Effects of Clot Burden and Distribution on Pulmonary Embolism Response Team Patients

<h3>Background</h3> The importance of clot burden on CT scan in determining outcomes in patients with pulmonary embolism (PE) is poorly studied. We sought to analyze the association between PE clot burden and outcomes in patients who underwent a PE response team activation. <h3>Research Question</h3> Does clot burden and distribution impact clinical outcomes in patients with PE? <h3>Study Design and Methods</h3> We performed a retrospective review of patients with PE response team activation between January 2021 and May 2022. Clot obstruction was scored according to percentage of obstructed surface of each central and peripheral vessel using the Mastora scoring system. Based on the median percentage of peripheral and central obstruction, we categorized patients into the following 4 groups: high peripheral only, high central only, high peripheral and central, and neither high peripheral nor high central clot obstruction. Outcomes included ICU transfer, need for pressors within 24 hours, cardiac arrest during admission, in-hospital mortality, and 30-day mortality. Significant associations were analyzed in a multivariable logistic regression model while controlling for potential confounders. <h3>Results</h3> A total of 140 patients met inclusion criteria and were analyzed. Most patients (n = 113, 81%) were treated with anticoagulant therapy alone, whereas 27 patients (19%) received mechanical thrombectomy plus anticoagulant therapy. Patients in the high peripheral only group had increased odds of suffering cardiac arrest during admission (OR, 4.17; 95% CI, 1.06-16.35). The association persisted in multivariable logistic regression (OR, 20.85; 95% CI, 2.85-152.55). <h3>Interpretation</h3> Patients with high peripheral only clot burden have an increased risk of cardiac arrest during hospitalization for incident PE. As such, clot burden and location may be indicators to guide selection of PE-directed therapy. Future studies confirming our findings are warranted.