---

2026 AHA/ACC Pulmonary Embolism Guideline

Exam-Oriented Updates for Emergency Physicians

---

THE BIGGEST CHANGE: NEW 5-CATEGORY CLASSIFICATION SYSTEM

• C1: no biomarker elevation, no RV dysfunction
• C2: elevated biomarker OR RV dysfunction (not both)
• C3: elevated biomarker AND RV dysfunction
• D1: transient hypotension responding to IV fluids, no end-organ signs
• D2: hypotension + end-organ hypoperfusion (lactate >2 mmol/L, AKI, urine output <0.5 mL/kg/h, cardiac index <2.2, MAP <60)
• E1: persistent hypotension = cardiogenic shock (SCAI stage C)
• E2: refractory cardiogenic shock (SCAI D-E) or cardiac arrest with no ROSC at 30 min

---

SECTION 1: DIAGNOSIS & RISK STRATIFICATION

D-Dimer Rules (Class 2a, Level B-R)

• Age-adjusted D-dimer (age × 10 μg/L for FEU assays) is valid for patients >50 years with LOW or INTERMEDIATE pretest probability (<50%)
• YEARS algorithm remains valid (D-dimer threshold 500 μg/L if ≥1 YEARS criterion; 1000 μg/L if 0 criteria)
• Pregnancy-adapted YEARS is reasonable (Class 2b) - avoids up to 65% of CTPAs in first trimester
• Failure rate for both strategies: <2% missed VTE at 3 months

Exam tip: These strategies are only validated in patients NOT on therapeutic anticoagulation.

Imaging (Class 1 Recommendations)

• CTPA is preferred over V/Q for confirming PE (better peripheral PE detection, allows RV assessment)
• V/Q SPECT preferred over planar V/Q (greater specificity, less radiation) - Class 2a
• In pregnancy with normal CXR: low-dose CTPA is reasonable over perfusion scintigraphy (Class 2a)
• Echo is NOT a diagnostic test for PE (Class 3 - no benefit). Low sensitivity; used for risk stratification after diagnosis

CTPA RV Reporting (Class 1 - NEW emphasis)

• Report the numerical RV/LV ratio (internal diameter, axial or 4-chamber view) - NOT subjective assessment
• RV/LV ≥1.0: sensitivity 85%, specificity 72%
• RV/LV ≥0.9: sensitivity 92%, specificity 56%
• Also report on CTPA: chronic PE features (intravascular webs, PA retraction/dilation, bronchial artery dilation, RV hypertrophy, septal flattening) - identifies CTEPD risk

Echo RV Parameters to Report (Class 1)

Biomarkers (Class 1 - NEW for Lactate)

• Troponin + BNP: measure in all Category C patients
• Lactate (venous or arterial): NOW Class 1 recommendation for Categories C-E - elevated lactate has 5.13× odds of all-cause mortality, 4.54× in normotensive patients
• Normotensive shock (Category D2): isolated hypoperfusion without hypotension (lactate >2, urine <720 mL/24h, creatinine rise ≥0.3 mg/dL/24h, or CI ≤2.2)

Thrombus Burden Scoring

• NOT recommended for short-term risk stratification in Categories A-C (Class 3 - no benefit)
• Anatomic characterization is still useful to plan advanced procedures

---

SECTION 2: ED DISPOSITION DECISIONS

Outpatient Discharge (Class 2a)

• Category A (asymptomatic/incidental): discharge from ED, no hospitalization needed
• Category B (symptomatic, low PESI/sPESI/Hestia): early discharge is generally recommended
• Use Hestia, PESI, or sPESI to guide this decision
• Requires: immediate access to anticoagulant + rapid reliable expert follow-up

Interhospital Transfer

• Categories C3-D with high-risk features (RV dysfunction + elevated biomarkers): transfer to advanced center may be considered (Class 2b, C-LD)
• Category E: DO NOT transfer before stabilization (Class 3 - Harm). Give IV thrombolytics before transfer if needed

PERT Activation (Class 1, B-NR)

• Recommended for Categories C-E (may also benefit Category B with comorbidities like ICH)
• Reduces time to anticoagulation, reduces IVC filter use, decreases LOS
• Analogous to code stroke / STEMI teams

---

SECTION 3: ANTICOAGULATION

General Principles (Class 1)

