Should You Investigate for Pulmonary Embolism in Sepsis with RV Strain on ECG?
Yes, you should actively investigate for pulmonary embolism in a patient with sepsis showing RV strain on ECG, as PE can coexist with sepsis and significantly impacts mortality if missed, but the diagnostic approach must account for the patient's hemodynamic status and the fact that RV strain is non-specific in critically ill patients.
Diagnostic Approach Based on Hemodynamic Status
If Hemodynamically Unstable (Shock or Hypotension)
Perform immediate bedside echocardiography as the first-line test when PE is suspected, since the absence of RV dysfunction virtually excludes massive PE as the cause of hemodynamic instability 1.
If echocardiography shows unequivocal RV pressure overload (RV/LV ratio ≥1.0, McConnell sign, or right heart thrombi), this justifies emergency reperfusion treatment for PE without waiting for CT if the patient cannot be safely transported 1.
Echocardiography also helps differentiate other causes of shock in sepsis, including pericardial tamponade, severe LV dysfunction, acute valvular dysfunction, or hypovolemia 1.
CT pulmonary angiography (CTPA) remains the definitive test if the patient can be stabilized for transport 1.
If Hemodynamically Stable
Do not rely on ECG findings alone to diagnose PE, as RV strain patterns on ECG are non-specific and can occur in sepsis from multiple causes including hypoxemia, ARDS, or pre-existing cardiac/pulmonary disease 1.
Assess clinical probability using validated tools and check D-dimer if clinically appropriate, though D-dimer interpretation is challenging in sepsis due to frequent elevation from inflammation 1.
CTPA is the diagnostic test of choice in stable patients with suspected PE, as it provides both diagnostic confirmation and prognostic information about RV dysfunction (RV/LV ratio ≥1.0 predicts worse outcomes) 1.
Routine echocardiography is not recommended for diagnosis in hemodynamically stable patients, though it may be useful for risk stratification once PE is confirmed 1, 2.
Key Clinical Considerations
Why PE Must Be Considered in Sepsis
Septic patients are at increased risk for venous thromboembolism due to immobilization, inflammation, and endothelial dysfunction 1.
PE can present with sepsis-like features including tachycardia, hypotension, and respiratory distress, making clinical differentiation difficult 3, 4.
Missing PE in a septic patient has catastrophic consequences, as anticoagulation is the cornerstone of treatment and delays increase mortality 1.
Limitations of ECG in This Context
ECG findings of RV strain (S1Q3T3, right bundle branch block, T wave inversions in anterior leads) occur in only a subset of PE patients and lack specificity in critically ill patients 3, 4, 5.
An ECG score ≥3 can predict RV dysfunction with 76% sensitivity and 82% specificity, but has limited ability to predict adverse outcomes independently 5.
ECG cannot distinguish between RV strain from PE versus other causes common in sepsis (ARDS, pneumonia, pre-existing pulmonary hypertension) 1.
Prognostic Implications of RV Dysfunction
RV dysfunction on imaging (echo or CT) is found in ≥25% of PE patients and independently predicts short-term mortality 1, 2.
An RV/LV ratio ≥1.0 on CT is associated with 2.5-fold increased all-cause mortality and 5-fold increased PE-related mortality 1.
Right heart thrombi, detected in up to 18% of ICU patients with PE, are associated with particularly high early mortality and may influence decisions about thrombolytic therapy 1, 2, 6.
Common Pitfalls to Avoid
Do not dismiss PE based on the presence of sepsis alone – these conditions frequently coexist and both require treatment 7.
Do not use echocardiography as a screening test in stable patients – its negative predictive value of 40-50% means a normal echo does not exclude PE 1.
Do not delay CTPA in stable patients waiting for echocardiography, as CTPA provides both diagnosis and prognostic information in a single test 1.
Be aware that D-dimer has limited utility in sepsis due to frequent elevation from systemic inflammation, though a normal D-dimer in low-probability patients may still be useful 1.
Practical Algorithm
- Assess hemodynamic stability immediately 1
- If unstable: Bedside echo → if RV dysfunction present, consider PE and treat emergently; if no RV dysfunction, investigate other causes of shock 1
- If stable: Calculate clinical probability → proceed to CTPA if PE suspected based on clinical assessment 1
- If PE confirmed: Use imaging findings (RV/LV ratio, cardiac biomarkers) for risk stratification to guide intensity of monitoring and treatment 1, 2, 6