failure or COPD) → low-risk PE → outpatient treatment possible + ACOD straightaway; Hestia criteria (12 exclusion criteria for outpatient treatment) - if all negative → discharge possible; recurrence and 30-day mortality rate of outpatient treatment of low-risk PE: 25 mmHg on right catheterization) - incidence: 0.5-3.8 % of PEs at 2 years; presentation: progressive exertional dyspnea + exercise intolerance + signs of chronic pulmonary heart disease; diagnosis: V/Q scintigraphy (first step - high sensitivity) + CT angiography + pulmonary catheterization; gold standard surgical treatment: pulmonary endarterectomy (PEA) - Jamieson operation - expert centers (Toronto General Hospital - best Canadian center) + riociguat (Adempas - soluble guanylate cyclase stimulator) if inoperable or residual HPTEC post-EAP | CTEPH is underdiagnosed — all patients with PE and persistent dyspnea >3 months on optimal anticoagulation should undergo screening V/Q scan; PEA is curative in 70–80 % of operable cases (normalization of pulmonary pressures) — operative mortality 2–5 % in expert centers; riociguat (Adempas) is the only Health Canada-approved drug treatment for inoperable CTEPH — reimbursed RAMQ under conditions; cardiopulmonary rehabilitation after PE is recommended for patients with persistent deconditioning or CTEPH — improves functional capacity and quality of life; 6MWT (6-minute walk test) + echocardiography + NT-proBNP: follow-up assessments at 3 and 6 months after PE to screen for CTEPH and assess RV recovery |
ℹ️
Thrombophilia workup — when to prescribe: A thrombophilia workup (Factor V Leiden, prothrombin G20210A mutation, protein C, protein S, antithrombin, antiphospholipid antibodies—lupus anticoagulant + anticardiolipin IgG/IgM + anti-beta2-GP1) is recommended in cases of unprovoked PE before age 50, a first-degree family history of VTE, recurrent PE or DVT, thrombosis in an unusual site (mesenteric, caval, cerebral veins), or suspected antiphospholipid syndrome. It should be performed at least 3 months after the acute event and at a distance from anticoagulation (warfarin falsely alters protein C and S levels; DOACs can interfere with some functional coagulation tests). A positive result modifies the duration of anticoagulation but should not delay treatment of the acute event.
Emergency — Massive pulmonary embolism and shock
Dial 911 immediately if: Severe sudden shortness of breath + chest pain + SpO₂ 120 bpm pulmonary embolism until proven otherwise — transfer to ER.
Hypotension (SBP < 90 mmHg) + syncope + signs of shock (pallor, mottling, altered consciousness) in this context → massive PE → emergency thrombolysis or surgical embolectomy for life-threatening condition — high-flow O₂ + IV access + call for resuscitation team.
Patient known for anticoagulation for PE with sudden respiratory worsening → Embolic recurrence or bleeding on anticoagulation - urgent evaluation.
Consult at Clinique Omicron
Clinique Omicron physicians evaluate patients with symptoms suggestive of pulmonary embolism (unexplained shortness of breath, chest pain, tachycardia), apply validated diagnostic algorithms (Wells score, D-dimers, CT angiography referral), initiate anticoagulation, and provide outpatient follow-up for low-risk pulmonary embolisms treated at home. Post-pulmonary embolism follow-up, including monitoring for chronic thromboembolic pulmonary hypertension and determining optimal anticoagulation duration, is coordinated with pulmonology and internal medicine teams. Consultations are available at our service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not substitute the advice of a qualified healthcare professional. Any suspicion of pulmonary embolism constitutes a medical emergency requiring immediate hospital evaluation.
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