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 four-tier scheme — the scheme the A–E categories replaced. The criteria below now come from the primary source rather than being described second-hand:
  • High — haemodynamic instability
  • Intermediate-high — no instability, PESI III–V or sPESI ≥1, both RV dysfunction and elevated cardiac troponin
  • Intermediate-low — no instability, PESI III–V or sPESI ≥1, one or none of RV dysfunction / elevated troponin positive
  • Low — no instability, PESI I–II or sPESI 0, and no RV dysfunction, with troponin negative if assessed
  • The guideline attaches an explicit caution to the low-risk tier: RV dysfunction may be present in patients who look low-risk by clinical score, so RV and biomarker assessment should be considered even with a low PESI or sPESI of 0 (Class IIa). A meta-analysis of 21 cohorts (3,295 patients "low-risk" by PESI I–II or sPESI 0) found 34% (95% CI 30–39%) had signs of RV dysfunction. This is why the ESC scheme cannot be applied on the clinical score alone. (sources/acute-pe-esc-2019, rating: very high)
  • An important definitional detail: ESC avoids the terms "unprovoked" and "idiopathic", describing the index event's risk factor instead — whereas the 2026 guideline retains "provoked/unprovoked" language in places. (sources/acute-pe-esc-2019, 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

The guideline tabulates six scores (its Table 6). Note the distinction between a score's range and its risk cut-off — CPES is commonly mis-transcribed on exactly this point.

• The severity gate accepts three alternatives: Low clinical severity = PESI ≤85 or sPESI = 0 or Bova ≤4 (elevated = PESI >85 or sPESI ≥1 or Bova >4). The guideline gives no rule for choosing between them and states elsewhere that no PE-specific score is substantially superior — so the same patient can fall in Category B or C depending on which score is applied. (sources/acute-pe-aha-2026, rating: very high)
• CPES is the score tied to Category D. Because it is unweighted and capped at 6, "higher risk" requires all six factors — a patient with five scores 5 and is classed lower risk. An increased CPES score is also itself one of the D2 hypoperfusion markers, alongside SCAI stage. Its primary evidence is Najarro et al., Thromb Res 2024;233:18–24. (sources/acute-pe-aha-2026, rating: very high)
• None of the scores predicts reliably at the individual level. The guideline states that many haemodynamically stable patients stratified as higher risk do not deteriorate; the scores are triage aids, not prognoses. (sources/acute-pe-aha-2026, rating: very high)

Key RV Assessment Parameters

• CTPA: numerical RV/LV ratio — ≥1.0 (sensitivity 85%, specificity 72% for adverse events) — COR 1/B-R. Moving the cut-point to ≥0.9 raises sensitivity to 92% but drops specificity to 56%
• TTE — Table 4 cut-offs: RV/LV end-diastolic ratio >0.9; RV EDD >30 mm and RV basal EDD >42 mm; TAPSE <1.6 cm is abnormal; tricuspid systolic velocity >2.6 m/sec; pulmonary acceleration time <90 ms or RV/atrial gradient >30 mm Hg (tissue Doppler evidence of PH) — COR 1/B-NR
• All eight parameters should be reported, not a single index: RV/LV end-diastolic ratio; RV end-diastolic diameter; TAPSE; estimated RVSP; McConnell's sign; tricuspid systolic velocity; paradoxical septal motion; IVC respirophasic collapse. Accuracy improves when more than one parameter is abnormal, which is why all eight are requested (sources/acute-pe-aha-2026, rating: very high)
• On RVSP specifically: Recommendation 12 asks for estimated RVSP to be reported, but Table 4 defines an RV/atrial gradient >30 mm Hg — not an RVSP cut-off. These are different measurements, and Table 4 does not give a threshold for RVSP itself
• Table 4 is adapted from ASE right-heart guidance (Rudski et al.), so its thresholds are general echocardiographic norms rather than PE-specific validated cut-points; the guideline states no sensitivity or specificity for them in acute PE (sources/acute-pe-aha-2026, rating: very high)
• Point-of-care ultrasound acceptable if formal TTE unavailable (sources/acute-pe-aha-2026, rating: very high)

