Tissue coverage of a hydrophilic polymer-coated zotarolimus-eluting stent vs. a fluoropolymer-coated everolimus-eluting stent at 13-month follow-up: an optical coherence tomography substudy from the RESOLUTE All Comers trial

Abstract

Aims: To compare the tissue coverage of a hydrophilic polymer-coated zotarolimus-eluting stent (ZES) vs. a fluoropolymer-coated everolimus-eluting stent (EES) at 13 months, using optical coherence tomography (OCT) in an 'all-comers' population of patients, in order to clarify the mechanism of eventual differences in the biocompatibility and thrombogenicity of the devices.

Methods and results: Patients randomized to angiographic follow-up in the RESOLUTE All Comers trial (NCT00617084) at pre-specified OCT sites underwent OCT follow-up at 13 months. Tissue coverage and apposition were assessed strut by strut, and the results in both treatment groups were compared using multilevel logistic or linear regression, as appropriate, with clustering at three different levels: patient, lesion, and stent. Fifty-eight patients (30 ZES and 28 EES), 72 lesions, 107 stents, and 23 197 struts were analysed. Eight hundred and eighty-seven and 654 uncovered struts (7.4 and 5.8%, P= 0.378), and 216 and 161 malapposed struts (1.8 and 1.4%, P= 0.569) were found in the ZES and EES groups, respectively. The mean thickness of coverage was 116 ± 99 µm in ZES and 142 ± 113 µm in EES (P= 0.466). No differences in per cent neointimal volume obstruction (12.5 ± 7.9 vs. 15.0 ± 10.7%) or other areas-volumetric parameters were found between ZES and EES, respectively.

Conclusion: No significant differences in tissue coverage, malapposition, or lumen/stent areas and volumes were detected by OCT between the hydrophilic polymer-coated ZES and the fluoropolymer-coated EES at 13-month follow-up.

Figure 1

Categories of apposition. Optical coherence tomography cross-sections showing examples of struts in the three different categories of apposition: well-apposed (white arrows), incomplete stent apposition (orange arrows), and; NASB, non-apposed side branch.

Figure 2

Coverage. Optical coherence tomography cross-sections showing examples of covered (white arrows) and non-covered struts (red arrows).

Figure 3

Spread-out-vessel graph, illustrative cases. The X-axis represents the distance from the distal edge of the stent to the strut; the Y-axis represents the angle where the strut is located in the circular cross-section with respect to the centre of gravity of the vessel. The result is a graphic representing the spatial distribution of the non-covered struts (red spots) along the stent, as if it had been cut along the reference angle (0°) and spread out on a flat surface.

Figure 4

Spread-out-vessel graphics showing non-covered struts of the 109 stents and corresponding overlaps analysed at 13 months. The graphic summarizes the spatial distribution of non-coverage and its clustering at the four considered levels (allocation to treatment, patient, lesion, and stent).