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)
• 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)

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)
• 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)
• Pregnancy-adapted YEARS criteria reduce CTPA exposure by 65% in first trimester (COR 2b/B-NR). (sources/acute-pe-aha-2026)

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)
• 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)
• Echocardiography: NOT useful for confirming or excluding PE diagnosis (COR 3:No Benefit) — most patients with acute PE show no RV dysfunction, so it cannot serve as a diagnostic test; used for RV dysfunction risk stratification only. (sources/acute-pe-aha-2026)
• On CTPA: report numerical RV/LV ratio (cut-point ≥1.0: sensitivity 85%, specificity 72%; COR 1/B-R). Note the echo threshold for the same ratio is >0.9, not ≥1.0 — the values are not transferable between modalities. (sources/acute-pe-aha-2026)

Classification and risk stratification

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

AHA/ACC acute PE categories (A–E)

(Table: sources/acute-pe-aha-2026, rating: very high)

• A is written A1 in the reperfusion recommendations, and the guideline defines no A2.
• Respiratory modifier (R) is appended to any category: for B–D when O₂ requirement exceeds 6 L/min by nasal cannula, a nonrebreather is needed or respiratory rate exceeds 25; for E-R when NIV or invasive ventilation is required. (sources/acute-pe-aha-2026)
• The D2 thresholds are stated inconsistently in the source. The body text gives urine output <720 mL/24 h and cardiac index ≤2.2 L/min/m², whereas the Figure 2 footnote gives <0.5 mL/kg/hr and <2.2 L/min/m²; the table above follows the footnote. Any implementation must pick one. (sources/acute-pe-aha-2026)

Clinical risk scores

The guideline tabulates six scores (its Table 6). Full comparison in concepts/Acute-PE-Clinical-Categories.

• The CPES cut-point is all-or-nothing. Because the score is unweighted and capped at 6, higher risk requires all six factors — a patient with five scores 5 and is classed lower risk. This is the detail most often mis-transcribed, and CPES is the score most closely tied to Category D. (sources/acute-pe-aha-2026, rating: very high)
• An increased CPES score is itself a Category D2 criterion — it appears among the markers of reduced perfusion/end-organ dysfunction alongside SCAI stage, lactate >2 mmol/L, AKI, urine output <0.5 mL/kg/hr, mental status change, cardiac index <2.2 L/min/m² and MAP <60 mmHg. So CPES both predicts normotensive shock and, once elevated, counts as an instance of it.
• The guideline quotes no performance data for CPES of its own — no discrimination statistic, cohort size or cut-point performance. The primary evidence is outside the document: Najarro M, Briceno W, Rodriguez C, et al. "Shock score for prediction of clinical outcomes among stable patients with acute symptomatic pulmonary embolism." Thromb Res. 2024;233:18–24.
• Generic scores perform comparably to PE-specific scores in some studies and are recalculable from routine vital signs. (sources/acute-pe-aha-2026)
• Caveat applying to all of them: no PE-specific score is substantially superior to another, so any validated one may be used — but none had consistently strong predictive ability for individual patients, and "many patients with haemodynamically stable PE who are categorised as higher risk do not develop adverse outcomes." Read them as triage aids, not prognoses. (sources/acute-pe-aha-2026)

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)
• BNP/NT-proBNP: elevation associated with OR 6.57 for short-term all-cause mortality. (sources/acute-pe-aha-2026)
• 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)

