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ABSORB Japan: BVS, EES yield similar vessel healing at 2 years
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At 2 years after implantation, a fully bioresorbable vascular scaffold resulted in numerically higher rates of target lesion failure vs. a cobalt-chromium everolimus-eluting stent, but this difference was not statistically significant, according to findings from the ABSORB Japan trial.
Imaging findings were similar between the two devices, according to the researchers.
Researchers randomly assigned 400 patients on a 2:1 basis to treatment with a bioresorbable vascular scaffold (BVS; Absorb, Abbott Vascular; n = 266) or a cobalt-chromium everolimus-eluting stent (CoCr-EES; Xience Prime/Xpedition, Abbott Vascular; n = 134). An imaging substudy analyzed 125 patients who were randomly a prespecified subgroup for serial follow-up on OCT, occurring after the procedure, at 2 years and at 3 years.
The primary endpoint was TLF, defined as a composite of cardiac death, target vessel MI or ischemia-driven target lesion revascularization. The two major imaging endpoints included a nitrate-induced vasoreactivity test on angiography at the 2-year follow-up, and OCT measurement of changes in average lumen area from postprocedure to 2 years. The researchers counted 2-year events up to 758 days.
TLF similar
According to the researchers, at 2 years, clinical follow-up was available for 391 patients (98%). Nearly half of these patients were being treated with dual antiplatelet therapy (BVS, 52.3%; CoCr-EES, 50.7%; P = .78). There was no significant difference in 2-year TLF rates between the BVS and the CoCr-EES arms (BVS, 7.3%; CoCr-EES, 3.8%; P = .18).
The numerically higher rate of TLF in the BVS group was mainly attributable to a higher rate of ischemia-driven TLF, as well as target vessel MI, but the rate of all TLR was comparable between the two arms, the researchers wrote. The rates of definite or probable stent thrombosis were 3.1% in the BVS arm vs. 1.5% in the CoCr-EES arm (P = .51).
Between 1 and 2 years of follow up, four patients from the BVS group had MI (1.6%; two non–Q-wave MI and two Q-wave MI); these cases were associated with very late scaffold/stent thrombosis that occurred between 494 and 679 days after the index procedure.
Conversely, the researchers wrote, no very late scaffold/stent thrombosis was observed in the CoCr-EES arm.
Uniform tissue coverage
At 2 years, OCT showed uniform tissue coverage in most lesions in the BVS and the CoCr-EES arms. Stent and scaffold dimensions were stable 2 years after implantation, but a trend was observed toward greater neointimal growth with the BVS vs. the CoCr-EES. This resulted in smaller mean and minimum flow area in the BVS arm vs. the CoCr-EES arm, the researchers wrote, which was in keeping with the smaller in-device minimum lumen diameter by quantitative coronary angiography. OCT demonstrated complete vessel healing in both the BVS and CoCr-EES arms. At the site of minimal scaffold/stent area, the tissue characteristics were similar in both arms, and most of the characterized tissues were heterogeneous.
Nearly complete strut coverage was achieved in both arms, with minimal areas of incomplete strut apposition, according to the researchers.
“Scarce data are available on midterm outcomes after implantation of a [BVS] in comparison with a [CoCr-EES],” they wrote. “In the ABSORB Japan randomized trial comparing BVS and CoCr-EES, vessel healing as assessed by [OCT] at 2 years was almost complete in both arms, with complete strut coverage and minimal strut malapposition.” – by Jennifer Byrne
Disclosure: The study was funded by Abbott Vascular. Some researchers report financial ties with Abbott Vascular. Please see the full study for a list of the researchers’ relevant financial disclosures.
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