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This section introduces PE, its clinical presentation, risk assessment scores and diagnostic strategies
PE is a potential cardiovascular emergency caused by part of a thrombus, usually dislodged from a DVT (subsequently called an embolus), passing into the pulmonary circulation and preventing blood flow to the lungs
The pathway of a pulmonary embolus from the lower part of the body: inferior vena cava, to right atrium, to right ventricle, to the pulmonary artery. This might eventually obstruct blood flow to the lung. Patients with DVT are at risk of PE, a life-threatening event
PE is a potentially life-threatening condition, and in severe cases the occurrence of circulatory collapse and cardiac arrest may result in sudden death
Common signs and symptoms of PE:4
Around 80% of patients with PE have signs of DVT, and approximately 50% of patients with proven proximal DVT have an associated PE.7
None of the above symptoms is specifically diagnostic of PE. The European Society of Cardiology (ESC) guidelines recommend the use of a stepwise diagnostic algorithm that:4
Early mortality risk | Risk parameters and scores | |||
---|---|---|---|---|
Cardiogenic shock or hypotension | PESI class III–V or sPESI >1a | Signs of right ventricular dysfunction on an imaging test | Elevated cardiac biomarkers | |
High | + | (+)b | + | (+)b |
Intermediate high | – | + | Both positive | |
Intermediate low | – | + | Either one (or none) positivec | |
Low | – | – | Assessment optional; if assessed, both negativec |
aPESI Class III–V: moderate to very high 30-day mortality risk; sPESI ≥1 point(s): high 30-day mortality risk. bNeither calculation of PESI (or sPESI) nor laboratory testing are considered necessary in patients with hypotension or cardiogenic shock. cPatients with PESI Class I–II/sPESI of 0, and elevated cardiac biomarkers/signs of right ventricular dysfunction, are to be considered as intermediate-low risk
High-risk PE is usually suspected if cardiogenic shock and/or hypotension are present. Once stabilized, suspected ‘high-risk’ PE patients can undergo CT pulmonary angiography to confirm or dismiss the diagnosis of PE. If PE is not found to be the cause of haemodynamic instability, other causes (such as ACS) should be investigated.4
European Society of Cardiology algorithm for patients with suspected high-risk PE
Adapted from Konstantinides et al.4 aIncludes cases in which the patient’s condition is so critical that it only allows bedside diagnostic tests; bapart from the diagnosis of RV dysfunction, a bedside transthoracic echocardiogram may, in some cases, directly confirm PE by visualizing mobile thrombi in the right heart chambers; cthrombolysis; alternatively, surgical embolectomy or catheter-directed treatment RV, right ventricular
Patients categorized as having ‘low-to-intermediate’ risk PE require further risk stratification using clinical judgement or a clinical prediction rule such as the Wells’ score.4
European Society of Cardiology algorithm for patients with suspected non-high-risk PE
Adapted from Konstantinides et al.4 aTwo alternative classification schemes may be used for clinical probability assessment, i.e. a three-level scheme (clinical probability defined as low, intermediate or high) or a two-level scheme (PE unlikely or PE likely);btreatment refers to anticoagulation treatment for PE; cCT pulmonary angiogram is considered to be diagnostic of PE if it shows PE at the segmental or more proximal level; din case of a negative CT pulmonary angiogram in patients with a high clinical probability, further investigation may be considered before withholding PE-specific treatment
Scoring systems used in clinical practice include several key risk factors and markers for PE based on patient history and presentation. The Wells’ score is commonly used to predict clinical probability of PE.4,8
Parameter | Score |
---|---|
Clinically suspected DVT | 3 |
Alternative diagnosis less likely than PE | 3 |
Rapid heart rate | 1.5 |
Immobilization within past 4 weeks | 1.5 |
History of DVT | 1.5 |
Haemoptysis | 1 |
Malignancy | 1 |
Patients with a high likelihood of PE by the Wells’ score should undergo diagnostic imaging. Those with a low/moderate likelihood should have a D-dimer test; if the latter is positive, imaging should be performed.4
CT pulmonary angiography is the preferred method of diagnostic imaging in patients with a clinical risk score indicative of PE because it provides a high resolution image and is as accurate and less invasive compared with pulmonary angiography, the previous ‘gold standard’.4
A V/Q scan is another established diagnostic test.4
In non-high-risk patients, further risk stratification is necessary once a PE diagnosis has been confirmed. The ESC guidelines recommend use of the PESI or sPESI score to further risk-stratify patients.4
The ESC guidelines recommend that low-risk patients should be considered for early discharge and home treatment providing proper outpatient care and anticoagulant treatment can be provided.4
Parameter | PESI | sPESI |
---|---|---|
Age | Points = age in years | If aged >80 years old = 1 point |
Male sex | +10 points | – |
Cancer | +30 points | 1 point |
Chronic heart failure | +10 points | 1 point |
Chronic pulmonary disease | +10 points | 1 point |
Pulse rate ≥110 beats per minute | +20 points | 1 point |
Systolic blood pressure <100 mmHg |
+30 points | 1 point |
Respiratory rate >30 breaths/min |
+20 points | – |
Temperature <36°C | +20 points | – |
Altered mental status | +60 points | – |
Arterial oxyhaemoglobin saturation <90% | +20 points | 1 point |
Class I: ≤65 points Very low 30-day mortality risk (0–1.6%) Class II: 66–85 points Low mortality risk (1.7–3.5%) |
0 points = low risk Low 30-day mortality risk (1.0%) (95% CI 0–2.1%) |
|
Class III: 86–105 points Moderate mortality risk (3.2–7.1%) Class IV: 106–125 points High mortality risk (4.0–11.4%) Class V: >125 points Very high mortality risk (10.0–24.5%) |
≥1 point(s) = not low risk 30-day mortality risk (10.9%) (95% CI 8.5–13.2%) |
CI, confidence interval
The 2018 British Thoracic Society (BTS) guidelines for outpatient management of PE, recommend treatment with either LMWH plus dabigatran or edoxaban, or a single NOAC (rivaroxaban or apixaban); with preference given to a single NOAC (rivaroxaban or apixaban) regimen to minimize potential confusion over dosing and administration. These guidelines also provide guidance on evaluating patients with PE for outpatient management.9
BTS guidelines for the identification of patients with PE suitable for outpatient management9
*Patients with cancer or those who are pregnant or within 6 weeks’ post-partum may be considered for outpatient management