Bilateral proximal CTEPH is associated with worse RV function and RV (mal)adaptation

Abstract

Background: Previous research has shown no differences regarding baseline hemodynamics in proximal versus distal chronic thromboembolic pulmonary hypertension (CTEPH). Right ventricular (RV) afterload was compared solely based on pulmonary vascular resistance (PVR), not on the basis of pulsatile components. Aims: Our hypothesis was that proximal CTEPH leads to increased wave reflection, thereby increasing pulmonary arterial stiffness and changing compliance and/or characteristic impedance, leading to increased RV afterload and worse RV function at baseline in bilateral proximal CTEPH compared to bilateral distal CTEPH. Methods: We retrospectively analysed cardiac MRI (RV volumes and ejection fraction (RVEF)) and hemodynamics (mean pulmonary artery pressure (mPAP) and PVR) in 113 CTEPH patients. CTEPH subtype was determined for every lung based on CT-pulmonary angiography; patients with bilateral proximal disease or bilateral distal disease were included in the final analysis. Results: 33 patients with bilateral proximal CTEPH compared to 48 patients with bilateral distal CTEPH showed a significantly lower baseline RVEF (median 28% vs 48%, p 0.01) and more maladaptive RV dilatation (significantly higher RV end-diastolic (median 176 vs 113 mL, p 0.01) and end-systolic volumes (median 71 vs 43 mL, p 0.02)). mPAP and PVR did not differ between groups. Calculated arterial compliance and RC time were not different between groups. Conclusion: RV function was significantly worse in bilateral proximal CTEPH compared to bilateral distal CTEPH, despite similar mPAP and PVR. Compliance and RC time constant were not different between groups. Further analysis of characteristic impedance will be performed.