Pulmonary Embolism

Details

Acute pulmonary embolism (PE) is obstruction of the pulmonary arterial circulation by thrombus, usually arising from deep vein thrombosis (DVT) of the lower extremities. PE spans a broad clinical spectrum — from asymptomatic incidental findings to cardiogenic shock and cardiac arrest — determined primarily by the degree of right ventricular (RV) pressure overload. It is the third most common acute cardiovascular syndrome after myocardial infarction and stroke. The 2026 AHA/ACC multi-society guideline introduced the AHA/ACC Acute PE Clinical Categories (A–E) as a unified severity classification to guide all management decisions.

Key Facts

Diagnosis

Clinical Pre-Test Probability

• Wells score: Low <2, Moderate 2–6, High >6 (standard); PE likely >4, unlikely ≤4 (modified). Key variables: DVT symptoms (+3), PE most likely diagnosis (+3), HR >100 (+1.5), immobilisation ≥3 days or surgery within 4 weeks (+1.5), prior DVT/PE (+1.5), haemoptysis (+1), cancer (+1). (sources/acute-pe-aha-2026, rating: very high)
• Revised Geneva Score: Age >65, prior DVT/PE, surgery/fracture within 1 month, active cancer, unilateral lower-limb pain, haemoptysis, HR 75–94 bpm or ≥95 bpm, pain on lower-limb palpation and unilateral oedema. (sources/acute-pe-aha-2026, rating: very high)
• PERC Rule: 8 criteria (age <50, HR <100, O₂ sat ≥95%, no haemoptysis, no oestrogen use, no prior DVT/PE, no unilateral leg swelling, no recent surgery/trauma); if ALL met with clinical pretest probability <15%, PE excluded without testing. (sources/acute-pe-aha-2026, rating: very high)

D-Dimer

• Standard threshold 500 μg/L (FEU); age-adjusted threshold = age × 10 μg/L for patients >50 years — safely excludes PE with <2% missed VTE at 3 months in low/intermediate pretest probability (COR 2a/B-R). (sources/acute-pe-aha-2026, rating: very high)
• YEARS algorithm: D-dimer threshold 500 μg/L if ≥1 criterion (clinical DVT signs, haemoptysis, PE most likely diagnosis); 1000 μg/L if no criteria. Lower failure rate and higher efficiency than age-adjusted D-dimer alone (COR 2a/B-R). (sources/acute-pe-aha-2026, rating: very high)
• Pregnancy-adapted YEARS criteria reduce CTPA exposure by 65% in first trimester (COR 2b/B-NR). (sources/acute-pe-aha-2026, rating: very high)

Imaging

• CTPA: Standard modality (COR 1/B-R); wide availability, excellent diagnostic performance, allows RV assessment and alternative diagnosis identification. Preferred over V/Q scan. (sources/acute-pe-aha-2026, rating: very high)
• V/Q SPECT: Preferred over planar V/Q (COR 2a/B-R); greater reproducibility, specificity, lower radiation. Suitable alternative when CTPA contraindicated. (sources/acute-pe-aha-2026, rating: very high)
• Echocardiography: NOT useful for confirming or excluding PE diagnosis (COR 3:No Benefit); sensitivity limited; used for RV dysfunction risk stratification only. (sources/acute-pe-aha-2026, rating: very high)
• On CTPA: report numerical RV/LV ratio (cut-point ≥1.0: sensitivity 85%, specificity 72%); COR 1 recommendation (COR 1/B-R). (sources/acute-pe-aha-2026, rating: very high)
• On TTE: report RV/LV end-diastolic ratio, TAPSE (<1.6 cm = abnormal), estimated RVSP, McConnell's sign, tricuspid systolic velocity (>2.6 m/s), paradoxical septal motion, IVC respirophasic collapse (COR 1/B-NR). (sources/acute-pe-aha-2026, rating: very high)

Risk Stratification — AHA/ACC Acute PE Clinical Categories (2026)

See detailed framework in concepts/Acute-PE-Clinical-Categories.

