Restenosis Pattern
Focal or Non-focal
The outcome after treatment of BMS-ISR was significantly better in a focal pattern of restenosis. Mehran et al classified the angiographic pattern of BMS-ISR into four groups, and showed the increasing rates of repeat revascularization in more diffuse patterns of restenosis. There are some studies that investigated the influence of restenosis pattern on the outcome of repeat revascularization for DES-ISR. Most of these studies used the simplified classification based on that of Mehran et al, and compared the outcomes of focal ISR (lesions <10 mm) and non-focal ISR (lesions >10 mm, occlusive lesions). In line with the results of BMS-ISR, focal pattern of restenosis seems to have better outcomes compared to the non-focal pattern (Figure 3). PES restenosis has been shown to have a higher rate restenosis pattern, whereas SES restenosis was associated with a more focal pattern. Therefore, SES restenosis may have a favorable outcome after repeat PCI; however, no study has confirmed the different outcomes of repeat PCI between SES and PES-ISR. The higher incidence of non-focal restenosis in the "real-world" compared to the initial stage of DES studies may lead to increased revascularization failure in the clinical setting.
(Enlarge Image)
Figure 3.
Odds ratio for the recurrent restenosis, TLR, and TVR with same and different DES used for the repeat revascularization. The size of the boxes shows the relative number of the study population. * = unadjusted odds ratio; TLR = target lesion revascularization; TVR = target vessel revascularization; DES = drug-eluting stent.
Stent Fracture, Gap
Stent fracture is recognized as one of the contributors to DES-ISR and the rates of DES fracture have been reported to range from 1%-16%. Multiple factors are known to be associated with increased risk of stent fracture, such as right coronary artery lesions, overlapping stents, SES, etc. Stent gap is a similar condition to stent fracture in terms of deficient local drug delivery and scaffolding support. Especially when there is a geographic miss at the initial DES implantation, the chances of developing restenosis at the gap will be higher. Given the potential cause of the restenosis, adding another DES at the restenosis site seems reasonable if only the fracture site or the gap site presented restenosis. In the case of stent fracture, a flexible stent should be chosen to avoid recurrent fracture.