From the Guidelines
For a suspected pulmonary embolism (PE), immediate evaluation and treatment are crucial. The initial workup should include:
- Clinical assessment: Evaluate for symptoms such as chest pain, shortness of breath, and syncope, as recommended by the 2019 ESC guidelines 1.
- Laboratory tests: Obtain a D-dimer level, complete blood count, basic metabolic panel, and troponin, as suggested by the ACR Appropriateness Criteria 2, 3.
- Imaging: Perform a computed tomography pulmonary angiogram (CTPA) as the preferred initial imaging test for diagnosing PE, as stated in the 2019 ESC guidelines 1 and the ACR Appropriateness Criteria 2, 3.
- Electrocardiogram (ECG): To evaluate for signs of right ventricular strain, as recommended by the American Heart Association 4.
If the CTPA is positive for PE, initiate anticoagulation therapy immediately, as recommended by the 2019 ESC guidelines 1 and the American Heart Association 4. The recommended initial anticoagulant is:
- Enoxaparin: 1 mg/kg subcutaneously every 12 hours or
- Unfractionated heparin: intravenous bolus of 80 units/kg followed by an infusion of 18 units/kg/hour, adjusted to maintain an activated partial thromboplastin time (aPTT) of 60-80 seconds, as suggested by the American Heart Association 4.
For patients with a high risk of bleeding or those who cannot receive anticoagulation, consider:
- Thrombolytic therapy: with tPA (alteplase) 100 mg intravenously over 2 hours, if there are no contraindications, as recommended by the American Heart Association 4.
In patients with massive PE or those who are hemodynamically unstable, consider:
- Thrombectomy: surgical or mechanical removal of the clot, as recommended by the 2019 ESC guidelines 1 and the American Heart Association 4.
All patients with diagnosed PE should be admitted to the hospital for close monitoring and further management, as recommended by the 2019 ESC guidelines 1 and the American Heart Association 4.
From the Research
Diagnostic Approach
The workup for pulmonary embolism (PE) involves a combination of clinical evaluation, laboratory tests, and imaging studies. The diagnostic strategy should be based on the clinical evaluation of the probability of PE 5. The accuracy of diagnostic tests for PE is high when the results are concordant with the clinical assessment.
Clinical Evaluation
Clinical evaluation involves assessing the patient's symptoms, medical history, and physical examination findings. The clinical probability of PE can be calculated using validated scoring systems, such as the Wells score or the Geneva score 6.
Laboratory Tests
Laboratory tests, such as D-dimer, can be used to help diagnose PE. A negative D-dimer result can help rule out PE in patients with a low clinical probability of the disease 7, 8. However, a positive D-dimer result is not specific for PE and can be elevated in other conditions.
Imaging Studies
Imaging studies, such as computed tomography (CT) scans, ventilation-perfusion scans, and magnetic resonance angiography, can be used to confirm the diagnosis of PE. CT scans are the most commonly used imaging modality for diagnosing PE and are considered the gold standard 9, 8, 6.
Diagnostic Algorithm
A diagnostic algorithm can be used to guide the workup for PE. The algorithm typically involves the following steps:
- Clinical evaluation to determine the probability of PE
- Laboratory tests, such as D-dimer, to help rule out PE in patients with a low clinical probability
- Imaging studies, such as CT scans, to confirm the diagnosis of PE in patients with a high clinical probability or inconclusive laboratory results
- Further testing, such as echocardiography or lower-extremity venous ultrasound, to evaluate for right ventricular dysfunction or deep vein thrombosis in patients with confirmed PE 9, 6
Risk Stratification
Patients with suspected PE should be risk-stratified into high-risk, intermediate-risk, or low-risk categories based on their clinical presentation and diagnostic test results. High-risk patients typically have hemodynamic instability, such as cardiogenic shock or persistent arterial hypotension, and require immediate treatment with thrombolysis or anticoagulation 9, 6. Intermediate-risk patients have right ventricular dysfunction or myocardial injury and require close monitoring and anticoagulation. Low-risk patients have a low clinical probability of PE and can be discharged with outpatient follow-up.