• Respiratory modifier (R): added when high O₂ requirement, high RR, or NIV/invasive ventilation needed. (sources/acute-pe-aha-2026, rating: very high)

Biomarkers

• Troponin (I or T): elevation associated with OR 4.33 for all-cause mortality (meta-analysis, 10,842 patients). (sources/acute-pe-aha-2026, rating: very high)
• BNP/NT-proBNP: elevation associated with OR 6.57 for short-term all-cause mortality. (sources/acute-pe-aha-2026, rating: very high)
• Lactate (venous or arterial): elevation associated with OR 5.13 for all-cause mortality; 4.54 in normotensive PE; OR 9.05 for PE-related mortality (meta-analysis, 1706 patients). Recommended in Cat C–E (COR 1/B-NR). (sources/acute-pe-aha-2026, rating: very high)

Clinical Risk Scores

• PESI: Age + male sex (+10) + cancer (+30) + heart failure (+10) + chronic lung disease (+10) + HR ≥110 (+20) + SBP <100 (+30) + RR ≥30 (+20) + temp <36°C (+20) + altered mental status (+60) + O₂ sat <90% (+20). Class I (≤65 pts) = lowest risk.
• sPESI: 0 = low risk 30-day mortality; ≥1 = high risk. Variables: age >80, cancer, chronic cardiopulmonary disease, SBP <100, HR ≥110, O₂ sat <90%.
• Hestia criteria: 11 clinical/social criteria; all negative = safe for outpatient management.
• Bova score: SBP 90–100 (+2), troponin elevation (+2), RV dysfunction (+2), HR ≥110 (+1). Stage I (0–2) = lowest risk.

Acute Management

Initial Anticoagulation

• LMWH recommended over UFH for parenteral therapy in Cat C1–E1 (COR 1/B-R); predictable pharmacokinetics, lower recurrent VTE, lower HIT risk, no routine monitoring. (sources/acute-pe-aha-2026, rating: very high)
• DOACs recommended over VKAs for oral anticoagulation (COR 1/B-R); lower major bleeding, lower fatal bleeding, lower all-cause mortality. (sources/acute-pe-aha-2026, rating: very high)
• VKA preferred for thrombotic antiphospholipid syndrome (COR 1/A) — DOACs increase arterial thrombosis risk. (sources/acute-pe-aha-2026, rating: very high)
• Pregnancy: LMWH or UFH only (COR 1/C-LD); DOACs and warfarin contraindicated (COR 3:Harm). (sources/acute-pe-aha-2026, rating: very high)
• Breastfeeding: avoid DOACs — uncertain excretion in breastmilk (COR 1/C-LD). (sources/acute-pe-aha-2026, rating: very high)

PERT

• Multidisciplinary PE Response Team recommended for Cat C–E (COR 1/B-NR); reduces time-to-anticoagulation, decreases IVC filter use, reduces length of stay. (sources/acute-pe-aha-2026, rating: very high)

Hemodynamic Management

• Vasopressors (norepinephrine first-line)/inotropes for cardiogenic shock Cat D2–E2 (COR 1/C-LD). (sources/acute-pe-aha-2026, rating: very high)
• Avoid deep sedation and mechanical ventilation in Cat C–E unless required (COR 3:Harm); sedation blunts compensatory sympathetic tone → cardiac arrest risk even in haemodynamically stable patients. (sources/acute-pe-aha-2026, rating: very high)
• VA-ECMO for Cat E2 refractory shock (COR 2a/B-NR). (sources/acute-pe-aha-2026, rating: very high)

Advanced Therapies

• Systemic thrombolysis (rt-PA 100 mg/2 h): COR 2a for Cat E1–2; COR 2b for Cat D; NOT for Cat A1–C2 (COR 3:Harm). Reduces cardiovascular collapse but increases ICH (2.4% in PEITHO). (sources/acute-pe-aha-2026, rating: very high)
• CDL: COR 2a for Cat E1; COR 2b for Cat D; lower bleeding risk than systemic thrombolysis (PEERLESS trial: no difference vs MT in 30-day mortality/bleeding). (sources/acute-pe-aha-2026, rating: very high)
• Mechanical thrombectomy: COR 2a for Cat E1; COR 2b for Cat D; no lytic agent; FLAME study: 1.9% in-hospital mortality. (sources/acute-pe-aha-2026, rating: very high)
• Surgical embolectomy: COR 2a for Cat E1; >97% survival in modern series; NOT for Cat E2 (mostly post-operative deaths from anoxic brain injury); NOT for Cat A–C3. (sources/acute-pe-aha-2026, rating: very high)

