Aspirated thrombus weight and volume are not associated with improvements in hemodynamics after large-bore mechanical thrombectomy in pulmonary embolism

Abstract Background Large-bore mechanical thrombectomy (LBMT) is a catheter-directed therapy for acute pulmonary embolism (PE). The relationship between aspirated thrombus weight and volume with outcomes remains unclear. Aims The aim was to evaluate the impact of aspirated thrombus weight and volume on outcomes after LBMT. Methods This prospective, open-label, single-arm, single-center registry study included 48 patients undergoing LBMT using the FlowTriever system (Inari Medical/Stryker, Irvine, CA, USA). Thrombus weight and volume were quantified, and clot composition assessed. Associations between thrombus characteristics and clinical, invasive hemodynamics, echocardiographic parameters, and biomarkers were evaluated immediately after the procedure, at hospital discharge, and at 3-month follow-up. Results Thrombus material was available in 48 patients (31% women), of which 41 presented with intermediate-risk and 7 with high-risk PE. LBMT resulted in significant reductions in systolic pulmonary artery pressures (sPAP) intraprocedurally (− 12.8 ± 8.3 mmHg, p < 0.001), with a further invasively measured decrease through 3 months (− 9.6 ± 10.6 mmHg, p < 0.001). From baseline to discharge, right ventricular coupling improved (+ 0.24, p < 0.001) and right ventricle (RV)/left ventricle (LV) ratio decreased (− 0.23, p < 0.001). NT-proBNP and high-sensitivity cardiac troponin T declined significantly. Neither thrombus weight nor volume correlated with acute changes in sPAP ( ρ volume = 0.06; ρ weight = 0.10), RV-uncoupling ( ρ volume = 0.47; ρ weight = 0.46), and RV/LV ratio ( ρ volume = − 0.02; ρ weight = − 0.005) ( p for all > 0.05), nor with outcomes at 3 months. Conclusions Aspirated thrombus weight and volume were not associated with improvements after LBMT, suggesting that, beyond mechanical obstruction, additional mechanisms potentially including paracrine and endocrine effects of thrombus material may contribute to acute and chronic PE-related cardiopulmonary dysfunction. Graphical Abstract Abbreviations: PE – pulmonary embolism, LBMT – large bore mechanical thrombectomy, PVR - pulmonary vascular resistance, RV – right ventricular, TTE – transthoracic echocardiography, sPAP – systolic pulmonary artery pressure, IQR – interquartile range, BH – Benjamin Hochberg. Acknowledgment: Images partly created with AI