Evaluation of microvasculopathy using dual‐energy computed tomography in patients with chronic thromboembolic pulmonary hypertension

The existence of microvasculopathy in patients with chronic thromboembolic pulmonary hypertension has been suggested. Recently, dual‐energy computed tomography has been used to produce a sensitive iodine distribution map in lung fields to indicate microvasculopathy according to poor subpleural perfusion. Our aim was to evaluate the impact of microvasculopathy on pathophysiology in chronic thromboembolic pulmonary hypertension. According to the extent of poor subpleural perfusion, ninety‐three interventional treatment‐naïve patients were divided into poorly perfused ( n = 49) or normally perfused group ( n = 44). We assessed cardiopulmonary exercise test, right heart catheterization, and dual‐energy computed tomography parameters for quantitative evaluation of lung perfusion of blood volume score. Lung perfusion of blood volume score in normally perfused group was significantly inversely correlated with pulmonary vascular resistance (pulmonary vascular resistance = 6816.1 × lung perfusion of blood volume score −0.793 , R 2 = 0.225, p < 0.01), but lung perfusion of blood volume score in poorly perfused group was not. Poorly perfused group had higher pulmonary vascular resistance (879 ± 409 dynes‐s/cm 5 vs. 574 ± 279 dynes‐s/cm 5 , p < 0.01) and lower lung perfusion of blood volume score (22.1 ± 5.4 vs. 26.4 ± 6.6, p < 0.01) and % diffusing capacity for carbon monoxide divided by the alveolar volume (59.9 ± 15.4% vs. 78.8 ± 14.2%, p < 0.01). Perfusion of blood volume score in the normally perfused group showed an inverse correlation with pulmonary vascular resistance; however, that in poorly perfused group did not. Microvasculopathy might contribute to severe hemodynamics, apart from pulmonary vascular obstruction. In our experience, more than half of treatment‐naïve chronic thromboembolic pulmonary hypertension patients have microvasculopathy.