Ugly CTPA, Good PESI Score – Are They Low Risk?

Written by Chris Thom

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In a retrospective study of 331 low risk acute pulmonary embolism patients, concerning CTPA findings were not associated with adverse clinical outcomes.

Look at the patient, not the CT scan
Many acute PE patients who are ‘low risk’ via PESI score can be safely managed as outpatients. However, the PESI score does not take into account imaging findings that are also associated with higher mortality. This trial investigated whether concerning CTPA findings are associated with increased adverse events in a group of low risk PESI score PE patients.

This was a retrospective single center study of 331 low risk acute PE patients. Amongst these 331, 180 had no concerning findings on CTPA, while 151 had one or more concerning findings (defined as bilateral PE that was saddle or main pulmonary artery [PA], RV:LV ratio > 1, RV enlargement, septal abnormality, or pulmonary infarction). Clinical outcomes between the two low risk groups were similar, with no significant difference in 30-day mortality or need for ICU. However, resource utilization was higher in the concerning CTPA group, with a larger percentage hospitalized (7.8% vs 2.0%, p=0.01), more receiving echocardiography (57.6% vs 27.2%, p<0.001), and a greater number of PERT team activations (22.5% vs 6.1%, p<0.001).

How will this change my practice?
The single center and retrospective nature likely preclude this from being practice changing. While thought provoking, prior evidence demonstrates the predictive value of right heart strain on identifying adverse events in PE. Much of this is with echocardiography, but trials that have included CT have shown the association as well.  It is important to note that compared to echocardiography, CT has been shown to be sensitive for RV strain, but less specific and less predictive of adverse events. In summation, it is difficult to depart from the notion that large PEs causing RV strain should indeed carry a higher risk of mortality and adverse events. Perhaps the association will be weaker for CT in the select group of low risk PESI score patients, as in this trial, but this needs further study in a prospective fashion.  

Source
Adverse Clinical Outcomes Among Patients With Acute Low-risk Pulmonary Embolism and Concerning Computed Tomography Imaging Findings. JAMA Netw Open. 2023 May 1;6(5):e2311455. doi: 10.1001/jamanetworkopen.2023.11455.

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