The Pulmonary Embolism Severity Index (PESI) is a validated clinical prediction rule developed by Aujesky et al. (2005) that stratifies patients with acute pulmonary embolism (PE) into five risk classes based on predicted 30-day mortality. It is derived from 10,354 hospitalised PE patients and assigns points for 11 clinical variables. The PESI score determines which PE patients are at low enough risk to be considered for outpatient treatment or early discharge — an approach supported by multiple randomised controlled trials (OUTREACH, Hestia) that have demonstrated the safety of outpatient management for low-risk PE. The 11 variables and their point values are: patient age in years (1 point per year), male sex (+10), cancer (+30), chronic heart failure (+10), chronic lung disease (+10), heart rate ≥110 bpm (+20), systolic blood pressure <100 mmHg (+30), respiratory rate ≥30/min (+20), temperature <36°C (+20), altered mental status (+60), and SpO2 <90% (+20). PESI Class I (≤65 points) has 30-day mortality of 1.6%; Class II (66–85) 3.5%; Class III (86–105) 7.1%; Class IV (106–125) 11.4%; Class V (>125) 24.5%. The simplified PESI (sPESI) uses binary variables (0 or 1 for each of 6 items) and performs similarly to the full PESI for identifying low-risk patients (sPESI = 0: low risk, <1% 30-day mortality). ESC guidelines recommend the PESI or sPESI as the primary tool for PE risk stratification, combined with right ventricular function (echo/CT-RV strain) and biomarkers (troponin, BNP) to determine the final management pathway.
PESI = Age(years) + 10(male) + 30(cancer) + 10(CHF) + 10(chronic lung) + 20(HR≥110) + 30(SBP<100) + 20(RR≥30) + 20(temp<36°C) + 60(altered mental status) + 20(SpO2<90%)
- 1Confirm diagnosis of acute PE by CT pulmonary angiography (CTPA), V/Q scan, or clinical probability with supportive investigation.
- 2Record the patient's age (1 point per year of age).
- 3Add 10 points if male sex.
- 4Add disease points: cancer +30; CHF +10; chronic lung disease (COPD, ILD, etc.) +10.
- 5Assess vital signs and add: HR ≥110 bpm +20; SBP <100 mmHg +30; RR ≥30/min +20; temperature <36°C +20.
- 6Add: altered mental status (disorientation, lethargy, stupor, coma) +60; SpO2 <90% on room air or supplemental oxygen +20.
- 7Classify by total score: ≤65 = Class I (very low); 66–85 = Class II (low); 86–105 = Class III (intermediate); 106–125 = Class IV (high); >125 = Class V (very high).
Apply Hestia checklist to confirm outpatient eligibility: no massive PE, haemodynamically stable, reliable home support
A young female with no comorbidities and normal vital signs scores only on age in PESI, placing her firmly in Class I — the ideal candidate for safe home management.
Class III patients require inpatient monitoring; consider thrombolysis if haemodynamic deterioration
This patient scores 105 — just at the boundary of Class III. A troponin and echocardiogram to assess right ventricular strain will guide whether he needs escalated therapy.
Haemodynamic compromise (SBP <90 mmHg) = massive PE = systemic thrombolysis or surgical embolectomy
Multiple high-risk features produce a very high PESI score. Haemodynamic instability mandates immediate thrombolytic therapy or mechanical reperfusion.
sPESI = 0 is equivalent to PESI Class I–II for outpatient management decisions
The simplified PESI uses binary scoring for 6 items. A score of 0 confirms very low risk, supporting same-day discharge with oral anticoagulation.
