Effect of large bore mechanical thrombectomy on pulmonary vascular resistance in patients with acute pulmonary embolism

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.

This single-centre 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 haemodynamic indices obtained pre- and post-procedure. The primary objective was to evaluate the effect of LBMT on PVR. The 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, haemodynamic instability, and 90-day hospital readmission) and hospital length of stay (LOS). 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 44% 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).

In patients with intermediate-high risk PE, LBMT significantly reduced PVR and may be a valuable haemodynamic marker of disease severity and treatment response. Elevated post-procedural PVR identified patients at increased risk of adverse outcomes.