Abstract 15570: Pathology of In-stent Neointima in Atherosclerotic Porcine Peripheral Artery Treated by Drug-coated Balloon

Abstract

Introduction: The use of drug-coated balloons (DCB) is a promising technique to treat in-stent restenosis without adding another metal scaffold. Clinical non-inferiority of DCB for treatment of in-stent restenosis (ISR) has been demonstrated compared to drug eluting stents (DES) implantation. However, pathology of neointima treated by DCB remains unclear. Aim: Pathological study of neointima after DCB treatment for ISR has not been reported. This study aimed to examine the tissue response after DCB treatment and plain old balloon angioplasty (POBA) for ISR pathologically, by using atherosclerotic femoral artery of porcine model. Methods: Using micromini pigs fed high-cholesterol, high-fat diet for 3 months, we stented bare metal stents in femoral arteries. After one month of stenting, dilatation of in-stent region by using DCB, and non-compliance balloon (NCB) as POBA were performed. Optimal coherence tomography and angioscopy showed drug adhesion on luminal surface. One month after the balloon expansion, treated arteries were dissected and stent segments were fixed with 10% buffered formalin and embedded in plastic. Stents were segmented at 3mm intervals and histologic sections were prepared. The neointimal area and blood vessel area were morphometrically evaluated, and the ratio of neointimal area per blood vessel area was calculated. Additionally, number of cells per 1mm 2 neointimal area was counted with digital morphometry. Results: We compared the histology between DCB (n=3, 18 histological sections) and POBA (n=3, 18 histological sections) lesions. The ratio of neointimal area per blood vessel area treated by DCB was 0.17 ± 0.01, while that of POBA was 0.21 ± 0.01 (P value = 0.02) respectively. Additionally, the number of cells per 1mm 2 neointimal area was significantly less in the neointima dilated by DCB (1940.9 ± 150.9), compared to that dilated by NCB (2599.8 ± 190.3) (P value = 0.01). These results suggest that DCB treatment after ISR prevents neointimal thickening by inhibiting proliferation of smooth muscle cells. Conclusions: We examined the pathology of in-stent neointima dilated by DCB in peripheral artery of atherosclerotic porcine model. Pathological analysis showed suppressed neointimal proliferation after DCB compared to POBA.