1. Anticoagulate all PE patients without absolute contraindication
2. LMWH over UFH for initial parenteral therapy (Categories C1-E1) - less recurrent VTE, fewer HIT cases
3. DOACs over VKA for oral anticoagulation (unless contraindicated) - lower major bleeding, less ICH, lower all-cause mortality
4. If imaging delayed in suspected Category C2 or higher + low bleeding risk: consider empiric anticoagulation while awaiting imaging (Class 2a)

Special Populations (High-Yield for Exam)

LMWH Monitoring (Anti-Xa)

• Monitor: peak level 3-5 hours after dose, after ≥3 doses (steady state)
• NOT needed in most patients with weight-based dosing (Class 3 - no benefit, Level A)
• DO monitor in: severe CKD (CrCl <30), ICU patients (Class 2b), extreme obesity (Class 2b)

Post-Procedure Anticoagulation

• After CDL: LMWH preferred over UFH (Class 1, B-NR)
• During CDL: therapeutic OR subtherapeutic UFH acceptable (Class 1, C-LD)

---

SECTION 4: HEMODYNAMIC MANAGEMENT

Vasopressors / Inotropes (Class 1, C-LD)

• Use in Categories D2-E2 (cardiogenic shock)
• Norepinephrine = first choice: increases SVR, modest inotropy, little effect on PVR at ≤15 μg/min
• If NE >15 μg/min: add vasopressin or phenylephrine (NOT more NE - will increase PVR)
• Dobutamine (up to 10 μg/kg/min): adjunct to NE in E1-2, or first agent in Category D2 (normotensive shock with low CO)

Fluids

• Use cautiously in Categories D1-2 only: small boluses ≤500 mL (Class 2b)
• Excessive volume → worsens RV overload

Inhaled Pulmonary Vasodilators (Class 2b, B-R)

• Inhaled nitric oxide / prostacyclins: may be considered in Categories C2-E to reduce RV afterload
• Recent RCT: inhaled NO improved RV size and function at 24h despite missing primary endpoint

Sedation and Intubation - CRITICAL EXAM TOPIC (Class 3 - Harm)

• Avoid deep sedation and mechanical ventilation unless absolutely necessary in Categories C-E
• Sedation blunts sympathetic compensation → can precipitate cardiac arrest even in stable patients
• In surgical series: 19-28% needed CPR after anesthesia induction in hemodynamically stable patients
• When sedation required: have vasopressors, inotropes, and VA-ECMO immediately available
• HFNC preferred over standard nasal cannula for moderate-severe hypoxia (Class 2a)

VA-ECMO (Class 2a, B-NR)

• Reasonable in Category E2 (refractory cardiogenic shock) when resources available
• Continue systemic anticoagulation on VA-ECMO unless bleeding (Class 1)
• Role of additional advanced therapies (CDL/MT) on top of VA-ECMO is uncertain (Class 2b)

---

SECTION 5: ADVANCED THERAPIES

Quick Reference Table (Exam-Ready)

Systemic Thrombolysis Key Points

• FDA-approved agents: streptokinase, urokinase, rt-PA (alteplase 100 mg over 2h = standard dose)
• Tenecteplase: used in trials but NOT FDA-approved for PE
• Lower-dose rt-PA (25-50 mg) may be considered to reduce bleeding (Class 2b) - similar efficacy, less bleeding
• PEITHO trial data: ICH risk 2.4% with thrombolytics; major bleeding 6.3% vs 1.2% placebo
• Rescue thrombolysis: valid strategy - PEITHO showed benefit in patients who deteriorated on anticoagulation alone

Catheter-Directed Thrombolysis (CDL)

• Standard dose: 5-10 mg rt-PA per PA (bilateral = 10-20 mg total over 2-24h)
• Reduced dose (<5 mg/PA): NOT recommended over standard dose (Class 3 - no benefit)
• PEERLESS trial: CDL vs MT for intermediate-risk PE showed no difference in 30-day mortality or major bleeding; MT had less clinical deterioration requiring bailout

Mechanical Thrombectomy (MT)

• FLAME trial (high-risk PE, Category E1): MT achieved 17% primary composite endpoint vs 63.9% with other therapies; in-hospital mortality 1.9% vs 29.5%
• FLARE/EXTRACT-PE: significant RV/LV ratio improvement at 48h with large/moderate-bore MT
• Major bleeding in MT trials: 1-1.7% - very low
• Advantage over CDL: no lytic drug, no indwelling catheter, faster thrombus removal, can treat older thrombus

