The histological characteristics and virtual histology findings of the tissues obtained by a distal protection device during endovascular therapy for peripheral artery disease.

BACKGROUND: Distal embolization (DE) is one of the most serious complications of endovascular therapy (EVT). The purpose of the present study was to characterize the lesions that indicate a high risk of DE in patients undergoing EVT, and to investigate the pathological characteristics of the debris. METHODS: Seventy-three consecutive patients with peripheral artery disease (PAD) underwent EVT with a filter device. Image analyses using grayscale intravascular ultrasound (IVUS) and virtual histology (VH) IVUS were performed and the large debris that was trapped was subjected to histological, immunohistochemical, and immunofluorescence analyses. RESULTS: Sixty-nine patients were successfully treated with a filter device (iliac artery, n=46; femoral artery, n=23). Large debris, which was defined as debris of >2mm in maximal diameter, was confirmed in 33 of 69 patients (48%) and was trapped more frequently in the iliac artery than in the femoral artery. Histological analyses were not performed in 36 of 69 patients (52%) because the debris particles were too small to investigate (<2mm in maximal diameter). The proportion of large debris was significantly higher in lesions with ulceration than in lesions without ulceration (p<0.001). The necrotic core (NC) was significantly more developed in the large debris group than in the small debris group (p<0.05). White thrombi were observed in most of the debris particles, and not only the inflammatory component, but also the stable component caused distal embolisms. Inflammatory cells, mainly CD68-positive cells that were also positive for myeloperoxidase, were observed in approximately half of the debris particles. CONCLUSIONS: Distal protection during EVT would be considered when the lesion is located in the iliac artery, is an ulcerative lesion, and when VH-IVUS determines that the lesion contains NC. The plaque in PAD patients mainly corresponds to the stable phenotype; however, it may also exhibit the characteristics of the vulnerable phenotype.