Imaging insights into suboptimal mechanical thrombectomy in patients presenting with acute pulmonary embolism: A case series

Mechanical thrombectomy (MT) is increasingly utilized for intermediate- and high-risk pulmonary embolism (PE), yet procedural failure remains a challenge. We present three cases of extensive PE treated with MT using various evacuation systems. All cases demonstrated mixed acute and chronic thrombus, computed tomography (CT) evidence of right ventricular strain, and incomplete clot clearance with persistent post-procedural pulmonary hypertension. Although different thrombectomy devices were used, all cases demonstrated similar outcomes of incomplete thrombus evacuation, suggesting that thrombus chronicity was the predominant factor limiting procedural success. Chronic thrombus morphology appears to be the primary determinant of thrombectomy failure and should guide treatment strategy, with imaging serving as a supportive tool to evaluate thrombus chronicity. Pre-procedural imaging features such as eccentric or wall-adherent thrombus, heterogeneous clot density, and RV remodeling can assist in evaluating thrombus chronicity and may help identify patients who are less likely to benefit from MT. Advanced imaging approaches, including radiomics-based analysis of clot texture and heterogeneity on CT, may further refine patient selection and improve outcomes. Careful CT and echocardiographic review should guide procedural candidacy to identify patients who are most likely to benefit from MT, which may be augmented with the use of emerging radiomics-based analyses. The objective of this case series is to highlight the role of thrombus chronicity as a predictor of thrombectomy failure in PE. A second aim is to demonstrate how imaging features on CT and echocardiography correlate with incomplete procedural success. Finally, the series underscores the limitations of currently available thrombectomy devices and discusses the potential of radiomics-based methods to improve patient selection.