Transthoracic Echocardiogram Indications in Pulmonary Embolism

Role in High-Risk PE (with hemodynamic instability)

The European Society of Cardiology recommends that bedside TTE should be performed immediately in patients with suspected high-risk PE presenting with shock or hypotension, as the absence of echocardiographic signs of right ventricular (RV) overload or dysfunction virtually excludes massive PE as the cause of hemodynamic instability 1, 2
TTE can provide immediate diagnostic information when CT is not immediately available or when the patient is too unstable to be transported for CT imaging, with a strength of evidence supported by the European Heart Journal 3, 4
In a highly unstable patient, unequivocal echocardiographic evidence of RV dysfunction is sufficient to prompt immediate reperfusion treatment for PE without further testing, as recommended by the European Heart Journal 5
TTE can help in the differential diagnosis of shock by detecting other potential causes such as pericardial tamponade, acute valvular dysfunction, severe LV dysfunction, aortic dissection, or hypovolemia, with a high specificity for these conditions 2, 6

The European Society of Cardiology does not recommend TTE as part of the routine diagnostic workup in hemodynamically stable patients with suspected PE, due to its limited sensitivity for detecting PE in this population 2, 5
TTE may be useful in the differential diagnosis of acute dyspnea when clinical and laboratory findings are ambiguous, with a moderate sensitivity and high specificity for detecting cardiac causes of dyspnea 4
TTE is valuable for risk stratification in confirmed non-high-risk PE to identify patients at intermediate risk who might benefit from more intensive monitoring or treatment, with a strength of evidence supported by the European Heart Journal 1, 4

Key echocardiographic signs of RV pressure overload and dysfunction in PE include RV dilatation, RV hypokinesia, abnormal motion of the interventricular septum, tricuspid regurgitation with peak systolic gradient, and decreased tricuspid annular plane systolic excursion, with a high specificity for PE 1, 2, 4, 6

TTE is recommended for guiding therapeutic options in patients with PE at intermediate risk, with a strength of evidence supported by the European Heart Journal 1, 4
Evidence of RV dysfunction on TTE in normotensive patients with PE identifies those at intermediate risk who may benefit from more intensive monitoring, with a moderate sensitivity and high specificity for predicting adverse outcomes 2, 5
The presence of right heart thrombi, detected in up to 4-18% of PE patients, is associated with RV dysfunction and high early mortality, with a high specificity for predicting adverse outcomes 5

The European Society of Cardiology recommends the use of TTE in suspected high-risk PE with shock or hypotension when CT is not immediately available, for distinguishing cardiac vs. non-cardiac etiology of dyspnea, and for guiding therapeutic decisions in patients with PE at intermediate risk 1, 4
TTE is not recommended as part of the elective diagnostic strategy in hemodynamically stable, normotensive patients with suspected PE, due to its limited sensitivity for detecting PE in this population 1, 4

The European Respiratory Society recommends that echocardiography be performed in hemodynamically unstable patients with suspected PE, as unequivocal signs of RV pressure overload on echocardiography are sufficient to justify emergency reperfusion treatment when immediate CT angiography is not feasible 7
Evidence of RV dysfunction on echocardiography is found in ≥25% of unselected patients with acute PE, and is associated with an elevated risk of short-term mortality in hemodynamically stable patients, according to the European Heart Journal 8
Hemodynamically stable patients with acute PE who have RV dysfunction on echocardiography have a higher risk of short-term mortality, with a 2.29-fold increase in mortality compared to those without RV dysfunction, although the exact mortality rate is not specified 8
The European Heart Journal recommends that RV/LV diameter ratio ≥1.0 and tricuspid annular plane systolic excursion (TAPSE) <16 mm be used as key echocardiographic parameters to assess prognosis in patients with acute PE 8
Echocardiography can identify right-to-left shunt through a patent foramen ovale and the presence of right heart thrombi, both of which are associated with increased mortality in patients with acute PE, according to the European Heart Journal 8
Right heart thrombi are detected in up to 4% of unselected PE patients and up to 18% in intensive care settings, and are associated with high early mortality, as reported in the European Respiratory Journal 7

The European Heart Journal notes that echocardiographic parameters have proved difficult to standardize, which may affect their prognostic value, with a positive predictive value for PE-related death of less than 10% in hemodynamically stable patients 8