Patent foramen ovale in acute PE

• Echocardiography in acute PE identifies both right-to-left shunt through a patent foramen ovale and right heart thrombi, both associated with increased mortality. (sources/acute-pe-esc-2019)
• The PFO becomes dangerous precisely when the RV fails. Elevated right atrial pressure reverses the interatrial gradient and opens the tunnel, permitting paradoxical embolism of a venous thrombus into the systemic circulation — which is why PFO carriers with RV dysfunction and PE carry an excess ischaemic stroke risk.
• PFO is present in ~25% of adults, so its presence is not itself an adverse finding; the adverse finding is a shunting PFO in a patient with a clot in transit or a deep vein thrombus.
• Anticoagulation treats both problems. The PFO in this setting is a conduit, not an indication for closure; closure after PE is considered separately and only in the context of documented paradoxical embolism or a stroke workup. See concepts/Patent-Foramen-Ovale and concepts/PFO-Non-Stroke-Indications.
• Deep vein thrombosis is found in 7–27% of patients worked up for PFO-associated stroke, which is the reverse direction of the same association (sources/pfo-jama-2025, rating: high).

RV assessment

RV imaging is recommended for short-term risk stratification in Categories C–D without shock (COR 1/A), with echocardiography preferred over CT (COR 2a/B-NR); point-of-care ultrasound may substitute where TTE is unavailable. On TTE, report all eight parameters of RV dysfunction and strain — RV/LV ratio, RV end-diastolic diameter, TAPSE, estimated RVSP, McConnell's sign, tricuspid systolic velocity, paradoxical septal motion and IVC respirophasic collapse (COR 1/B-NR) — because accuracy improves when more than one is abnormal, which is why all eight are requested rather than a single index. (sources/acute-pe-aha-2026, rating: very high)

These are general echocardiographic norms, not PE-specific validated cut-points: Table 4 specifies an RV/atrial gradient >30 mm Hg rather than an RVSP cut-off, and its TAPSE and RV/LV thresholds differ from those used in general RV assessment (see Contradictions). (sources/acute-pe-aha-2026)

In meta-analysis, RV dysfunction is associated with all-cause mortality OR 2.0 (1.66–2.40) across 17,090 patients in 55 studies and with short-term death OR 4.81 (1.98–11.68) in a 5,010-patient individual-patient-data analysis; 34% of clinically low-risk patients nonetheless show RV dysfunction, which is why imaging is recommended even at low PESI or sPESI. (sources/acute-pe-aha-2026, sources/acute-pe-esc-2019, rating: very high)

ESC 2019 four-tier predecessor (superseded)

The scheme the A–E categories replaced, and still the taxonomy most published PE trials enrol against. Full mapping in concepts/Acute-PE-Clinical-Categories.

• High — haemodynamic instability. Intermediate-high — no instability, PESI III–V or sPESI ≥1, both RV dysfunction and elevated troponin. Intermediate-low — no instability, elevated score, one or none positive. Low — PESI I–II or sPESI 0 with no RV dysfunction and negative troponin if assessed. (sources/acute-pe-esc-2019)
• The caution the score alone cannot carry: RV dysfunction may be present in patients who look low-risk by clinical score, so RV and biomarker assessment should be considered even when PESI is low or sPESI is 0 (Class IIa), because clinically low-risk patients may still have RV dysfunction (see RV assessment above). (sources/acute-pe-esc-2019)
• ESC avoids "unprovoked"/"idiopathic", describing the index event's risk factor instead. (sources/acute-pe-esc-2019)
• No Category D and no Category A exist in this scheme — incipient cardiopulmonary failure had no ESC counterpart, and the scheme begins from symptomatic presentation, so incidental PE has no place in it. (sources/acute-pe-esc-2019)

