When approaching a patient with pulmonary embolism (PE), what is the role of the Pulmonary Embolism Severity Index (PESI) in guiding treatment decisions?

When to Use PERC, Wells, and PESI in Approaching Pulmonary Embolism

Sequential Application of Risk Stratification Tools

Use PERC and Wells scores BEFORE diagnosis to determine who needs imaging, then use PESI/sPESI AFTER diagnosis to guide treatment location and intensity. These tools serve completely different purposes in the PE diagnostic and management pathway. 1

Pre-Diagnosis Phase: PERC and Wells

PERC Rule (Pulmonary Embolism Rule-Out Criteria)

• Apply PERC first in low-probability patients to potentially avoid any testing - if all 8 criteria are negative (age <50, HR <100, O2 sat ≥95%, no hemoptysis, no estrogen use, no prior VTE, no unilateral leg swelling, no surgery/trauma requiring hospitalization within 4 weeks), PE can be ruled out without D-dimer or imaging
• This is your initial screening tool for very low-risk presentations where clinical gestalt suggests PE is unlikely

Wells Score

• Use Wells score next to stratify pre-test probability and determine imaging strategy
• Wells ≤4 (PE unlikely): proceed with D-dimer; if negative, PE excluded; if positive, obtain CTPA
• Wells >4 (PE likely): proceed directly to CTPA without D-dimer
• The Wells score guides your diagnostic workup, not your treatment decisions

Post-Diagnosis Phase: PESI/sPESI

When PE is Confirmed

Immediately calculate PESI or sPESI to determine treatment location (outpatient vs. inpatient) and intensity of monitoring. 1

PESI Score Application

• PESI Classes I-II (≤85 points) identify low-risk patients with 30-day mortality ≤1.6-3.6% who are candidates for outpatient management 1
• PESI includes 11 variables with differential weighting: age (in years), male sex (+10), cancer (+30), heart failure (+10), chronic lung disease (+10), pulse ≥110 (+20), SBP <100 (+30), respiratory rate >30 (+20), temperature <36°C (+20), altered mental status (+60), O2 sat <90% (+20) 1
• PESI Classes III-V indicate intermediate to high risk requiring inpatient management with escalating monitoring intensity 1, 2

Simplified PESI (sPESI) Application

• sPESI = 0 identifies low-risk patients with 30-day mortality of 1.0-1.1% eligible for outpatient treatment 1
• sPESI uses 6 binary variables (1 point each): age >80, cancer, chronic cardiopulmonary disease, pulse ≥110, SBP <100, O2 sat <90% 1
• sPESI ≥1 indicates intermediate-high risk requiring inpatient management 1, 2
• The simplified version is easier to calculate at bedside but classifies fewer patients as low-risk (33-37%) compared to PESI (41-49%) 3, 4

Treatment Algorithm Based on PESI/sPESI

Low-Risk Patients (PESI I-II or sPESI = 0)

Offer outpatient management with direct oral anticoagulants (apixaban or rivaroxaban) if no exclusion criteria present: 2, 5, 6

• Mandatory exclusions: hemodynamic instability (HR >110, SBP <100, O2 sat <90%), active bleeding or high bleeding risk, severe renal/liver impairment, inability to follow-up, lack of social support 2, 6
• Must have same-day anticoagulation initiated before discharge 6
• Requires robust follow-up pathway with access to prompt care if symptoms worsen 5, 6

Intermediate-Risk Patients (PESI III or sPESI ≥1)

Admit for inpatient management with standard anticoagulation and close monitoring: 1, 2

• Further stratify using RV dysfunction on echo/CTPA and cardiac biomarkers (troponin, BNP) 1
• Intermediate-high risk (RV dysfunction + positive biomarkers): intensive monitoring, consider reperfusion therapy if clinical deterioration 1, 2
• Intermediate-low risk (one or neither positive): standard monitoring with anticoagulation 1

High-Risk Patients (Hemodynamically Unstable)

Immediate inpatient management with consideration of thrombolysis regardless of PESI score 1, 2

Critical Nuances and Pitfalls

Don't Over-Rely on Imaging Alone

• Do not exclude patients from outpatient management based solely on RV dilation on CT or echo - instead, measure cardiac biomarkers (BNP/troponin) for additional risk stratification if RV dilation present 2, 6
• Up to 30-47% of patients classified as "high-risk" by PESI were safely managed as outpatients in real-world practice, suggesting clinical judgment remains important 3

Recognize Special Circumstances

• Concomitant DVT is an adverse prognostic factor (OR 1.9 for 30-day mortality) indicating significant comorbidity, which may influence admission decisions 1, 2
• Right heart thrombi represent a critical exception with 21% mortality requiring thrombolytic therapy 2

Validation Strength

• PESI has been extensively validated with AUC 0.76-0.87 for predicting 30-day mortality across multiple international cohorts 1, 7
• The strength of PESI/sPESI lies in reliably identifying low-risk patients (high negative predictive value 97-98%), not in predicting who will deteriorate 1, 4