Efficacy of interventional treatment for patients with chronic thromboembolic pulmonary hypertension with microvasculopathy

Abstract

Abstract Background The existence of microvasculopathy in chronic thromboembolic pulmonary hypertension (CTEPH) had been suggested. However, the impact of microvasculopathy for pathophysiology had been unknown. Recently dual-energy computed tomography (DECT) can produce a sensitive iodine distribution map in lung fields to quantify lung perfusion, which may indicate the existence of microvasculopathy according to poor subpleural perfusion. This study aimed to examine the therapeutic efficacy of interventional treatment (pulmonary endarterectomy or/and balloon pulmonary angioplasty) in CTEPH with microvasculopathy. Methods We retrospectively reviewed poor subpleural perfusion (defined as subpleural spaces either not or minimally perfused in all segments) and hemodynamics of 70 consecutive CTEPH patients who underwent DECT before and after interventional therapy from January 2014 to January 2020. Patients were divided according to poor subpleural perfusion in DECT images before treatment: a microvasculopathy group (MV group, n=37) or a non-microvasculopathy group (Non-MV group, n=33). We evaluated clinical parameters as WHO functional class (WHO-Fc), 6-min walk distance, respiratory function test, cardiopulmonary exercise test, hemodynamic parameters, and DECT parameters at baseline and after the treatments. DECT parameters as quantitative evaluation of pulmonary blood volume (PBV) calculated as the average of entire lung iodine density. Results After interventional treatments, WHO-Fc improved in 33 patients in MV group, and 27 patients in Non-MV group (p=0.50). In MV group, baseline mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR) and VE/VCO2 slope were higher (38.3±9.3 vs. 33.2±10.8 mmHg p=0.04, 818±394 vs. 539±289 dyne*sec/cm5 p<0.01 and 43.7±11.3 vs. 35.2±6.9 p<0.01, respectively) and PBV were lower (43.7±11.3 vs. 35.2±6.9 Hounsfield Unit p<0.01) After the treatments, mPAP, PVR, VE/VCO2 slope and PBV showed almost equivalent between the groups (19.5±4.1 vs. 20.6±5.1 mmHg p=0.35, 272±111 vs 251±109 dyne*sec/cm5 p=0.42, 29.2±6.3 vs. 26.0±6.1 p=0.06 and 27.1±6.6 vs. 29.6±6.6 Hounsfield Unit p=0.13). Diffusing capacity for carbon monoxide (%DLCO/VA) did not improve after treatment in both groups (MV group: 59.5±13.1 to 58.8±11.9% p=0.43. Non-MV group: 77.8±13.4% to 70.5±10.8% P<0.01). Conclusion Hemodynamics, pulmonary perfusion, exercise capacities significantly improved after the treatments in spite of the existence or absence of microvasculopathy. However, DLCO which might indicate the existence of microvasculopathy did not improve. Interventional treatments could not improve microvasculopathy because of their limit of accessibilities. Funding Acknowledgement Type of funding source: None