Optical coherence tomography analysis of strut coverage in biolimus- and sirolimus-eluting stents: 3-Month and 12-month serial follow-up

Background No randomized studies have been conducted to investigate serial changes in optical coherence tomography (OCT) analyses following implantation of biolimus-A9-eluting stents (BES) and sirolimus-eluting stents (SES). Methods A total of 60 patients fulfilling the study criteria were randomly assigned into BES (n = 30) and SES (n = 30) implantation groups. Serial OCT evaluation at post-procedure, 3- and 12-month follow-up was performed in 46 patients [BES (n = 22) and SES (n = 24)]. OCT analyses were compared according to the type of stents and the follow-up time intervals. The percentage of uncovered struts was defined as the ratio of uncovered struts to total struts in all cross-sections. The primary endpoint was the percentage change (Δ) of uncovered struts in the 3- and 12-month follow-up samples. Results The percentage of uncovered struts at the 3-month time period was not significantly different in the BES and SES groups; the median value (interquartile range) was 14.7% (0.0-23.4) versus 8.6% (0.7-21.5) (p = 0.98), respectively. However, OCT at the 12-month follow-up showed a significantly lower percentage of uncovered struts [2.6% (0.8-5.6) versus 6.2% (1.7-14.7), (p = 0.028), respectively] without significant difference of neointimal thickness. BES showed a greater reduction of percentage Δ of uncovered struts from 3-12 months than that of SES [- 17.2 ± 14.5% versus - 7.7 ± 16.3%, respectively (p = 0.043)]. Conclusions Both drug-eluting stents showed a high percentage of incomplete strut coverage at 3 months. However, BES showed a significantly lower percentage of uncovered struts at 12 months compared to that of SES. This was achieved by superior strut coverage from 3 to 12 months.