DIFFERENCES IN HISTOPATHOLOGIC FINDINGS IN RESTENOTIC LESIONS AFTER DIRECTIONAL CORONARY ATHERECTOMY OR BALLOON ANGIOPLASTY

Background Directional coronary atherectomy (DCA) and balloon angiopla sty (percutaneous transluminal coronary angioplasty, PTCA) differ in t heir method of dilating stenotic vessels, It is not known whether ther e is any morphologic difference between restenotic lesions that occur after DCA and those occurring after PTCA. Methods To evaluate histopat hologic differences between restenotic lesions after DCA or PTCA, we r eviewed coronary atherectomy specimens excised from 37 patients with s table angina. Patients were classified into three groups: those with r estenotic lesions after DCA (n = 8), those with restenotic lesions aft er PTCA (n = 14), and those with primary lesions (n = 15), Specimens w ere analyzed immunohistochemically using monoclonal antibodies specifi c for smooth muscle cells (HHF35), endothelial cells (CD31), macrophag e-derived foam cells (CD68) and cell replication activity (Ki-67), In seven patients undergoing repeat DCA, de novo plaques and restenotic p laques were compared. Results Stellate smooth muscle cell (S-SMC) cont ent in restenotic lesions after DCA (87%) was significantly greater th an that in primary lesions (40%; P = 0.032) and that in restenotic les ions after PTCA (43%; P = 0.045). Foam cells tended to be more prevale nt n primary lesions (67%) than in restenotic lesions after DCA (25%; P = 0.062) or after PTCA (36%; P = 0.10). Restenotic lesions after DCA had more S-SMC proliferation and fewer foam cells than did primary le sions. There were no differences in the presence of thrombus, calcific ation, cholesterin, hemosiderin, the percentage of HHF35-positive cell s or Ki-67-positive cells, or neovascularization among the three group s. Conclusions Smooth muscle cell proliferation may have an important role in the development of restenosis after DCA, Fewer foam cells are present in restenotic lesions after DCA or PTCA than are present in pr imary lesions. (C) 1998 Lippincott-Raven Publishers.