ABSORB II raises bioresorbable scaffold concerns
medwireNews: The first head-to-head trial of a bioresorbable versus a metal drug-eluting coronary stent suggests an increased rate of complications with the bioresorbable version.
And the study findings show “that the hypothesised advantages of bioresorbable stents were not readily detectable,” write Robert Byrne and Adnan Kastrati, from Deutsches Herzzentrum München in Germany, in a commentary that accompanies the study published in The Lancet.
When assessed 3 years after intervention, vasomotor reactivity in the stented segment, which was the primary endpoint, was no different between the study groups. The 335 patients assigned to receive the Absorb everolimus-eluting bioresorbable stent (Abbott Vascular, Santa Clara, California, USA) had a 0.047 mm increase in mean lumen diameter after intracoronary injection of nitrate while the 166 who received the Xience everolimus-eluting metallic stent (Abbott Vascular) had a 0.056 mm increase.
Improved vasomotion theoretically benefits late luminal loss, but this did not even meet the researchers’ criterion for noninferiority, at 0.37 mm in the Absorb group versus 0.25 mm in the Xience group.
And the Absorb group had worse outcomes than the Xience group for other angiographic variables, including minimum lumen diameter, percentage diameter stenosis, and in-device and in-segment binary restenosis.
There was also no difference between the groups in the proportion of patients who were free from angina, at 74% and 73%, respectively.
Furthermore, study author Patrick Serruys (The National Heart and Lung Institute, London, UK) and co-workers found a higher rate of device-related adverse clinical events in the Absorb group, driven by an increased rate of target vessel myocardial infarction, at 6% versus 1% in the Xience group. In addition, there were eight definite and one probable late or very late scaffold thromboses in the Absorb group versus none in the Xience group.
However, the study was not powered to detect difference in clinical endpoints, so Byrne and Kastrati stress that “it remains to be seen whether the adverse safety signal is a real finding.”
The researchers note that none of the patients with late or very late scaffold thrombosis were taking dual antiplatelet therapy; no cases occurred in patients who were, although they stress that the connection is “entirely speculative.”
But the commentators believe that it is important to define the role of dual antiplatelet therapy in patients with reabsorbable stents. “For although expectations regarding late performance have not been realised to date, the obvious advantage of a stent that disappears remains a goal worth pursuing.”
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