The State of the Absorb Bioresorbable Scaffold

Abstract

Significant progress has been made in the percutaneous coronary intervention technique from the days of balloon angioplasty to modern-day metallic drug-eluting stents (DES). Although metallic stents solve a temporary problem of acute recoil following balloon angioplasty, they leave behind a permanent problem implicated in very late events (in addition to neoatherosclerosis). BRS were developed as a potential solution to this permanent problem, but the promise of these devices has been tempered by clinical trials showing increased risk of safety outcomes, both early and late. This is not too dissimilar to the challenges seen with first-generation DES in which refinement of deployment technique, prolongation of dual antiplatelet therapy, and technical iteration mitigated excess risk of very late stent thrombosis, making DES the treatment of choice for coronary artery disease. This white paper discusses the factors potentially implicated in the excess risks, including the scaffold consideration and deployment technique, and outlines patient and lesion selection, implantation technique, and dual antiplatelet therapy considerations to potentially mitigate this excess risk with the first-generation thick strut Absorb scaffold (Abbott Vascular, Abbott Park, Illinois). It remains to be seen whether these considerations together with technical iterations will ultimately close the gap between scaffolds and metal stents for short-term events while at the same time preserving options for future revascularization once the scaffold bioresorbs.

A modified predilation, sizing, and postdilation scoring system for patients undergoing metallic drug‐eluting stent implantations

“…Different materials comprise the stents' platforms, namely, polylactic acid and metal. Compared with metallic DESs, BRSs comprise material with lower ductility and a low modulus of elasticity, which limit the effects of postdilation; therefore, slightly oversized noncompliant balloons should be chosen for aggressive high‐pressure dilation to maximize the inner stent diameter, reduce shear stress, and avoid stent malapposition. However, more aggressive postdilation may not be suitable for metallic DESs.…”

“…The BRS‐derived PSP technique comprised the following criteria: a QCA‐RVD ≥2.25 and ≤4.25 mm; predilation of all lesions with a balloon‐to‐QCA‐RVD ratio ≥1:1, and postdilation with a noncompliant balloon at ≥18 atm with a balloon diameter that was larger, but ≤0.5 mm wider than the nominal scaffold diameter.…”

“…Recently, Absorb bioresorbable vascular scaffolds were associated with higher risks of early and late stent thrombosis (ST), and adverse events compared with drug‐eluting stents (DESs) . Optimizing operators' skills, including the predilation, scaffold sizing, and postdilation (PSP) technique, could reduce the occurrence of adverse events after BRS implantation. This may apply to second‐generation DESs, which despite being thinner and incorporating biocompatible polymers to further reduce the risk of target lesion failure (TLF), are associated with occurrence of late events, including restenosis and thrombosis .…”

First‐in‐man study of a thinner‐strut sirolimus‐eluting bioresorbable scaffold (FUTURE‐I): Three‐year clinical and imaging outcomes

“…Bioresorbable scaffolds (BRS) were developed to address the limitations of metallic drug‐eluting stents (DES), such as vascular inflammation, neoatherosclerosis, and side branches jailing . However, the unexpectedly high incidence of late thrombosis comparing with contemporary DES prompted withdrawal of the Absorb BVS (Abbott Vascular, Santa Clara, California) from the market .…”

“…Bioresorbable scaffolds (BRS) were developed to address the limitations of metallic drug‐eluting stents (DES), such as vascular inflammation, neoatherosclerosis, and side branches jailing . However, the unexpectedly high incidence of late thrombosis comparing with contemporary DES prompted withdrawal of the Absorb BVS (Abbott Vascular, Santa Clara, California) from the market . Currently, the most compelling explanation appears to be strut thickness (>150 μm), which is almost twice that of currently metallic stents resulting in greater protrusion space and turbulence flow, delayed reendothelialization, and unfavorable dismantling during the resorption process .…”