Intravascular radiation for the prevention of recurrence of restenosis in coronary arteries

Despite the use of new technology and adjunctive pharmacological therapy, i n-stent restenosis continues to hamper the outcome of approximately 150,000 patients who undergo stented coronary angioplasty; in the US annually Whil e coronary stenting eliminates elastic recoil and vessel contracture by act ing as a mechanical scaffold within the vessel, it is unable to inhibit exc essive neointimal formation and may actually promote it. Fur years, the gro wth-inhibiting properties of ionising radiation have been used successfully to control benign proliferative disorders. Based on this experience, vascu lar brachytherapy. the intravascular delivery: of radiation, was viewed as a viable solution to inhibit neointimal hyperplasia. A series of studies pe rformed in animal models identified the mechanisms by which radiation may r educe restenosis. Data from these studies showed that endovascular radiatio n reduces restenosis by inhibiting cell proliferation and hy inducing favou rable remodelling. The success of these initial studies led to several doub le-blind. multicentre, placebo-controlled, randomised, clinical trials eval uating intravascular radiation, with either gamma- or beta -radiation sourc es, proved to be an effective solution for tile prevention of neointimal pr oliferation and restenosis. However. an increased rate of late thrombosis i n patients who had received intracoronary radiation did evolve from the ini tial use of this therapy. Prolonged antiplatelet therapy and a reduction in the number of new stents placed at the time of radiation has been shown to minimise these complications. Other concerns that still need to be resolve d include edge effect and geographical miss, Intravascular brachytherapy is currently the only approved therapy for this complex disease. It is clear that there are still on-going concerns that will eventually be clarified wh en the long-term results hom ongoing clinical trials around the world becom e available.