Echocardiography and pulmonary embolism

Echocardiography is not recommended routinely as part of the diagnosis of pulmonary embolism (PE). However, given presenting symptoms and clinical instability associated with PE, patients may have this investigation performed during their admission.The availability and accuracy of CT protocols for PE has reduced the need for additional diagnostic testing. As stated, an echo is not the test of choice for PE, considering only up to 40% of patients with PE will have abnormalities. The value of its use may lie within its prognostication.

Signs suggestive of a PE on echo include, RV dilation and hypokinesis, pulmonary hypertension, tricuspid regurgitation and IVC distention. A decrease in LV size can be seen as a results of a dilated RV and bulging of the interventricular septum. Occasionally (~5%), of patients with PE will have an observed thrombus in the RV on echocardiography, confirming the diagnosis. In acute PE, RV dysfunction while sparing the apex (McConnell's sign) may be seen, which has a documented specificity of 94%.

Moderate to severe RV dysfunction on echo has been linked to increased mortality in acute PE. One Swedish study found a 6 fold increase in death compared to patients with normal RV function. The presence of malignancy was also a negative predictive factor in these patients. This finding was identified as one of the most important predictors of increased death at 3 months post presentation. The increase in associated mortality with RV dysfunction suggests this finding may be useful in supporting the decision for thrombolysis in acute PE. The MAPPET registry (see link), found that patients with moderate to severe RV dysfunction have reduced mortality with thrombolysis (with increased risk of severe bleeding), and those with RV dysfunction given anticoagulants alone were at risk for repeat clot. It should be noted, that these patients had normal blood pressures at the time of thrombolysis. RV dysfunction on echo has also been shown to improve post tPA.

The above information makes a case for echocardiography, by a trained specialist, in the patient presenting with symptoms suggestive of PE, adding another diagnostic piece to the initial assessment. It is also valuable in predicting patients with poor outcomes in the months post evaluation.

Acute PE: a multicentre registry