Published online Oct 26, 2018. doi: 10.4330/wjc.v10.i10.165
Peer-review started: March 28, 2018
First decision: May 2, 2018
Revised: May 21, 2018
Accepted: August 26, 2018
Article in press: August 27, 2018
Published online: October 26, 2018
Bioresorbable vascular scaffold (BVS) initially had incredible success in the first ABSORB studies in 2006-2013, but was consequently deemed a failure due to reported relatively higher rates of target lesion failure (TLF) and device thrombosis in randomized controlled trials. However, BVS performs as well as the metallic drug-eluting stent (DES) with a trend toward some benefits for cardiac mortality.
The exploration of the insights in statistics of the relevant studies has a potential to discover the main obstacles of the BVS research and development preventing major cardiovascular events and therefore improving clinical outcomes adapting the technology in routine clinical practice.
The overarching objective was to supplant the perils of the current standard of care with the polymeric bioresorbable scaffolds.
We evaluated the statistical power in clinical trials such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA, and meta-analyses by the post hoc OR-based sample size calculation, and the patterns of artery remodeling published in papers from ABSORB A and B trials.
The underpowered design was confirmed for some studies such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA trials, and meta-analyses of Polimeni, Collet, and Mahmoud with some unintentional bias (judged by the asymmetrical Funnel plot). ST rates with Absorb BRS were comparable with DES performed with a strategy of the BVS implantation with optimized pre-dilation (P), sizing (S), and post-dilation (P) (PSP) implantation achieving 0.35 per 100 patient-years, which is comparable to the RR 0.49 with bare-metal stents and the RR 1.06 with everolimus DES. Both ABSORB II and ABSORB III trials were powered enough for a five-year follow-up, but the results were not entirely conclusive due to the mostly non-significant fashion of data. The powered meta-analyses were built mostly on statistically poor findings.
The misunderstanding of the pathology of transient scaffolding drives the failures of the clinical trials. More bench studies of the vascular response are required. Several next-generation BVS including multifunctional electronic scaffold grant cardiology with a huge promise to make BVS technology great again.
The biology of transient scaffolding remains mostly unknown. The thin-strut scaffolds and stents with advanced mechanical features are able to partly solve the problem of device thrombosis. Nevertheless, the unclear mechanism of related complications challenges the further development of the technology. Future research must be focused on both bench and bedside studies of vascular biology and pathology of the transient scaffolding in order to understand which mechanism is a leading source of the troubles that we face in routine clinical practice with bioresorbable scaffolds.