Читать книгу Interventional Cardiology - Группа авторов - Страница 247

Bioresorbable vascular scaffold represented a revolutionary and ground‐breaking concept in interventional cardiology with early registries suggesting superiority of BVS over DES in restoring vasomotion and remodelling. OCT has been used since the first implants of BVS to study the vessel wall response [110,111] and the timing of the resorption process [112]. OCT performed in two groups of patients respectively at 6 and 24 months (B1, n=45) and 12 and 36 months (B2, n=56) in ABSORB cohort B, showed the maintenance of the scaffold area at follow‐up, with a slight decrease in luminal area as a consequence of neointimal proliferation inside the BVS Unlike metallic stents, which are powerful light reflectors and induce posterior shadowing and blooming artifacts on the vessel surface, polymeric struts of BVS are transparent to the light so that scaffold integrity, apposition to the underlying wall, and changes in the strut characteristics over time can be easily studied. OCT also showed a very delayed and incomplete resorption of the PLLA stuts. The ABSORB II trial was also the first to report inferiority of ABSORB BVS: three year follow‐up was associated with a twofold greater risk of TLF in comparison with Xience V (10% vs 5%; p = 0.0425). ABSORB III trial demonstrated ABSORB BVS inferiority in terms of overall ST. Cumulative meta‐analyses embracing ABSORB II, ABSORB III, AIDA, EVERBIO II and TROFI II trials indicated higher target lesion failure and overall ST with BVS, especially in ACS and STEMI patients [113–116]. Several large registries, including two national trials (ABSORB JAPAN and ABSORB CHINA)[117–118] demonstrated better outcomes of ABSORB BVS when optimal lesion preparation was combined with final high pressure expansion guided by imaging, avoiding too small arteries. Still the meta‐analyses and the early results of the ABSORB IV trial determined the decision to interrupt production of ABSORB BVS in late 2017 [119]. OCT was instrumental in revealing rational mechanisms for their higher thrombogenicity, including higher strut profiles leading to turbulent flow and low radial strength leading to a smaller and more irregular final lumen areas. Occasionally, malapposed stuts were found to crush inside the lumen creating rare instances of late (up to 3 years) stent thrombosis (ScT). More recently a series of very late (5–7 years) follow‐up studies showed absence of ST at this time point and more consistent disappearance of the bioabsorbable stuts with OCT. Despite the failure of first generation BVS, newer BRS based on different technologies (magnesium) are under current examination with OCT liberally used to optimize initial results and confirm the absence of untoward late changes [120].