For treatment of coronary heart disease, recent studies have shown everolimus-eluting Absorb (Abbott Vascular, Abbott Park, Illinois) bioresorbable scaffolds to be comparably effective to everolimus-eluting metallic stents one year after surgery.
Researchers are heralding bioresorbable vascular scaffolds as the next development in the treatment of coronary heart disease. “Theoretically, [they] may provide superior long-term results compared with permanent metallic drug-eluting stents,” wrote study researcher Takeshi Kimura, MD, PhD, from the Department of Cardiovascular Medicine at Kyoto University Hospital, and colleagues.1
Metallic stents were a revolutionary improvement in the 1980s over balloon angioplasty (developed in 1977 by Andreas Gruentzig), providing a solution to acute vessel occlusion and reducing rates of restenosis.2 The introduction of drug-eluting stents in 2001 was an even further advancement, lowering rates of restenosis and late stent thrombosis. However, leaving a metallic stent in the blood vessels can create its own set of problems, such as increased risk of late and very late stent thrombosis, as well as persistent inflammatory reaction around the stent struts.
A bioresorbable vascular scaffold “would prevent acute vessel closure and recoil while transiently eluting an antiproliferative drug to counteract the constrictive remodeling and excessive neointimal hyperplasia.” 2 After a predetermined time period, the scaffold would be resorbed, completely integrated into the vessel wall, and infiltrated by functional smooth muscle cells. This would reduce the chances of stent thrombosis because drug elution and scaffolding would only be present temporarily, so no potential triggers for stent thrombosis such as nonendothelialized struts or drug polymers would remain long term. The removal of the rigid stent casing could also facilitate return of vessel vasomotion, adaptive shear stress, late luminal enlargement, and late expansive remodeling.
In the ABSORB Japan randomized trial, 400 patients undergoing coronary stent implantation in Japan were randomly assigned in a 2:1 ratio to treatment with the Absorb everolimus-eluting bioresorbable vascular scaffold or the everolimus-eluting metallic stent XIENCE Prime/Xpedition CoCr-EES (Abbott Vascular, Abbott Park, Illinois). The primary end point for the study was target lesion failure or ischemia-driven target lesion revascularization at 1 year; the major secondary end point was angiographic in-segment late lumen loss at 13 months.
Within 1 year, target lesion failure occurred in 11 out of 265 patients receiving the scaffold and in 5 out of 133 patients receiving the metallic stent, demonstrating noninferiority of the bioresorbable scaffold. There were no significant differences in any of the end points at 1 year between the two groups.
Within 13 months, late lumen loss was 0.13 ± 0.30 mm in patients with the scaffold and 0.12 ± 0.32 mm in patients with the metallic stent, also demonstrating noninferiority of bioresorbable scaffolds to drug-eluting metallic stents.
The authors state that “long-term follow-up is required to determine whether the temporary scaffolding properties of bioresorbable scaffolds are associated with similar or improved outcomes compared with a permanent metallic drug-eluding stent.” However, they conclude that the 1-year and 13-month comparability of bioresorbable scaffolds to drug-eluting metallic stents supports the feasibility of bioresorbable scaffolds potentially improving long-term outcomes for patients with coronary heart disease undergoing percutaneous coronary intervention.
Disclosures: Several authors are employees of Abbott Vascular US and Japan.
1. Kimura T, Kozuma K, Tanabe K, et al. A randomized trial evaluating everolimus-eluting Absorb bioresorbable scaffolds vs. everolimus-eluting metallic stents in patients with coronary artery disease: ABSORB Japan. Eur Heart J. 2015.doi:10.1093/eurheartj/ehv435.
2. Onuma Y, Serruys PW. Bioresorbable scaffold: the advent of a new era in percutaneous coronary and peripheral revascularization? Circulation. 2011;123:779-797.doi:10.1161/CIRCULATIONAHA.110.971606.
3. Patel N, Banning AP. Bioresorbable scaffolds for the treatment of obstructive coronary artery disease: the next revolution in coronary intervention? Heart. 2013;99(17):1236-1243. doi: 10.1136/heartjnl-2012-303346.