Coronary brachytherapy in the drug-eluting stent era: don't bury it alive.

Abstract

When vascular radiation was proposed as a therapy for restenosis prevention more than a decade ago,1 it was received with skepticism. After 20 years of failure to reduce the restenosis rate with various systemic pharmacological agents and devices, it seemed unlikely that intracoronary radiation therapy would successfully defeat this seemingly intractable clinical problem. Vascular biologists challenged the a priori effectiveness of the therapy on the basis of previous experiences with (external-beam) radiotherapy involving vascular structures, and pathologists predicted either delayed restenosis or aneurysm formation at the radiated site. Logistic problems were envisioned; would it be feasible to handle radioactive sources in the catheterization laboratory or accept the radiation oncology team as part of routine percutaneous coronary intervention (PCI)? A combination of dedicated radiation biologists, physicists, oncologists, and cardiologists persisted in demonstrating how this therapy could be safely and effectively utilized to reduce rates of restenosis. They proceeded to optimize intracoronary radiation therapy and make it a safe, feasible, effective, and clinically useful tool to reduce restenosis. Today there are 3 radiation delivery systems approved for routine clinical use in the United States for the treatment of in-stent coronary restenosis (ISR), as follows: a γ-emitting system utilizing the radioisotope Ir192 and 2 β-emitting systems utilizing P32 and Sr90/Y90 sources. The data supporting approval of these technologies for clinical use came from randomized clinical trials that demonstrated superiority of adjunctive intracoronary radiation therapy, or vascular brachytherapy (VBT), over conventional treatment for ISR.2–8 Subset analysis confirmed the benefit of VBT in ISR lesions of varying lengths and vessel diameters, native artery and aortocoronary saphenous vein graft targets, and/or the presence of diabetes.9,10 In 2002, nearly 50 000 brachytherapy procedures were performed for patients with ISR in >500 catheterization laboratories worldwide. With experience, the application of …