AHA/ACC Acute PE Clinical Categories (2026)

Definition

The AHA/ACC Acute PE Clinical Categories is a five-category (A–E) classification system introduced in the 2026 AHA/ACC multi-society PE guideline. It replaces the AHA 2011 three-tier scheme (massive/submassive/low-risk) and the ESC 2019 four-tier scheme (low/intermediate-low/intermediate-high/high risk) by integrating clinical severity scores, haemodynamic parameters, biomarkers, and RV imaging into a unified framework. Each category drives specific management decisions — from home discharge (Cat A–B) to advanced reperfusion therapies (Cat D–E). The respiratory modifier (R) is applied when significant hypoxaemia or ventilatory support is required.

Key Concepts

Historical Context

• AHA 2011 scheme: low risk (normotensive, no RV dysfunction, no troponin elevation), submassive (SBP ≥90 but RV dysfunction or troponin elevation), massive (SBP <90 for >15 min or requiring inotropic support). (sources/acute-pe-aha-2026, rating: very high)
• ESC 2019 scheme: low risk (PESI I–II or sPESI=0, no RV dysfunction), intermediate-low (elevated score, only one of troponin/RV), intermediate-high (elevated score, both troponin and RV dysfunction), high risk (haemodynamic instability). (sources/acute-pe-aha-2026, rating: very high)
• AHA/ACC 2026 innovation: introduces Category D (incipient/normotensive shock) as a pre-failure state; recognises respiratory modifier; separates out Category A (asymptomatic/incidental PE); provides finer subcategory resolution. (sources/acute-pe-aha-2026, rating: very high)

Category Definitions

Category A — Subclinical (Asymptomatic, Incidental PE)

• Detected incidentally on CT performed for another indication (e.g., cancer staging CT)
• Patient is asymptomatic; no clinical suspicion of PE at time of diagnosis
• A1 example: Asymptomatic lung cancer patient found to have subsegmental PE on staging CT
• Management: Safe for ED discharge home; anticoagulation decision based on clot location and DVT status; no hospitalisation required (sources/acute-pe-aha-2026, rating: very high)

Category B — Symptomatic, Low Clinical Severity

• Symptomatic PE with low clinical severity score: PESI ≤85 (Class I–II), sPESI=0, or Hestia=0
• B1: Single or multiple subsegmental PEs (triage and anticoagulation decision may differ given clot location)
• B2: Segmental or more proximal PEs
• B2 example: Pleuritic pain after hip replacement, sPESI=0, segmental right lower lobe PE without RV enlargement
• Management: Early hospital discharge; outpatient treatment reasonable if access to anticoagulation and follow-up available; Hestia/PESI/sPESI used as decision tools (sources/acute-pe-aha-2026, rating: very high)
• HOME-PE trial (n=1970): Hestia vs sPESI equivalence; ~38% treated as outpatients in each arm; composite adverse outcomes <1.5% at 30 days (sources/acute-pe-aha-2026, rating: very high)

Category C — Symptomatic, Elevated Clinical Severity ± RV/Biomarkers

• Elevated clinical severity score: PESI >85 (Class III–V), sPESI ≥1, or Hestia ≥1
• Subcategories differentiate presence of cardiopulmonary dysfunction:
  • C1: Elevated severity score; normal biomarkers; no RV dysfunction
  • C2: Elevated severity score; one of: elevated cardiac troponin OR RV enlargement/dysfunction
  • C3: Elevated severity score; BOTH elevated troponin AND RV dysfunction (correlates with PEITHO trial population)
• Respiratory modifier (R): hypoxaemia, tachypnoea, or supplemental O₂ requirement
• C1R example: Breast cancer patient with sudden dyspnea, tachycardia, hypoxaemia, bilateral lobar PE, no RV enlargement, no troponin elevation
• Management: Hospitalise; anticoagulation; close monitoring first 24–72 hours; MAP >80 mmHg reassuring (NPV 97.7% for 48h deterioration); MAP <80 mmHg in Cat C3 warrants escalation consideration (sources/acute-pe-aha-2026, rating: very high)

Category D — Incipient Cardiopulmonary Failure (Normotensive Shock)

