Sirolimus-eluting cobalt-chromium stents: two-year clinical results

Background Drug-eluting stents (DES) have been shown to significantly reduce clinical events and angiographic restenosis in the treatment of coronary artery disease (CAD). This study was conducted to assess the long-term efficacy and safety of the polymer-based sirolimus-eluting cobalt-chromium Firebird 2(TM) stents in the treatment of patients with CAD. Methods This first-in-man study using the Firebird 2(TM) stent is a prospective, historically-controlled multicenter clinical study, which enrolled 67 patients with CAD who were treated with the sirolimus-eluting cobalt-chromium stent (Firebird 2(TM), Microport Shanghai, Firebird 2 group), compared to another 49 patients treated with a bare cobalt alloy stent (Driver, Medtronic, control group). Continued 2-year clinical follow-up was performed after getting the initial 6-month angiographic and 1-year clinical follow-up. The incidence of major adverse cardiac events (MACE) including cardiac death, reinfarction and target lesion revascularization (TLR) and stent thrombosis were compared between the two groups. Results All patients in the Firebird 2 group (100.0%) and 48 patients in the control group (98.0%) completed the 2-year clinical follow-up. At the 1-year follow-up the use of the Firebird 2 stent was highly effective, resulting in a significant 94% decrease of TLR (26.5% in the control group and 1.5% in the Firebird 2 group, P<0.0001). A significant difference in TLR was maintained at 2-year follow-up, Firebird 2 group 1.5% and the control group 31.3% (P<0.0001). Between 1- and 2-year post-stenting, no more TLR occurred in the Firebird 2 group compared with two cases in the control group (P>0.05). There was a 1.5% incidence of MACE at 1- and 2-year follow-up in the Firebird 2 group, compared with 26.5% and 33.3% in the control group, respectively (all P<0.0001). The cumulative 1- and 2-year MACE free survival rates were 98.5% in the Firebird 2 group vs 73.5% and 66.7% in the control group (log rank P<0.0001). No case of stent thrombosis occurred during 2-year follow-up in the Firebird 2 group, compared with one case that suffered a definite stent thrombosis in the control group at 19-month post-stenting: this patient presented with unstable angina pectoris and was treated by balloon angioplasty. Conclusions Compared with the bare cobalt alloy stent, the Firebird 2(TM) sirolimus-eluting cobalt-chromium stent is safe and effective in treating patients with CAD. The use of this stent was associated with a sustained clinical benefit and significantly lower rate of TLR and MACE up to 2 years post-stenting.