The purpose of this study is to evaluate safety of reduction of thienopyridine treatment period to 3 months after implantation of Cobalt-Chromium everolimus-eluting Stents.

"Thienopyridine antiplatelet agents have markedly inhibited incidence of stent thrombosis, when they were combined with aspirin for 1 month after implantation of bare-metal stent (BMS). On the other hand, combination of aspirin with thienopyridine (dual antiplatelet therapy: DAPT) for more than 1 year after drug-eluting stent (DES) implantation is frequently used to prevent very late stent thrombosis in the current clinical practice. In the RESET study, which was carried out in clinical practice in Japan, DAPT was performed for at least 1 year in 90% of the patients. However, there has been no report showing that long-term thienopyridine treatment for at least 1 year reduces incidence of serious cardiovascular events, and large-scale observational studies or small-scale randomized comparative studies have demonstrated that thienopyridine treatment for 6 months or for at least 12 months does not reduce incidence of serious cardiovascular events. These results suggest that the optimal duration of DAPT after DES implantation may be shorter than 6 months.

With respect to Everolimus-eluting stent (EES), which is the most widely used DES in Japan, it has been associated with significantly lower incidence of early or late stent thrombosis compared with the first-generation DES and with BMS in large-scale observational study and randomized comparative studies and their meta-analyses.

Considering that long-term DAPT obviously increases hemorrhagic complications compared to Aspirin monotherapy, it is desirable to reduce the duration of DAPT as far as possible, if long-term DAPT is not effective in inhibiting the incidence of serious cardiovascular events. Moreover, long-term DAPT enormously increases medical expenses. In this study, we planned an exploratory multicenter study to evaluate incidences of cardiovascular events and bleeding events at 12 months after stent implantation using an EES (XIENCE Prime™), which is associated with low risk of stent thrombosis, when thienopyridine therapy is discontinued at 3 months after surgery.

Inclusion Criteria:

• Patients who received PCI using everolimus-eluting cobalt-chromium stents

Exclusion Criteria:

• Patients who had been implanted drug-eluting stents other than everolimus-eluting cobalt-chromium stents