Effect of Large Bore Mechanical Thrombectomy on Pulmonary Vascular Resistance in Patients with Acute Pulmonary Embolism

Abstract Background In patients with intermediate-risk pulmonary embolism (PE), there are limited tools to assess therapeutic response following catheter-based intervention. This study evaluates pulmonary vascular resistance (PVR), an invasive marker of right ventricular (RV) afterload, and its prognostic significance in acute PE. Methods This single-center retrospective study included patients from October 2020-May 2025 with intermediate-high risk PE undergoing large bore mechanical thrombectomy (LBMT) with pulmonary artery catheter-derived hemodynamic indices obtained pre- and post-procedure. The primary objective was to evaluate the effect of LBMT on PVR. Secondary objective was to evaluate the predictors of post procedure elevated PVR (defined as PVR 2 Wood units, WU) and its effect on clinical composite outcome (PE mortality, resuscitated cardiac arrest, hemodynamic instability and 90-day hospital readmission) and hospital length of stay (LOS). Results A total of 131 patients were included. Following LBMT, median PVR decreased significantly from 2.9 to 1.8 WU (p 0.001), with greater reduction in patients with higher baseline PVR (baseline PVR tertile 3 to 1: 50% vs. 40% vs. 20%; p 0.001). Persistently elevated post procedure PVR (2 WU) was seen in 43.6% of patients. However, the incidence of post-procedure severe PVR 5 WU was extremely low (11.5% pre-procedure, 0.8% post-procedure). Multivariable predictors of elevated post-procedural PVR were pre-procedural mean pulmonary artery pressure (OR: 1.07, 95% CI 1.01-1.14, p = 0.026) and pre-procedural PVR (OR 2.20, 95% CI: 1.20-4.04, p = 0.011). In an age and sex adjusted model, elevated post-procedure PVR was associated with a longer in-hospital LOS of 4.2 days (95% CI: 0.60-7.88; p = 0.023) and a 4-fold higher risk of the composite outcome (20.7% vs 5.3%, adjusted hazard ratio: 4.02, 95% CI: 1.28-12.61, p = 0.017). Conclusions In patients with intermediate-high risk PE, LBMT significantly reduced PVR and may be a valuable hemodynamic marker of disease severity and treatment response. Elevated post-procedural PVR identified patients at increased risk of adverse outcomes.