Mechanical thrombectomy improves left ventricular filling in intermediate-high risk pulmonary embolism: the role of ventricular interdependence

BACKGROUND AND PURPOSE: Acute pulmonary embolism (PE) is the third most common acute cardiovascular condition and remains associated with high mortality. To address the need for risk-adapted therapy, new catheter-directed approaches have emerged for patients with severe PE. While clinical benefits have been shown, underlying mechanisms are poorly understood. This study investigated the impact of mechanical thrombectomy using the FlowTriever device in intermediate-high-risk PE on ventricular filling as a key determinant of systemic hypoperfusion. MATERIAL AND METHODS: We analysed 26 patients with CT-confirmed intermediate-high-risk PE who underwent mechanical thrombectomy using the FlowTriever device. Only patients with post-interventional cross-sectional imaging were included. Main outcome measures comprised changes in invasively assessed haemodynamic parameters, including pulmonary artery and pulmonary capillary wedge pressures (PAP, PCWP), as well as ventricular septal curvature, three-dimensional biventricular volumes, and Doppler-derived indices of diastolic function. RESULTS: Thrombectomy significantly reduced systolic PAP (baseline 64.4 ± 19.9 mmHg, Δ = - 13.6 mmHg, p < 0.0001) and PCWP (baseline 21.7 ± 6.9 mmHg, Δ = - 4.0 mmHg, p < 0.001). Right ventricular (RV) volumes and septal bowing decreased, whereas left ventricular (LV) volumes and transmitral filling parameters improved (E/e', p = 0.0002). Septal curvature strongly correlated with sPAP (r = 0.84) and LV filling pressure (r = - 0.51 with E/e'), indicating its potential as a surrogate marker linking RV pressure overload to impaired LV diastolic filling. CONCLUSIONS: Mechanical thrombectomy in intermediate-high-risk PE not only relieves RV overload but also enhances LV filling by mitigating ventricular interdependence. These findings provide a mechanistic explanation for improved systemic perfusion and warrant confirmation in prospective studies.