Clinical features and outcomes of unsuccessful mechanical aspiration thrombectomy in acute pulmonary embolism

Large-bore mechanical aspiration thrombectomy (MAT) for acute pulmonary embolism (PE) is thought to be less effective in patients with a component of subacute or chronic thrombus, though no studies directly compare successful and unsuccessful MAT patients. We hypothesized that unsuccessful MAT would be associated with a more subacute or chronic clinical presentation due to the presence of chronic thrombus, and that a subset of unsuccessful MAT patients would suffer unfavorable outcomes.

Retrospective case-series analysis of patients treated at a tertiary care center who underwent MAT for presumed acute PE. Clinical features including duration of symptoms, presenting vitals, laboratory results, imaging, and procedural findings were compared between the successful and unsuccessful MAT patients. Adverse outcomes including in-hospital PE-related mortality were also compared.

The majority of unsuccessful MAT cases (79%) were attributed to chronic thrombus. Unsuccessful MAT patients presented with a longer duration of symptoms (Fisher's exact test p = 0.04), less severe vital sign abnormalities (Shock Index 0.78 vs 1.10, p = 0.0005), and higher preprocedure pulmonary artery systolic pressure (57 vs 48 mmHg, p = 0.06). In-hospital PE-related mortality was higher in the unsuccessful MAT group (36% vs 0%, p = 0.01).

Unsuccessful MAT was mostly attributed to chronic thrombus and was associated with a less acute clinical presentation. A subset of patients that undergo unsuccessful MAT may be high risk for in-hospital mortality. A high index of suspicion for chronic thrombus is crucial when considering patients for MAT. Further study is needed to identify the patients most likely to benefit from this procedure, and those with a thrombus not amenable to MAT.