The radioisotope stent for the prevention of restenosis.

The use of intracoronary stenting has revolutionized catheter-based revascularization of obstructive coronary artery disease. These devices provide excellent scaffolding, predictable immediate success with the creation of a large, dissection-free luminal cross-section and improved long-term outcomes, when compared to "plain old balloon angioplasty". Despite these improvements restenosis still occurs at unacceptable rate, particularly in smaller vessels and in longer lesions. In this article we review the concept of using a stent implanted with low activities of radioisotope as a means to inhibit the proliferative process that is believed to initiate in-stent restenosis. The potential advantages, as well as the limitations of this means of intravascular brachytherapy are reviewed. This approach has been shown to be effective in certain animal models of restenosis. The initial clinical results with the Phase I safety trials will be summarized. Future directions for this technology, including the evaluation of new stent designs and new radioisotopes will be discussed. The early clinical results with more than 170 implants of low activity 32P Palmaz-Schatz and BX radioactive stents have demonstrated excellent procedural and 30-day event-free survival. Further dose finding safety trials are anticipated in 1998. Implementation of a large scale randomized clinical trial will commence if and when early safety and efficacy data suggest a therapeutic effect from this technology. Thus, future studies will focus on optimal stent design and will evaluate alternative isotopes and dosing strategies.