Intracoronary brachytherapy for in-stent restenosis: will it remain a viable therapy?

Excerpt

Stent placement has replaced balloon angioplasty as the most commonly performed percutaneous coronary intervention procedure because of its acute and long-term advantages over balloon angioplasty. However, widespread use of stents has also led to a new problem, the in-stent restenosis (ISR). ISR remains a major limitation of stent technology and represents a technical challenge since the recurrence rate after percutaneous intervention is still high, particularly for the diffuse type of ISR. Studies using intravascular ultrasound have demonstrated that the main mechanism of ISR is neointimal proliferation. After innumerable therapeutic failures including systemic drugs, new devices and other mechanical approaches, intracoronary brachytherapy was established to be the first effective antiproliferative treatment for ISR. The predominant vascular response to radiation delivered at the therapeutic doses for intracoronary brachytherapy is chromosomal damage in the vascular smooth muscle cells, fibroblasts and, when present, endothelial cells that results in the loss of the cells’ ability to reproduce, with consequent mitotic cell death [1]. However, with the emergence of clinically validated drug-eluting stents (DES) for reduction of ISR, the future role of intracoronary brachytherapy has become uncertain. At the Asan Medical Center in Seoul, we started performing intracoronary brachytherapy using a ¹⁸⁸Re-MAG₃-filled balloon in March 1999, and we had treated more than 250 patients with ISR by March of this year. In this editorial, we briefly summarise the clinical trials in intracoronary brachytherapy using gamma or beta radiation for the treatment of ISR, with emphasis on its role in the DES era, and assess the value of a ¹⁸⁸Re liquid-filled balloon approach. …