• Pre-failure state: haemodynamic compromise WITHOUT persistent hypotension
• Subcategories:
  • D1: Transient or recurrent hypotension (SBP <90 or decrease >40 mmHg lasting <15 min) responsive to IV fluids; no end-organ hypoperfusion
  • D2: Transient hypotension PLUS at least one marker of reduced perfusion/end-organ dysfunction: lactate >2 mmol/L, AKI (creatinine increase ≥0.3 mg/dL in 24h), urine output <0.5 mL/kg/hr, cardiac index ≤2.2 L/min/m², MAP <60 mmHg, or SCAI SHOCK stage B/C
• D2 example: Recent spine surgery patient with acute bilateral main PA PE, normal SBP, increasing creatinine, low MAP
• Respiratory modifier (R): >6 L/min nasal cannula or nonrebreather mask required
• FLASH registry: 34% of intermediate-risk patients had normotensive shock (isolated hypoperfusion without hypotension) (sources/acute-pe-aha-2026, rating: very high)
• Management: Hospitalise; vasopressors/inotropes for haemodynamic compromise; advanced therapy (CDL or MT) may be considered; systemic thrombolysis may be considered (sources/acute-pe-aha-2026, rating: very high)

Category E — Cardiopulmonary Failure

• Persistent hypotension/cardiogenic shock
• Subcategories:
  • E1: Recurrent or persistent hypotension (SCAI SHOCK stage C cardiogenic shock); responsive to some extent to vasopressors
  • E2: Refractory cardiogenic shock (SCAI SHOCK stage D–E) OR cardiac arrest without restoration of spontaneous circulation after 30 minutes of resuscitation
• Respiratory modifier E-R: NIV or invasive positive-pressure ventilation required
• E2R example: COVID-19 patient on mechanical ventilation with saddle PE, severe RV hypokinesis on echo, hypotension despite 3 vasopressors
• Management: Advanced therapies recommended for E1 (COR 2a); systemic thrombolysis, CDL, or MT for E1; surgical embolectomy for E1 if surgical candidate; NOT surgery for E2; VA-ECMO for E2 (sources/acute-pe-aha-2026, rating: very high)

Respiratory Modifier (R)

• Added to any category (B–E) when:
  • Cat B–D: O₂ requirement >6 L/min nasal cannula OR RR >25 OR nonrebreather mask needed
  • Cat E-R: NIV or invasive mechanical ventilation
• Important caveat: Deep sedation and mechanical ventilation in Cat C–E should be avoided unless clinically mandatory (COR 3:Harm) — blunts compensatory sympathetic tone and risks cardiac arrest even in haemodynamically stable patients (sources/acute-pe-aha-2026, rating: very high)

Management Summary by Category

Clinical Risk Scores Used Within the System

Key RV Assessment Parameters

• CTPA: Numerical RV/LV ratio (≥1.0: sensitivity 85%, specificity 72% for adverse events) — COR 1/B-R
• TTE: RV/LV end-diastolic ratio >0.9; TAPSE <1.6 cm; RV basal EDD >42 mm; tricuspid systolic velocity >2.6 m/s; estimated RVSP (>30 mmHg); McConnell's sign; paradoxical septal motion; IVC respirophasic collapse — COR 1/B-NR
• Point-of-care ultrasound acceptable if formal TTE unavailable (sources/acute-pe-aha-2026, rating: very high)

Contradictions / Open Questions

• ESC 2019 vs AHA/ACC 2026 terminology: The intermediate-high risk group (ESC) roughly corresponds to Cat C3 (AHA/ACC), but the concepts are not identical; intermediate-low (ESC) corresponds to Cat C1–2. Clinicians using ESC scoring tools need to map across systems.
• Normotensive shock definition: The 34% prevalence of isolated hypoperfusion (Cat D criteria) in intermediate-risk PE (FLASH registry) suggests many patients previously classified as intermediate-low are actually Cat D2 — this may upstage a significant proportion of patients toward advanced therapy. (sources/acute-pe-aha-2026, rating: very high)
• Category transitions: The guideline notes patients may transition between categories as clinical status evolves; no formal re-assessment protocol is defined for when and how to re-categorise.
• Subsegmental PE management (Cat B1): Whether to anticoagulate isolated subsegmental PE without DVT remains controversial; the guideline separates B1 from B2 but does not provide definitive anticoagulation recommendations for asymptomatic subsegmental PE.

Connections

• Related to entities/Pulmonary-Embolism
• Related to entities/CTEPH

Sources

• sources/acute-pe-aha-2026