Intracoronary radiation therapy for restenosis prevention: status of the clinical trials.
BACKGROUND
Vascular brachytherapy is an evolving field for the prevention of restenosis. The rationale for such therapy is that radiation prevents neointimal proliferation and vessel constriction following vascular injury. In recent years, numerous animal experiments have demonstrated that low doses of radiation when applied following intracoronary intervention reduces proliferation and alters the restenosis rate. This novel approach introduced specific vascular radiation biology and radiation physics aspects, new devices, and platforms to deliver the radiation intraluminally.


METHODS
A variety of beta or gamma isotopes for use in vascular brachytherapy has been suggested. These isotopes need to be delivered intracoronarily to provide the therapeutic dose to the target cell via a safe and user-friendly platform. Two platforms of delivery are available and in practice: catheter-based systems and radioactive stenting. However, these novel applications have to be proven in the clinical arena.


RESULTS
We have been conducting clinical trials with intracoronary brachytherapy since 1994 and are gathering information regarding the feasibility, safety, and effectiveness of this technology. Currently we are in the midst of an intensive clinical investigation using various devices, isotopes doses, and techniques. This report summarizes all the clinical work that has been conducted so far and is currently under investigation in this field.


CONCLUSIONS
Without having the results of the majority of the trials described in this paper, it is difficult at this stage to draw firm conclusions regarding the future of this technology. However, the information presented will serve as a tool for the reader to judge the direction of vascular brachytherapy for prevention of restenosis.
Vascular Brachytherapy Institute, Cardiology Research Foundation, Washington Hospital Center, DC 20010, USA. rxw8@mhg.edu
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D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D001610:Beta Particles / Q000627:therapeutic use; D001918:Brachytherapy / Q000379:methods*; D002986:Clinical Trials as Topic; D003327:Coronary Disease / Q000517:prevention & control / Q000532:radiotherapy* / Q000628:therapy; D005720:Gamma Rays / Q000627:therapeutic use; D006801:Humans; D012008:Recurrence; D015607:Stents