Original title: First Serial Assessment at 6 Months and 2 Years of the Second Generation of Absorb Everolimus-Eluting Bioresorbable Vascular Scaffold A Multi-Imaging Modality Study. Reference: John Ormiston et al. Circ Cardiovasc Interv. 2012;5:620-632.
The first bioabsorbable stents eluting everolimus showed a 6-month delayed recoil resulting in late lumen loss of 0.44 mm, (intermediate between a metal stent and Xience V). To improve this, the emerging platform was modified and the second-generation everolimus Absorb emerged.
From 101 patients in cohort B, (cohort A received the 1st generation), 45 were followed with quantitative angiography, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) at 6 and 24 months. The rest of cohort B was also followed invasively, but at 12 and 36 months. At follow-up to 2 years, there were 3 myocardial infarctions and 6 revascularization of target lesion which gave a total of 9% MACE. There was no stent thrombosis.
Neointimal hyperplasia detected by IVUS of 0.25 mm2 to 2 years was minimal but with a significant increase between 6 months and 2 years. OCT struts were still present after 2 years but with reabsorption signs, (complete reabsorption occurs during the 3rd year). Incomplete apposition basally detected in 11 stents was observed after 1-2 years. The increased luminal diameter after nitroglycerin administration shows recovery vasomotor tone in the treated area.
Commentary
This device is already in the 2nd generation before reaching normal practice and probably still needs modifications but the results are very promising. The progression of neointimal proliferation between 6 months and 2 years shown by IVUS is not important in absolute numbers but evidence that the healing process continues over time beyond what was originally thought. We must await the results of the study Absorb 2 which compares Xience versus Absorb but even though this never reached metallic platforms, the fact that after three years the artery appears “de novo” both anatomically and functionally does not seem to be a huge advantage. The restoration of endothelial function response to medical treatment would facilitate, without prosthesis at the injury site, a new revascularization by any method which would be simpler.
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