Acute management

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)
• VKA preferred for thrombotic antiphospholipid syndrome (COR 1/A) — DOACs increase arterial thrombosis risk. (sources/acute-pe-aha-2026)
• Pregnancy: LMWH or UFH only (COR 1/C-LD); DOACs and warfarin contraindicated (COR 3:Harm). (sources/acute-pe-aha-2026)
• Breastfeeding: avoid DOACs — uncertain excretion in breastmilk (COR 1/C-LD). (sources/acute-pe-aha-2026)
• ESC 2019 differs in high-risk PE: i.v. UFH with a weight-adjusted bolus without delay is recommended for suspected high-risk PE (Class I/C); LMWH or fondaparinux is preferred over UFH only in patients without haemodynamic instability (Class I/A). The ESC rationale is UFH's short half-life and reversibility when thrombolysis or surgery may follow. (sources/acute-pe-esc-2019, rating: very high)
• ESC renal/APS limits on NOACs (Class III/C): not recommended in severe renal impairment, pregnancy or lactation, or antiphospholipid antibody syndrome. Dabigatran not recommended at CrCl <30 mL/min; edoxaban 30 mg once daily at CrCl 15–50 and not recommended <15; rivaroxaban and apixaban used with caution at CrCl 15–29 and not recommended <15. (sources/acute-pe-esc-2019)

PE response team

• 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)

Haemodynamic support

• Vasopressors (norepinephrine first-line)/inotropes for cardiogenic shock Cat D2–E2 (COR 1/C-LD). (sources/acute-pe-aha-2026)
• 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)
• VA-ECMO for Cat E2 refractory shock (COR 2a/B-NR). (sources/acute-pe-aha-2026)

Reperfusion therapies

• HI-PEITHO RCT (2026) — CDL vs anticoagulation alone in intermediate-risk PE: 544 patients (intermediate-risk: RV/LV ≥1.0 + elevated troponin + ≥2 cardiorespiratory distress criteria); ultrasound-facilitated CDL with alteplase (EkoSonic, 7-hour bilateral infusion, mean 16.9 mg) + anticoagulation vs anticoagulation alone. Primary composite (PE-related death + cardiorespiratory decompensation/collapse + PE recurrence at 7 days): 4.0% vs 10.3% (RR 0.39; 95% CI 0.20–0.77; P=0.005). Effect driven by reduction in cardiorespiratory decompensation/collapse (3.7% vs 10.3%). No intracranial haemorrhage in either group. Major bleeding at 30 days: 4.1% vs 3.0% (P=0.64). First RCT to directly compare CDL vs anticoagulation alone; guideline COR 2b for Cat C3–D likely to be upgraded. (sources/cdf-pe-hipeitho-nejm-2026, rating: very high)
• PRAGUE-26 (2026) — conventional CDL confirms the HI-PEITHO result in a broader population: 558 patients with ESC-defined intermediate-high–risk PE (haemodynamic stability + simplified PESI ≥1 + RV dysfunction + elevated troponin or natriuretic peptide) at 11 Czech centres; conventional 4-French valved infusion catheter (not ultrasound-facilitated), alteplase 1-mg bolus per catheter then 1 mg/h per catheter to a maximum 20 mg. Primary composite (death from any cause + recurrent PE + cardiorespiratory decompensation/collapse at 7 days): 0.7% vs 6.8% (RR 0.10; 95% CI 0.02–0.44; P<0.001); risk difference −6.1 pp. Effect driven almost entirely by fewer decompensation events (0.7% vs 5.4%; RR 0.13) — deaths 0 vs 4 and PE recurrence 2 vs 1 were individually non-significant. Clinically relevant bleeding 4.6% vs 5.0% (P=0.85) and major bleeding 1.4% vs 2.2% (P=0.54) — no bleeding excess, unlike systemic thrombolysis. 2 haemorrhagic strokes in the thrombolysis arm (one after infusion during a hypertensive episode, one on day 5 with a documented LMWH overdose) vs 1 ischaemic stroke in the control arm. RV/LV ratio at 24 h 0.94 vs 1.07; median ICU stay 2.1 vs 2.8 days. Conducted without industry sponsorship. (sources/CDT-PE-PRAGUE-26-NEJM-2026, rating: very high)
• ESC 2019's position is watch-and-rescue: rescue thrombolysis for haemodynamic deterioration on anticoagulation is Class I (upgraded from IIa in 2014), while routine primary systemic thrombolysis in intermediate- or low-risk PE is Class III. Percutaneous catheter-directed treatment is IIa only where thrombolysis is contraindicated or has failed in high-risk PE, and IIa as an alternative to rescue thrombolysis — with the explicit statement that the risk-to-benefit ratio of catheter-directed procedures had not been established in intermediate- or low-risk PE. That is precisely the gap HI-PEITHO and PRAGUE-26 later filled. (sources/acute-pe-esc-2019)

