An everolimus-eluting bioresorbable scaffold produces a comparable success rate to an everolimus-eluting metallic stent in aiding patients with coronary artery disease, according to results from the ABSORB II trial presented Sept. 14 at TCT 2014, and simultaneously published in the Lancet. 

The trial presented the first randomized data on the everolimus-eluting bioresorbable scaffold, and was led by principal investigator Patrick Serruys, MD, FACC, Imperial College, UK, Erasmus University Medical Center, Rotterdam, the Netherlands. The trial looked at 501 subjects who were randomized two to one to either the everolimus-eluting bioresorbable scaffold (Absorb) or the everolimus-eluting metallic stent (Xience) at 46 sites in Europe and New Zealand.

Additional Resources TCT 2014 Meeting Coverage ABSORB II Trial Summary Presentation Slides

His team found that at one year, DoCE (cardiac death, TV-MI and TLR, Absorb: 4.8 percent vs. Xience: 3.0 percent, p=0.35), PoCE (all death, all MI and all revascularization, Absorb: 7.3 percent vs. Xience: 9.1 percent, p=0.47) and their components were similar between the two arms.

Additional results showed that acute gain by angiography and IVUS was significantly lower in the Absorb arm than in the Xience arm, (QCA, Absorb 1.15 ± 0.4 mm vs. Xience 1.46 ± 0.4 mm, p<0.001; IVUS, Absorb 2.9 ± 1.3 mm2, Xience 3.6 ± 1.3 mm2, p <0.001). The difference was not related to the acute recoil measured immediately after device implantation (0.19 mm for both), but could be attributed to the difference in pressure and nominal size of the balloon used during the post-implantation dilatation performed in a similar proportion (~60 percent) of patients in each arm, according to the investigators.

A comprehensive analysis also showed that three sets of myocardial biomarkers did not indicate any significant difference of myonecrosis despite differences in strut thickness and width of the two respective devices. However, results did show that peri-procedural MI rates based on WHO definition were 3.9 percent in the Absorb arm and 1.2 percent in the Xience arm (p=0.16) respectively. Applying more contemporary enzyme thresholds for MI criteria such as SCAI (CKMB >10 x ULN; 0.6 percent vs. 0.6 percent, p=1.0) or TUD (Troponin > 5 x ULN; 29.8 percent vs. 25.6 percent, p=0.33) did not disclose any difference between the two arms.

Finally, an assessment of exercise performance and angina status demonstrated comparable results, though a difference in nitrate use was observed at six months (17.8 percent vs. 26.7 percent, p=0.02) and 12 months (19.5 percent vs. 26.2 percent, p=0.09) in favor of the Absorb arm. The investigators conclude that the difference in the two arms’ cumulative rates (21.8 percent in the Absorb arm vs. 30.5 percent in the Xience arm, p=0.04, 16.4 percent vs 25.6 percent, p=0.015 if the first seven days are excluded) of angina according to AE reporting (recurrent or worsening angina) is a post-hoc, hypothesis generating observation that warrants further physiological and clinical investigation.

Keywords: Biomarkers, Coronary Restenosis, Immunosuppressive Agents, Dilatation, Sirolimus, Stents, Troponin

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