Contradictions / Open Questions

• ESC 2019 → AHA/ACC 2026 mapping is approximate, and the differences are not merely nomenclature. Intermediate-high maps most closely to Cat C3, intermediate-low to Cat C1–2, ESC "high" to Cat E, ESC "low" to Cat B. But three structural divergences mean the systems do not translate cleanly: (i) Category D has no ESC equivalent — incipient cardiopulmonary failure ("normotensive shock") is a category the 2019 scheme does not recognise, so such patients were simply "intermediate-risk" under ESC; (ii) ESC has no asymptomatic category — Cat A (subclinical/incidental PE) has no place in a scheme that begins from symptomatic presentation, and ESC treats incidental PE only in the cancer section, where it recommends managing it as symptomatic PE; (iii) ESC uses Hestia for triage to home treatment but not as a risk-classification criterion, whereas AHA/ACC writes Hestia=0 into the definition of Category B. Because PE trial enrolment criteria are written in ESC terms — PRAGUE-26 enrolled the "standard ESC intermediate-high-risk definition" — results must be mapped onto A–E before they can be applied to a category. (sources/acute-pe-esc-2019, rating: very high; sources/acute-pe-aha-2026, rating: very high)
• The two guidelines disagree on the reperfusion threshold in intermediate-risk PE, not just on labels. ESC 2019 makes routine primary systemic thrombolysis Class III in intermediate- or low-risk PE while making rescue thrombolysis on haemodynamic deterioration Class I — a watch-and-rescue strategy. The 2026 guideline instead assigns COR 2b ("may consider") to systemic thrombolysis for Cat C3–D2, i.e. permissive where ESC is restrictive, while assigning COR 3:Harm for Cat C2 where ESC's Class III is non-specific across intermediate and low risk. The practical difference is what to do with a stable intermediate-high patient before deterioration — ESC says do not treat, and plan a contingency; AHA/ACC says treatment may be considered. Neither position is resolved by direct randomized evidence, since PEITHO enrolled only intermediate-risk patients and showed collapse prevention offset by excess ICH. (sources/acute-pe-esc-2019, rating: very high; sources/acute-pe-aha-2026, rating: very high)
• The guidelines also disagree on the parenteral agent in high-risk PE. ESC 2019 recommends i.v. UFH with a weight-adjusted bolus without delay for suspected high-risk PE (Class I/C) and recommends LMWH or fondaparinux over UFH only for patients without haemodynamic instability (Class I/A). The 2026 guideline recommends LMWH over UFH for Cat C1–E1 — which includes the Cat E shock patients for whom ESC specifies UFH. The rationale for UFH in shock is its short half-life and reversibility in a patient who may need thrombolysis or surgery; the rationale for LMWH is lower recurrent VTE and no routine monitoring. Both cannot be simultaneously optimal for the same patient. (sources/acute-pe-esc-2019, rating: very high; sources/acute-pe-aha-2026, rating: very high)
• 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.
• CDL evidence gap now closed by TWO RCTs, and the population is broader than first reported: The AHA/ACC guideline assigned COR 2b to CDL for Cat C3–D on indirect evidence, acknowledging that no RCT had compared CDL with anticoagulation alone. HI-PEITHO (NEJM 2026, n=544; RR 0.39, P=0.005) filled that gap in a selected intermediate-risk population requiring additional decompensation features. PRAGUE-26 (NEJM 2026, n=558) has now reproduced the result in the standard ESC intermediate-high–risk definition (Cat C3/D equivalent — haemodynamic stability + simplified PESI ≥1 + RV dysfunction + elevated troponin or natriuretic peptide) using a conventional 4-French infusion catheter rather than an ultrasound-facilitated system: primary composite 0.7% vs 6.8% (RR 0.10; 95% CI 0.02–0.44; P<0.001), again driven by fewer decompensation events (0.7% vs 5.4%), with clinically relevant and major bleeding not significantly different (4.6% vs 5.0% and 1.4% vs 2.2%). Two haemorrhagic strokes occurred in the thrombolysis arm, both with contributory factors. The COR 2b recommendation is likely to be upgraded — and PRAGUE-26 removes two objections that could have limited HI-PEITHO's generalisability: that ultrasound facilitation was necessary, and that the enrolled population was narrower than the guideline category. (sources/cdf-pe-hipeitho-nejm-2026, rating: very high; sources/CDT-PE-PRAGUE-26-NEJM-2026, rating: very high)
• The benefit is in preventing deterioration, not death — in both trials. PRAGUE-26: deaths 0 vs 4 and PE recurrence 2 vs 1, neither individually significant, with the composite carried by 17 decompensation events. HI-PEITHO showed the same pattern (decompensation 3.7% vs 10.3%). Whether preventing decompensation improves survival — particularly outside tertiary centres where decompensation may be more lethal — is untested. PRAGUE-26's authors note mortality in their trial was very low, plausibly because tertiary centres had immediate rescue reperfusion available, and that most PE patients are treated in smaller regional hospitals. (sources/CDT-PE-PRAGUE-26-NEJM-2026, rating: very high)
• The RV/LV ratio has two different cut-points depending on modality, and the guideline does not reconcile them. Echocardiography uses >0.9 (Table 4); CTPA reporting uses ≥1.0 as the headline (Recommendation 11). The same numerical index therefore means different things in the two modalities, and the guideline's own CTPA data show the stakes — 1.0 gives sensitivity 85% / specificity 72%, while 0.9 gives 92% / 56%. A value of 0.95 is abnormal by echo and normal by CTPA as reported. (sources/acute-pe-aha-2026, rating: very high)
• No rule connects the number of abnormal echo parameters to a category change. The guideline asks for all eight parameters to be reported and states that accuracy improves when more than one is abnormal — but never specifies which combination or count should move a patient between C1, C2 and C3. Category assignment in the RV-dependent band therefore rests on clinical judgement rather than a stated decision rule. (sources/acute-pe-aha-2026, rating: very high)
• TAPSE thresholds disagree between the PE and general-RV literatures. Table 4 sets <1.6 cm as abnormal in acute PE; concepts/Right-Ventricular-Failure gives ≥17 mm as normal for general RV assessment. Values of 16–17 mm fall in a gray zone where the two pages read as disagreeing, and neither source addresses the overlap. (sources/acute-pe-aha-2026, rating: very high)
• CPES's "higher risk" arm requires all six factors. Because the score is unweighted and capped at 6, a patient with five of six factors scores 5 and is classed lower risk — the opposite of how a graded score is usually read. The guideline gives no performance data to indicate how often patients reach 6 or what proportion of Category D2 rests on CPES versus the other six D2 markers. (sources/acute-pe-aha-2026, rating: very high)

Connections

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

Sources

• sources/acute-pe-aha-2026
• sources/acute-pe-esc-2019
• sources/cdf-pe-hipeitho-nejm-2026
• sources/CDT-PE-PRAGUE-26-NEJM-2026