Thrombolysis — regimens and contraindications

• Regimens (ESC Table 10): rtPA 100 mg over 2 h (standard); accelerated rtPA 0.6 mg/kg over 15 min, max 50 mg (not officially approved for PE); streptokinase 250,000 IU loading then 100,000 IU/h for 12–24 h; urokinase 4,400 IU/kg loading then 4,400 IU/kg/h for 12–24 h. (sources/acute-pe-esc-2019)
• Absolute contraindications: prior haemorrhagic stroke or stroke of unknown origin, ischaemic stroke within 6 months, CNS neoplasm, major trauma/surgery/head injury within 3 weeks, bleeding diathesis, active bleeding. (sources/acute-pe-esc-2019)
• Relative contraindications: TIA within 6 months, oral anticoagulation, pregnancy or first post-partum week, non-compressible puncture sites, traumatic resuscitation, refractory hypertension (systolic BP >180 mmHg), advanced liver disease, infective endocarditis, active peptic ulcer. (sources/acute-pe-esc-2019)

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)
• Routine IVC filter in anticoagulated patients: NOT recommended (COR 3:Harm/A). (sources/acute-pe-aha-2026)
• Retrieve as soon as safe — FDA recommends 29–54 days; failed retrievals more frequent after 90 days. (sources/acute-pe-aha-2026)
• ESC 2019 adds a second indication: filters should be considered not only with absolute contraindications to anticoagulation (Class IIa/C) but also in PE recurrence despite therapeutic anticoagulation (Class IIa/C) — a scenario the 2026 guideline does not single out. Routine use is not recommended (III/A) in both. Reported complications include filter fracture and/or embolisation, DVT extending to the vena cava, and difficult retrieval of permanent filters. (sources/acute-pe-esc-2019)

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)
• Persistent risk factor (active cancer, autoimmune disease, chronic immobility): extend (COR 1/C-LD). (sources/acute-pe-aha-2026)
• 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)

CTEPD and CTEPH 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)
• Persistent dyspnoea ≥3 months: evaluate for CTEPD with TTE + V/Q SPECT/CT; CPET useful adjunct. (sources/acute-pe-aha-2026)
• CTEPD with PH (CTEPH): refer to expert centre (COR 1/C-LD). See entities/CTEPH. (sources/acute-pe-aha-2026)
• 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)
• ESC 2019 is the origin of this pathway and calls the entity CTED, not CTEPD. Routine clinical evaluation 3–6 months after acute PE (Class I/B); an integrated model of post-PE care involving hospital specialists, qualified nurses and primary care physicians (Class I); referral to a PH/CTEPH expert centre for symptomatic patients with mismatched perfusion defects on V/Q persisting beyond 3 months (Class I/C); further evaluation may be considered in asymptomatic patients with CTEPH risk factors (Class IIb — upgraded from III in 2014). ESC states medical therapy is not indicated in CTED (no PH at rest). (sources/acute-pe-esc-2019, rating: very high)
• ESC's CTEPH risk factor list (Table 13) — from the acute event: previous PE/DVT, large pulmonary arterial thrombi on CTPA, echocardiographic signs of PH/RV dysfunction, CTPA findings suggesting pre-existing chronic thromboembolic disease. Concomitant conditions: ventriculo-atrial shunts, infected chronic i.v. lines or pacemakers, splenectomy, thrombophilic disorders (particularly APS and high factor VIII), non-O blood group, hypothyroidism treated with thyroid hormones, history of cancer, myeloproliferative disorders, inflammatory bowel disease, chronic osteomyelitis. A history of acute PE was reported by 75% of patients in an international CTEPH registry. (sources/acute-pe-esc-2019)