IVC Filters

• Retrievable filters only when anticoagulation contraindicated (COR 2a/B-R); permanent filters increase DVT risk without mortality benefit (PREPIC trial). (sources/acute-pe-aha-2026, rating: very high)
• Routine IVC filter in anticoagulated patients: NOT recommended (COR 3:Harm/A). (sources/acute-pe-aha-2026, rating: very high)
• Retrieve as soon as safe — FDA recommends 29–54 days; failed retrievals more frequent after 90 days. (sources/acute-pe-aha-2026, rating: very high)

Post-PE Follow-Up and Long-Term Anticoagulation

Anticoagulation Duration

• No identifiable/major reversible risk factor: extend beyond 3–6 months indefinitely (COR 1/A); 30–40% recurrence risk at 10 years off anticoagulation. (sources/acute-pe-aha-2026, rating: very high)
• Major reversible risk factor (surgery ≥30 min GA, hospitalisation for medical illness ≥72h, Caesarean section, lower-limb fracture): stop at 3–6 months (COR 1/B-NR); <1%/year recurrence post-surgery. (sources/acute-pe-aha-2026, rating: very high)
• Persistent risk factor (active cancer, autoimmune disease, chronic immobility): extend (COR 1/C-LD). (sources/acute-pe-aha-2026, rating: very high)
• Extended-phase DOAC: half-dose apixaban 2.5 mg BID or rivaroxaban 10 mg daily recommended over full dose to reduce bleeding (COR 1/A); RENOVE trial (n=2768): similar VTE recurrence, lower bleeding with half-dose. (sources/acute-pe-aha-2026, rating: very high)

CTEPD Surveillance

• Ask about PE-related symptoms and functional limitations at every visit for at least 1 year (COR 1/C-LD). (sources/acute-pe-aha-2026, rating: very high)
• Persistent dyspnea ≥3 months: evaluate for CTEPD with TTE + V/Q SPECT/CT; CPET useful adjunct. (sources/acute-pe-aha-2026, rating: very high)
• CTEPD with PH (CTEPH): refer to expert centre (COR 1/C-LD). See entities/CTEPH. (sources/acute-pe-aha-2026, rating: very high)
• Prevalence of CTEPD with PH: ~3% of acute PE; CTEPD without PH likely at least as common but prevalence unknown. (sources/acute-pe-aha-2026, rating: very high)

Contradictions / Open Questions

• Systemic thrombolysis for Cat C3 is uncertain: PEITHO trial prevented cardiovascular collapse but excess ICH; NNT=59 vs NNH=78 for ICH. The role of rescue thrombolysis (treat only those who deteriorate) may be equivalent to prophylactic thrombolysis. (sources/acute-pe-aha-2026, rating: very high)
• CDL vs MT equivalence: PEERLESS trial showed no difference in 30-day mortality or major bleeding, but CDL had more bailout events. Neither directly compared to anticoagulation alone in robust RCT. (sources/acute-pe-aha-2026, rating: very high)
• Long-term outcomes of advanced therapies: Evidence limited to 30–90 days; no data on whether CDL or MT reduces CTEPD incidence or improves long-term functional outcomes. (sources/acute-pe-aha-2026, rating: very high)
• Thrombus burden and risk: Counter-intuitively, meta-analysis found higher all-cause mortality with lower obstruction index; thrombus burden not recommended for risk stratification in Cat A–C. (sources/acute-pe-aha-2026, rating: very high)

Connections

• Related to concepts/Acute-PE-Clinical-Categories
• Related to entities/CTEPH
• Related to entities/Pulmonary-Hypertension
• Related to sources/acute-pe-aha-2026

Sources

• sources/acute-pe-aha-2026