Optical coherence tomography tissue coverage and characterization at six months after implantation of bioresorbable scaffolds versus conventional everolimus eluting stents in the ISAR-Absorb MI trial

Purpose: Data regarding vessel healing by optical coherence tomography (OCT) after everolimus-eluting bioresorbable scaffolds (BRS) or everolimus-eluting metallic stent (EES) implantation in acute myocardial infarction (AMI) patients is scarce. We compared OCT findings after BRS or EES implantation in patients with AMI enrolled in a randomized trial.

Methods: In ISAR-Absorb MI, AMI patients were randomized to BRS or EES implantation, with 6-8 month angiographic follow-up. This analysis includes patients who underwent OCT during surveillance angiography. Tissue characterization was done using grey-scale signal intensity analysis. The association between OCT findings and target lesion failure (TLF) at 2 years was investigated.

Results: OCT was analyzed in 103 patients (2237 frames, 19,827 struts) at a median of 216 days post-implantation. Of these, 70 were treated with BRS versus 32 with EES. Pre-(92.8 vs. 68.7%, p = 0.002) and post-dilation (51.4 vs. 12.5%, p < 0.001) were more common in BRS as compared to EES. Strut coverage was higher in BRS vs. EES (97.5% vs. 90.9%, p < 0.001). Mean neointimal thickness was comparable in both groups [85.5 (61.9, 124.1) vs. 69.5 (32.7, 127.5) µm, respectively, p = 0.20]. Mature neointimal regions were numerically more common in BRS (43.0% vs. 24.6%; p = 0.35); this difference was statistically significant in ST-elevation myocardial infarction patients (40.9% vs. 21.1%, p = 0.03). At two-years, 8 (7.8%) patients experienced TLF. Mean neointimal area [0.61 (0.21, 1.33) vs. 0.41 (0.11, 0.75) mm2, p = 0.03] and mean neointimal coverage [106.1 (65.2, 214.8) vs. 80.5 (53.5, 122.1) µm, p < 0.01] were higher, with comparable tissue maturity, in lesions with versus without TLF.

Conclusions: In selected patients who underwent OCT surveillance 6-8 months after coronary intervention for AMI with differing implantation characteristics depending on the device type used, vessel healing was more advanced in BRS compared with EES, particularly in the STEMI subgroup.