Bioresorbable scaffold spurs greater vessel remodelling than metal stent
Use of a bioresorbable vascular scaffold (BVS) led to more expansive vessel remodelling than metallic drug-eluting stent (DES) at 3 years after implantation, with a greater increase in lumen and vessel areas, according to additional data from the ABSORB II* trial.
Initial data from the trial did not achieve its coprimary endpoints of “superiority in vasomotion and noninferiority in angiographic late luminal loss following implantation” of the Absorb BVS vs the Xience metallic DES.
The current analysis was based on intravascular image (IVUS) data of 383 lesions of 359 patients undergoing percutaneous coronary intervention (PCI) who were randomized 2:1 to receive either the Absorb BVS or the Xience metallic DES in the prospective, single-blind, multicentre ABSORB II trial. [J Am Coll Cardiol 2017;70:60-74]
At 3 years, increase in both the mean vessel and lumen areas was significantly greater in lesions treated with the BVS compared with the metallic stents (6.7 percent vs 2.9 percent; p=0.003 for mean vessel area and 1.4 percent vs -1.9 percent; p=0.031 for mean lumen area).
Independent predictors of late expansive remodelling in both arms included use of the BVS, adequate device expansion at an index of ≥0.8, greater arterial stretch (balloon-artery ratio >1.25), history of having PCI, higher LDL cholesterol level, and being female. A plaque necrotic core content >16.7 percent before the procedure was also independently predictive of expansive remodelling in the BVS arm.
“These hypotheses generating data could support links among a scaffold-specific implantation strategy, expansive remodelling, and concurrent lumen enlargement,” wrote Drs Habib Samadi and Parham Eshtehardi of Emory University School of Medicine in Atlanta, Georgia, US, and Dr Adma Brown from Monash Cardiovascular Research Centre in Clayton, Australia, in an editorial, noting that the technique for BVS deployment has evolved from a relatively conservative to a more aggressive strategy currently recommended. [J Am Coll Cardiol 2017;70:75-77]
While luminal expansion may be atheroprotective against further plaque progression, accelerated expansive remodelling may lead to a higher risk of very late scaffold thrombosis due to acquired malapposition of the device, according to Samadi and colleagues.
“Whether the observed expansive remodelling after BVS implantation carries with it the adverse features associated with expansive remodelling seen in de novo atherosclerosis is also unclear,” wrote Samadi and co-authors.
“The balance between such potential ongoing risk and the benefit of vascular restoration after BVS degradation may be dependent on the intensity of secondary prevention strategies. Thus, long-term data are required to fully assess the prognostic significance of expansive remodelling observed following BVS implantation,” they continued.
According to the researchers, IVUS data were not available for the entire ABSORB II cohort, which poses a major limitation for the study.
“As the investigators acknowledge, it is quite possible that patients in whom serial IVUS data were unavailable were those with underexpansion, tortuosity, or angulation, precisely the cohort that would be important to investigate,” commented Samadi and colleagues.
“However, data from the present study keep the promise of vascular restoration alive,” they added.