Novel Angiographic Classification of Each Vascular Lesion in Chronic Thromboembolic Pulmonary Hypertension Based on Selective Angiogram and Results of Balloon Pulmonary Angioplasty

Background - Balloon pulmonary angioplasty (BPA) is an alternative therapy for patients with chronic thromboembolic pulmonary hypertension who are ineligible for standard therapy, pulmonary endarterectomy. Although there are several classifications of vascular lesions, these classifications are based on the features of the specimen removed during pulmonary endarterectomy. Because organized thrombi are not removed during balloon pulmonary angioplasty, we attempted to establish a new classification of vascular lesions based on pulmonary angiographic images. We evaluated the success and complication rate of BPA in accordance with the location and morphology of thromboembolic lesions. Methods and Results - We reviewed 500 consecutive procedures (1936 lesions) of BPA in 97 patients with chronic thromboembolic pulmonary hypertension and investigated the outcomes of BPA based on the lesion distribution and the angiographic characteristics of the thromboembolic lesions, as follows: type A, ring-like stenosis lesion; type B, web lesion; type C, subtotal lesion; type D, total occlusion lesion, and type E, tortuous lesion. The success rate was higher, and the complication rate was lower in ring-like stenosis and web lesions. The total occlusion lesions had the lowest success rate. Tortuous lesions were associated with a high complication rate and should be treated only by operators with extensive experience with BPA. Conclusions - We modified the previous angiographic classification and established a new classification for each vascular lesion. We clarified that the outcome and complication rate of the BPA are highly dependent on the lesion characteristics.