OCT in Post-implantation Assessment

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Summary

OCT in Post-implantation Assessment

Post-implantation follow-up of BVS necessitates unique considerations for which OCT may be particularly advantageous.⁵ Because more intensive lesion preparation is usually required when using BVS, special attention is required to avoid inducing vessel complications such as residual edge dissections outside the scaffold (see Figure 3) or intrascaffold dissections with propagating intramural haematoma, which can potentially lead to improper BVS expansion (see Figure 4). In cases where side branch intervention is necessary after BVS implantation, stent apposition should be carefully determined. Guidewire manipulation with many of the currently available workhorse guidewires is more challenging with BVS than with DES. Reentering the side branch between the BVS and the vessel wall instead of through a BVS cell may occur. In addition, special caution should be taken in case of possible strut fractures.

Since the usual metallic strut shadows are not present with BVS, stent apposition can be assessed easily with OCT (see Figure 5). Although the conformability of BVS is usually excellent, the trade-off is that of somewhat reduced radial expansion, especially in areas of focal resistance such as calcium spots. The usual formula used to determine adequate DES gross-expansion (minimal lumen area > 90 % of the reference vessel area) does not work in the case of BVS. Instead, we propose use of the radial diameter ratio at the site of minimal BVS expansion as a potential marker for uniform radial expansion. Due to the tighter ring structure of BVS compared with modern DES, the problem of plaque prolapse should be essentially the same or even less pronounced with BVS. However, if large residual thrombi or plaque tissue is visible with OCT, post-dilatation is advisable to avoid acute or subacute stent thromboses.

OCT in Long-term Follow-up
The optimal duration of dual antiplatelet therapy after BVS implantation has yet to be determined. There are no data demonstrating that dual antiplatelet therapy can be shortened to three months, as is the case with newer generation DES. Thus, in addition to routine assessment, follow-up of BVS should include OCT evaluation of the percentage of covered struts, the extent of neointima formation and examination of potential recoil patterns. These assessments can serve to increase the knowledge of the long-term performance of this new device and to better define its role in modern percutaneous coronary intervention.