Clot-in-Transit

• Found in 2-4% of PE patients on echo/CT
• Advanced therapy (any modality) is reasonable over anticoagulation alone in Categories C3-E2 (Class 2a)
• Systemic thrombolysis showed improved survival vs anticoagulation alone in pooled analysis

IVC Filters

• Therapeutically anticoagulated patients: routine IVC filter = Class 3 - Harm (Level A)
• Indications: cannot tolerate anticoagulation (Class 2a), or recurrent PE despite optimal anticoagulation (Class 2b)
• Always use retrievable over permanent filters (Class 1) - PREPIC trial showed permanent filters = more DVT, more IVC thrombosis, no survival benefit
• Retrieve as soon as safe: FDA recommends 29-54 day window; retrieval becomes harder after 90 days
• Need structured follow-up program to maximize retrieval rates (Class 2a)
• In Category D-E patients undergoing advanced intervention: filter benefit is uncertain (Class 2b)

---

SECTION 6: EXTENDED ANTICOAGULATION DECISIONS

Duration Framework

Extended Phase Anticoagulation Drug Choice

• DOAC over VKA (Class 1, Level A) for all patients without contraindication
• Half-dose DOAC recommended in extended phase (Class 1, Level A):
  • Apixaban 2.5 mg BID (down from 5 mg BID)
  • Rivaroxaban 10 mg daily (down from 20 mg daily)
  • RENOVE trial confirmed: similar VTE prevention, lower bleeding with reduced dose
• Cancer patients: DOAC or LMWH preferred over VKA (Class 1)
• API-CAT trial: apixaban 2.5 mg BID vs 5 mg BID in cancer-VTE: similar recurrence (2.1% vs 2.8%), less bleeding with lower dose

Recurrent PE on Anticoagulation

• Confirm with CTPA or V/Q (must show new uninvolved vessel/segment)
• Check for nonadherence, drug interactions, subtherapeutic dosing first
• If truly therapeutic: switch drug CLASS (Class 2a)
• If on reduced-dose DOAC: escalate to full dose same class (Class 2a)
• Cancer + recurrent PE on LMWH: escalate LMWH dose by 20-25% (Class 2a)

---

SECTION 7: FOLLOW-UP (Exam Pearls)

• Within 1 week of discharge: follow-up for education, adherence, bleeding check (Class 1)
• At 3 months: discuss anticoagulation duration, further testing, persistent symptoms (Class 1)
• Every visit for ≥1 year: screen for CTEPD symptoms (dyspnea, exercise limitation) (Class 1)
• Screen for anxiety/depression using questionnaires (Class 2a) - affects 30-50% post-PE
• Unprovoked PE: thorough history, exam + age-appropriate cancer screening (Class 1, Level A); CT/PET-CT cancer screening is NOT recommended (Class 3 - no benefit)
• Thrombophilia testing: only in <55 years or family history + no major reversible risk factor, if it will change management (Class 2b)

Post-PE Chronic Sequelae - CTEPD

• CTEPD (chronic thromboembolic pulmonary disease) = umbrella term encompassing CTEPH + symptomatic RPVO without resting PH
• CTEPH complicates 2.3-4% of acute PE; CTEPD without PH is at least as prevalent
• Evaluate with TTE + lung perfusion scan (V/Q or SPECT/CT) - NOT echo alone (Class 2a)
• CPET is reasonable to exclude CTEPD (Class 2a); cardiopulmonary exercise testing finds cases that echo misses
• Normal V/Q (NPV approaches 100%) essentially excludes CTEPD
• For CTEPD with PH: refer to specialty center (Class 1) - PTE surgery and BPA outcomes are volume-dependent
• Continue anticoagulation until CTEPD evaluation complete (Class 1)
• Pulmonary rehabilitation for persistent dyspnea after CTEPD excluded (Class 1, B-R)
• Routine follow-up CTPA in asymptomatic patients: NOT useful (Class 3 - no benefit)

---

QUICK-FIRE EXAM FACTS

---

COMPARISON: 2011 AHA vs 2019 ESC vs 2026 AHA/ACC

---