Emergency department PE management: stratifying patients into outpatient vs inpatient treatment pathways using PESI/sPESI., representing an important application area for the Pulmonary Embolism Severity in professional and analytical contexts where accurate pulmonary embolism severity calculations directly support informed decision-making, strategic planning, and performance optimization
PERT activation triggers: PESI Class III–V or haemodynamic instability prompts multidisciplinary PERT consultation., representing an important application area for the Pulmonary Embolism Severity in professional and analytical contexts where accurate pulmonary embolism severity calculations directly support informed decision-making, strategic planning, and performance optimization
Thrombolysis decision support: PESI Class V with haemodynamic instability is the threshold for considering systemic thrombolysis., representing an important application area for the Pulmonary Embolism Severity in professional and analytical contexts where accurate pulmonary embolism severity calculations directly support informed decision-making, strategic planning, and performance optimization
Discharge planning: PESI Class I–II + Hestia criteria = same-day or next-day discharge with DOAC prescription., representing an important application area for the Pulmonary Embolism Severity in professional and analytical contexts where accurate pulmonary embolism severity calculations directly support informed decision-making, strategic planning, and performance optimization
Academic researchers and university faculty use the Pulmonary Embolism Severity for empirical studies, thesis research, and peer-reviewed publications requiring rigorous quantitative pulmonary embolism severity analysis across controlled experimental conditions and comparative studies
Incidental PE
{'title': 'Incidental PE', 'body': 'Incidental PE discovered during CT scanning done for other reasons (e.g., cancer staging CT) represents approximately 20–25% of all PE diagnoses. These patients are often asymptomatic and have lower clot burden. Management should be guided by PESI/sPESI — most incidental PEs fall into low-risk categories and can be managed as outpatients with DOACs for 3 months, although this area lacks large RCT evidence and practice varies.'}
PE in Pregnancy
PE in pregnancy is managed with LMWH (adjusted body weight-dosed), which is safe in pregnancy (unlike DOACs and warfarin). The clinical challenge is diagnostic: D-dimer is elevated in normal pregnancy, and radiation from CTPA is a concern. Compression ultrasound of legs, V/Q scan, and CXR are used to reduce radiation. LMWH is continued throughout pregnancy and for ≥6 weeks postpartum.'}
Cancer-Associated PE
{'title': 'Cancer-Associated PE', 'body': 'Cancer confers a 4–7 fold increased risk of VTE and adds 30 points to the PESI score. Cancer-associated PE has higher recurrence rates, higher bleeding risk, and different anticoagulant considerations. DOACs (apixaban, rivaroxaban, edoxaban) are now preferred over LMWH for cancer-associated VTE (SELECT-D, ADAM VTE, Caravaggio trials), except in patients with gastrointestinal or genitourinary cancers where bleeding risk is higher.'}
PE and Right Heart Thrombus
{'title': 'PE and Right Heart Thrombus', 'body': "Free-floating right heart thrombus ('clot in transit') on echocardiography in a patient with PE is associated with very high mortality (>25%) and warrants emergency treatment — systemic thrombolysis is preferred over anticoagulation alone. Surgical embolectomy or catheter-directed therapy are alternatives. This finding represents an extreme-urgency subgroup within massive/high-risk PE."}
| Class | Score | 30-Day Mortality | Management |
|---|---|---|---|
| I | ≤65 | ~1.6% | Outpatient anticoagulation (if Hestia criteria met) |
| II | 66–85 | ~3.5% | Outpatient or short observation; DOAC |
| III | 86–105 | ~7.1% | Inpatient; assess RV function; anticoagulate |
| IV | 106–125 | ~11.4% | Inpatient; consider PERT; thrombolysis if deteriorates |
| V | >125 | ~24.5% | ICU; systemic thrombolysis or surgical embolectomy |
What is the difference between PESI and sPESI?
The full PESI uses 11 variables with weighted point values (age = 1 per year, cancer = 30 points, etc.), producing scores from <65 to >200+. The simplified PESI (sPESI) uses 6 binary variables (each score 0 or 1): age >80, cancer, chronic cardiopulmonary disease, heart rate ≥110, systolic BP <100, and SpO2 <90%. sPESI = 0 identifies very low-risk patients with <1% 30-day mortality. Both perform similarly for identifying low-risk patients, but the full PESI gives more granular risk stratification across all five classes.
When is outpatient PE treatment safe?
Outpatient PE treatment is safe for PESI Class I–II or sPESI = 0 patients who also meet the Hestia criteria (no haemodynamic instability, no need for thrombolysis, no high bleeding risk, adequate social circumstances, no severe pain requiring IV opioids, no other medical reason for hospitalisation). Multiple RCTs (HOME-PE, OUTREACH) have confirmed non-inferiority of outpatient management with DOACs in appropriately selected low-risk PE.
