Classification and current treatment options of in-stent restenosis. Present status and future perspectives.

Coronary stent implantation is currently performed in > 80% of percutaneous coronary interventions. Its main late complication is the development of in-stent restenosis (ISR), occurring in 10-80% of lesions treated in daily practice. The classification by Mehran et al. is most commonly used. Current therapeutic options to treat ISR include repeat balloon angioplasty, repeat stenting, cutting balloon angioplasty, directional coronary atherectomy, rotational coronary atherectomy, brachytherapy, and drug-eluting stents (DES). DES have been effective in reducing binary restenosis in de novo lesions in randomized controlled trials. The novel use of DES to treat ISR has been shown to be safe and effective in multiple studies involving sirolimus- and paclitaxel-eluting stents. As DES implantation becomes more widespread, ISR in DES is emerging as a new problem. The use of debulking techniques to treat ISR in DES is to be cautioned against. In this new era, the optimal treatment of this new problem is currently unknown. We await further data to see whether repeat DES implantation may help solve this vexing clinical problem.