Background: Resolute Zotarolimus-eluting stent (ZES-R) has extended drug elution period comparing to the existing ZES, thereby trying to suppress delayed arterial healing in more complex lesions and more difficult patients. Optical coherence tomography (OCT) has the virtue of high-resolution (≥ 10μm) which enables detection of the thin layer of neointimal hyperplasia (NIH) and malapposition. Thus, we tried to evaluate stent exposure and malapposition of ZES-R using OCT, comparing with Sirolimus-eluting stent (SES).
Method: Motorized OCT pullback (1 mm/s) was performed at 9-month follow-up to examine consecutively implanted 43 ZES-Rs (36 patients, 18 with acute coronary syndrome (ACS) and 18 with non-ACS) and 80 SESs (77 patients, 50 with ACS and 27 with non-ACS). NIH thickness inside each strut and percentage of NIH area in each cross section were measured.
Results: In total, 23855 struts in 3166-mm single-stented segments were analyzed. Overall, NIH thickness and percentage of NIH area were 120 ± 75 μm and 14.6 ± 9.7 %, respectively. Overall rates of exposed struts and exposed struts with malapposition were 8.18 % and 1.14 %, respectively. There were significant differences in NIH thickness (166±73 μm for ZES-R vs 96±63 μm for SES, p < 0.001) and percentage of NIH area (19.7±9.9 % for ZES-R vs 11.9±8.4 % for SES, p < 0.001) between two other stent groups. Rates of exposed struts and exposed struts with malapposition also revealed significant differences between two stent groups (rates of exposed struts, 4.35% for ZES-R vs 9.67% for SES, p=0.001; rates of exposed struts with malapposition, 0.19 % for ZES-R vs 1.51% for SES, p= 0.004). The intracoronary microthrombi were less frequently detected in ZES-R by OCT [2 (4.7%) in ZES-R vs 24 (30.0%) in SES, p=0.001].
Conclusion: ZES-R showed more NIH coverage than SES at 9-month after implantation. Exposed struts and malapposed struts were less frequently observed in ZES-R than in SES. Clinical implication of these OCT findings should be validated via further clinical studies.
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