What anticoagulant is preferred for PE?
DOACs (apixaban, rivaroxaban) are first-line for most PE patients. They have comparable efficacy and better safety than warfarin + heparin (lower major bleeding). Rivaroxaban and apixaban have PE-specific dosing regimens (rivaroxaban 15 mg twice daily for 21 days then 20 mg daily; apixaban 10 mg twice daily for 7 days then 5 mg twice daily). Warfarin + LMWH bridging is used for patients with antiphospholipid syndrome (triple positive) or severe renal failure (eGFR <15–25 mL/min/1.73m2).
When should systemic thrombolysis be given for PE?
Systemic thrombolysis (alteplase 100 mg IV over 2 hours) is indicated for massive PE — defined by haemodynamic compromise (systolic BP <90 mmHg for ≥15 minutes, cardiogenic shock, or cardiac arrest). For submassive PE (haemodynamically stable but RV dysfunction + troponin rise), thrombolysis should be considered only if haemodynamic deterioration occurs despite anticoagulation — the risk of major bleeding (including intracranial haemorrhage ~2%) generally outweighs benefit in haemodynamically stable patients.
What are the ESC PE risk categories?
The ESC 2019 PE guidelines stratify risk into: High Risk (haemodynamic instability — PE-related shock/arrest; immediate thrombolysis or embolectomy), Intermediate-High Risk (PESI III–IV or sPESI ≥1 + both RV dysfunction and elevated troponin — anticoagulate; monitor for deterioration), Intermediate-Low Risk (PESI III–IV or sPESI ≥1 + only one of RV dysfunction or troponin elevation — hospitalise and anticoagulate), and Low Risk (PESI I–II or sPESI = 0 — consider outpatient treatment).
How long should anticoagulation continue after PE?
Duration of anticoagulation after PE: 3 months minimum for all provoked PE (post-surgery, post-trauma, post-immobilisation). Unprovoked PE warrants at least 3 months, with risk-benefit reassessment for extended therapy — for most patients with a first unprovoked PE, extended therapy (indefinitely, with annual risk review) is recommended as recurrence risk is 10% in year 1, 30% at 5 years. Cancer-associated PE: LMWH traditionally, but DOACs (rivaroxaban, apixaban, edoxaban) are now preferred per ADAM VTE, SELECT-D trials.
What is a pulmonary embolism response team (PERT)?
A PERT is a multidisciplinary team — typically including pulmonology, haematology, cardiology, vascular surgery, interventional radiology, and intensivist — that provides rapid expert consultation for complex or high-risk PE cases. PERT activation is typically triggered by massive PE (haemodynamic instability), intermediate-high risk PE, contraindications to anticoagulation, or consideration of catheter-directed thrombolysis. Most major centres now have PERTs, which have been associated with reduced in-hospital mortality.
What is chronic thromboembolic pulmonary hypertension (CTEPH)?
CTEPH is a long-term complication of PE occurring in 2–4% of survivors, where clot does not fully resolve and organises into fibrous tissue causing fixed vascular obstruction and progressive pulmonary hypertension. Symptoms include exertional dyspnoea, reduced exercise tolerance, and right heart failure. CTEPH is diagnosed by V/Q scan (characteristic mismatch defects) and confirmed by right heart catheterisation. Treatment is surgical (pulmonary endarterectomy — potentially curative), balloon pulmonary angioplasty, or medical (riociguat).
Pro Tip
The altered mental status domain (+60 points) is the single most powerful point contribution in the PESI. A patient who is confused in the context of PE is automatically Class III or higher — this single variable reflects the severity of haemodynamic compromise to the brain and should always prompt urgent escalation of care.
Did you know?
The PESI was developed using data from the entire state of Pennsylvania (USA) over a multi-year period — more than 10,000 PE patients — making it one of the most geographically comprehensive datasets ever used to build a clinical prediction rule. The Pennsylvania statewide PE cohort that generated the PESI has since been used to generate at least 15 separate published clinical prediction tools across multiple disease areas.