Microvasculopathy evaluated by Dual-Energy Computed Tomography in Patients with Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Arterial Hypertension

Abstract Background: Poor subpleural perfusion (PSP) on dual-energy computed tomography (DE-CT) suggests microvasculopathy in chronic thromboembolic pulmonary hypertension (CTEPH). However, it remains unclear whether pathological findings of microvasculopathy in CTEPH are equivalent to those in pulmonary arterial hypertension (PAH). This study aims to elucidate the characteristics of microvasculopathy in patients with CTEPH compared to PAH. Methods: Subpleural perfusion on DE-CT was classified as poor (subpleural spaces in all segments with little or no perfusion) or normal. We retrospectively reviewed the subpleural perfusion on DE-CT and hemodynamics of 23 patients with PAH and 113 with inoperable CTEPH, diagnosed between January 2014 and December 2020. Results: PSP was observed in 51% of patients with CTEPH and 4% with PAH (p <0.01); patient characteristics and hemodynamics were similar in both groups. Patients with CTEPH and PSP had poorer baseline hemodynamics and lower diffusing capacity for carbon monoxide divided by the alveolar volume (DLCO/VA) than those with CTEPH with normal perfusion (pulmonary vascular resistance [PVR]: 768 ± 445 dynes-sec/cm5 vs. 463 ± 284 dynes-sec/cm5, p <0.01; DLCO/VA, 60.4 ± 16.8% vs. 75.9 ± 15.7%, p <0.001). Hemodynamics improved to nearly normal in both groups (PVR: 270 ± 118 dynes-sec/cm5 vs. 220 ± 88 dynes-sec/cm5, p=0.13) after adequate balloon pulmonary angioplasty.Conclusions: PSP on DE-CT, which is one of the specific imaging findings of CTEPH, might suggest a different mechanism of microvasculopathy from that in PAH. However, the hemodynamics at rest improved to nearly normal after balloon pulmonary angioplasty (BPA), despite the existence of PSP.