Hospital Authority protocol — anticoagulation and reperfusion

• Diagnostic performance as stated locally: CTPA sensitivity 91%, specificity 78%; V/Q scan sensitivity 41%, specificity 97% when high probability. Pretest probability by Wells or revised Geneva.
• Anticoagulation: LMWH preferred — enoxaparin 1 mg/kg q12h if CrCl >30. Unfractionated heparin is reserved for CrCl <30, for patients in whom rapid reversal may be needed (procedure or thrombolysis), or where subcutaneous absorption is unreliable (obesity, oedema); 5,000 units bolus then 500–1,500 units/h to aPTT 1.5–2.5× control. Warfarin is overlapped with LMWH until INR 2–3.
• DOAC regimens with their lead-ins: dabigatran 150 mg BD after ≥5 days of parenteral anticoagulant; rivaroxaban 15 mg BD for 21 days then 20 mg daily; apixaban 10 mg BD for 7 days then 5 mg BD; edoxaban 60 mg daily after ≥5 days parenteral.
• Haemodynamically significant PE: ICU, cautious fluids, vasopressors, ECMO; systemic thrombolysis with rtPA 100 mg over 2 hours followed by heparin to aPTT 1.5–2.5× control. Surgical embolectomy or catheter-directed therapy if deteriorating or thrombolysis is contraindicated.
• IVC filter where PE recurred on adequate anticoagulation, or where anticoagulation is absolutely contraindicated. (sources/Handbook-HA-2024, rating: high)

Contradictions / Open Questions

• A shunting PFO in acute PE is an established marker of worse outcome and an untested therapeutic target. It is associated with increased mortality and with paradoxical stroke, but no trial has examined closure, thrombolysis escalation, or any PFO-directed strategy in this population — the shunt is treated by treating the PE. Whether a PFO should alter the decision to give thrombolysis in intermediate-risk PE is unanswered. (sources/acute-pe-esc-2019)

• The handbook's risk stratification does not map onto either guideline's categories. It stratifies by haemodynamic instability, then RV dysfunction on imaging and troponin, with PESI for comorbidity — but never uses the ESC 2019 or AHA 2026 category names, so a locally stratified patient cannot be placed directly into the recommendation sets on this page. The substance overlaps; the vocabulary does not. (sources/Handbook-HA-2024, rating: high)

• Guideline disagreement — parenteral agent in high-risk PE. ESC 2019 recommends i.v. UFH with a weight-adjusted bolus without delay in suspected high-risk PE (Class I/C), reserving LMWH/fondaparinux-over-UFH for patients without haemodynamic instability (Class I/A). The 2026 guideline recommends LMWH over UFH for Cat C1–E1, which explicitly includes the Cat E shock patients for whom ESC specifies UFH. UFH's short half-life and reversibility if thrombolysis or surgery follows is the ESC rationale; lower recurrent VTE and no routine monitoring is the 2026 rationale. Both cannot be simultaneously optimal for the same patient, and no trial has compared them in shock. (sources/acute-pe-esc-2019, rating: very high; sources/acute-pe-aha-2026, rating: very high)

• Guideline disagreement — routine reperfusion in intermediate-risk PE. ESC 2019 makes primary systemic thrombolysis Class III in intermediate/low-risk while making rescue lysis on deterioration Class I — watch and rescue. The 2026 guideline makes systemic thrombolysis COR 2b for Cat C3–D2 and COR 3:Harm for Cat C2; ESC does not distinguish C from D. The practical question is what to do with a stable intermediate-high patient before deterioration. PEITHO prevented cardiovascular collapse but produced excess ICH (NNT 59 vs NNH 78), and whether rescue lysis is equivalent to prophylactic lysis remains untested. (sources/acute-pe-esc-2019; sources/acute-pe-aha-2026)

