Intracoronary Brachytherapy: a New Technique to Prevent Restenosis After Percutaneous Coronary Interventions

Percutaneous trans luminal coronary angioplasty (PTCA) is an accepted treatment for coronary artery disease. However, angiographical restenosis is reported in 40-60% of patients after a successful PTCA. Mechanisms involved in the restenosis process are elastic recoil of the artery, local thrombus formation, vascular remodeling with shrinkage of the vessel and an overact healing process with neointimal hyperplasia. Neointimal hyperplasia develops by migration and proliferation of smooth muscle cells and myofibroblasts after balloon induced trauma of the arterial wall and by deposition of an extracellular matrix by the smooth muscle cells. The introduction of the stent in the arsenal of the interventional cardiologist has reduced the restenosis rate to 15-20%, by preventing elastic recoil and negative remodeling. However, the occurrence of restenosis after stent implantation remains unresolved, especially in small vessels and long lesions, where it may exceed 30% of the cases. It is primary caused by neointimal hyperplasia, which occurs due to trauma of the arterial wall by the stent-struts. The treatment of in-stent restenosis with conventional techniques (balloon angioplasty or debulking) is rather disappointing with restenosis rates of 27-63%, which increases with the number of reinterventions. Since radiotherapy had proven to be effective in treating the exuberant fibroblastic activity of keloid scar formation and other non-malignant processes such as ocular pterygia it was assumed that this adjunctive therapy would also inhibit coronary restenosis.