High incidence of thrombus formation at 18 months after paclitaxel-eluting stent implantation: Angioscopic comparison with sirolimus-eluting stent

Background Difference of neointimal formational pattern and incidence of thrombus formation between sirolimus-eluting stent (SES) and paclitaxel-eluting stent (PES) at 18 months after stent implantation has not previously been reported. Methods We retrospectively enrolled 35 event-free patients who received SES (15 patients, 18 stents) or PES (20 patients, 23 stents) implantation with 18-month follow-up coronary angioscopy. We divided our patients into SES or PES groups and compared neointimal coverage pattern and incidence of red mural thrombus formation between the 2 groups. Neointimal coverage grades were classified into 4 categories. Minimum neointimal coverage grade, maximum grade, and heterogeneity score were assessed in each stent. Heterogeneity score was calculated by subtracting minimum from maximum grade within one stent. Results Minimum neointimal coverage grade of PES was significantly lower than that of SES (0.70 ± 0.64 vs 1.33 ± 0.69, P = .005), whereas maximum grade was not significantly different (2.48 ± 0.73 vs 2.22 ± 0.73, P = .218). Heterogeneity score and incidence of red mural thrombus of PES were higher than those of SES (1.78 ± 0.80 vs 0.89 ± 0.76, P = .002 and 70% vs 11%, P < .001). Conclusions The present study revealed that PES shows more heterogeneous neointimal coverage and higher incidence of thrombus formation as compared with SES at 18 months after stent implantation.