• Catheter-directed lysis — two RCTs settled the versus-anticoagulation question, not the rest. HI-PEITHO (n=544; RR 0.39, P=0.005) and PRAGUE-26 (n=558; RR 0.10, P<0.001) agree in direction, in mechanism (fewer decompensation events, not fewer deaths) and in showing no significant bleeding excess — superseding both guidelines' indirect COR 2b. PRAGUE-26 additionally shows that ultrasound facilitation is not the active ingredient, broadens the indication beyond HI-PEITHO's decompensation criteria, and removes the industry-sponsorship asymmetry (HI-PEITHO was sponsored by the catheter manufacturer; PRAGUE-26 was independently funded). What remains open: neither trial was powered for rare harms (PRAGUE-26 had 2 haemorrhagic strokes, one after an LMWH overdose); CDL vs mechanical thrombectomy has never been tested against an anticoagulation-alone arm (PEERLESS had none); and there are no long-term CTEPD or functional data. (sources/CDT-PE-PRAGUE-26-NEJM-2026, rating: very high; sources/cdf-pe-hipeitho-nejm-2026)

• Imaging definitions are internally inconsistent. Echocardiographic RV/LV is abnormal above 0.9 (Table 4) while CTPA RV/LV is reported at ≥1.0; moving the CTPA cut-point from 1.0 to 0.9 raises sensitivity from 85% to 92% and drops specificity from 72% to 56%, so the two modalities disagree about the same ratio in the same patient and the values are not transferable. They also measure different things: against echocardiographic RV dysfunction, septal deviation on CT is specific but insensitive (sensitivity 0.31, specificity 0.98) while the CT RV/LV ratio trades specificity for sensitivity (sensitivity 0.83, specificity 0.75). The threshold is also borrowed — Table 4 is adapted from general American Society of Echocardiography right-heart guidance, with no PE-specific validation or performance data. (sources/acute-pe-aha-2026)

• TAPSE thresholds disagree across pages. Table 4 sets <1.6 cm as abnormal in acute PE, while concepts/Right-Ventricular-Failure gives ≥17 mm as normal for general RV assessment, leaving 16–17 mm in a grey zone neither source resolves. More broadly, the guideline asks for all eight parameters to be reported and states that accuracy improves with more than one abnormal, but never specifies which combination or count should move a patient between Categories C1, C2 and C3. (sources/acute-pe-aha-2026)

• CTEPH's haemodynamic threshold is inconsistent within the ESC's own output. This guideline requires mean PAP ≥25 mmHg; the 2022 ESC/ERS pulmonary hypertension guideline lowered it to >20 mmHg (see concepts/Pulmonary-Hypertension). A patient with mPAP 21–24 mmHg after PE is therefore CTEPH by the 2022 definition and not by the 2019 one. (sources/acute-pe-esc-2019)

• Thrombus burden runs opposite to outcome. Meta-analysis found higher all-cause mortality with a lower obstruction index, so thrombus burden is not recommended for risk stratification in Cat A–C. (sources/acute-pe-aha-2026)

Connections

• Related to concepts/Patent-Foramen-Ovale — paradoxical embolism, and the PFO that opens when the RV fails
• Related to concepts/Acute-PE-Clinical-Categories
• Related to entities/CTEPH
• Related to concepts/Pulmonary-Hypertension
• Related to concepts/Right-Ventricular-Failure — general RV assessment and the TAPSE threshold that differs from Table 4
• Related to concepts/RV-PA-Coupling
• Related to sources/acute-pe-aha-2026

Sources

• sources/acute-pe-aha-2026
• sources/acute-pe-esc-2019
• sources/pfo-jama-2025
• sources/cdf-pe-hipeitho-nejm-2026
• sources/CDT-PE-PRAGUE-26-NEJM-2026
• sources/Handbook-HA-2024