Poor Subpleural Perfusion Predicts Failure After Balloon Pulmonary Angioplasty for Nonoperable Chronic Thromboembolic Pulmonary Hypertension

Background: Poor subpleural perfusion (PSP) in the capillary phase of pulmonary angiography predicts worse outcomes following pulmonary endarterectomy in operable chronic thromboembolic pulmonary hypertension (CTEPH). Balloon pulmonary angioplasty (BPA) has emerged as a treatment for nonoperable CTEPH. The goal of the present article was to assess the association between PSP and BPA failure.

Methods: Subpleural perfusion was classified as poor (defined as subpleural spaces either not perfused or minimally perfused in all segments) or normal. We retrospectively reviewed PSP and hemodynamic variables of 101 consecutive patients who underwent BPA from February 2014 to August 2016. The total cross-sectional area of bronchial arteries was also measured by using CT scanning. Patients were categorized according to hemodynamic results after the last BPA: a failure group (defined as mean pulmonary arterial pressure > 30 mm Hg and a decrease in pulmonary vascular resistance < 30% [n = 15]) or a success group (n = 86).

Results: Although baseline hemodynamic variables were similar between the two groups, PSP was observed in 46.7% of patients in the failure group vs 13.9% in the success group (P = .003). Multivariate analysis revealed that PSP was the only predictor of BPA failure (OR, 4.02 [95% CI, 1.17-13.89]; P = .028). Patients with PSP exhibited poorly developed bronchial arteries compared with patients with normal perfusion (7.0 [5.8-9.6] mm² vs 8.7 [6.9-11.3] mm²; P = .032).

Conclusions: PSP in the capillary phase, suggesting the presence of small vessel disease with diffuse distal thrombosis, is a predictor of BPA failure. PSP was also associated with less developed bronchial arteries, which suggests a key role of bronchial-pulmonary anastomoses in maintaining the pulmonary capillary bed open downstream of the pulmonary arterial obstruction. PSP affected approximately 15% of patients with nonoperable CTEPH who underwent BPA.