Restenosis

In the past decade, tremendous progress has been made in reducing the incidence of restenosis with the advent of the drug-eluting stent (DES). With “plain old balloon angioplasty,” rates of acute and chronic vessel occlusion were unacceptably high at ≈30% to 60%, secondary to acute and chronic recoil and constrictive remodeling. The advent of bare-metal stents (BMS) appeared to eliminate the issue of acute and chronic recoil but introduced a new entity, neointimal hyperplasia (NIH), with classical papers unequivocally demonstrating a strong and linear relationship between NIH formation and late lumen loss (LLL). The restenosis rates with BMS were reported to be between 16% and 44%, with higher rates of stenosis attributable to several risk factors, in particular, long lesion length and small vessel caliber.1DES were thus conceived as the next step in tackling this iatrogenic entity of NIH, with large-scale reductions in restenosis rates reported at 0% in highly selective lesions and up to 16% in a broader range of patients and lesions with first-generation DES.1 In contrast to plain old balloon angioplasty and BMS, in which an almost classical gaussian distribution of LLL is seen postprocedurally, the LLL after DES implantation appears to follow a bimodal pattern of distribution (Figure 1).2Figure 1. The bimodal distribution of LLL (A, B) and percentage diameter stenosis (C, D) after Cypher (left) and Taxus (right) implantation. LLL indicates late lumen loss. Reproduced with permission from Byrne et al.2Despite the significant advances in the technology to reduce DES restenosis, conservative estimates still suggest that the incidence of in-stent restenosis (ISR) requiring target vessel revascularization (TVR), so-called DES failure, to be ≈5% to 10%, with one estimate suggesting ≈200 000 repeat revascularizations in the United States alone.3Whereas the pattern of restenosis in BMS has been shown …