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Sirolimus-eluting cobalt alloyed stents in treating patients with coronary artery disease: six-month angiographic and one-year clinical follow-up result. A prospective, historically controlled, multi-center clinical study.

BACKGROUND
The emergence of drug-eluting stents (DES) has dramatically reduced the incidence of in-stent restenosis. This study was conducted to evaluate the safety and efficacy of sirolimus-eluting cobalt-chrome stents (Firebird 2) for treating patients with coronary artery disease.


METHODS
Sixty-seven patients with de novo or non-stented restenostic coronary lesions were chosen to receive the Firebird 2 stent as the final treatment (Firebird 2 group). Another 49 consecutive patients were implanted with bare cobalt alloyed stents (Driver, Medtronic) within the previous six months and served as historical controls (control group). Baseline clinical characteristics, angiographic features, procedural results, 30-day, 6-month and 12-month clinical follow-up regarding the occurrence of major adverse cardiac events (MACE), as well as the primary endpoint of late lumen loss at 6-month angiographic follow-up were compared between the two groups.


RESULTS
The demographic characteristics were similar between the two groups despite more patients in the Firebird 2 group who underwent previous percutaneous coronary intervention (22.4% vs 8.2%, P = 0.0418) and who had diabetes mellitus (29.9% vs 12.2%, P = 0.0253). In the Firebird 2 group, the mean diameter of the reference vessel was smaller ((2.79 +/- 0.46) mm vs (2.98 +/- 0.49) mm, P = 0.0175) and more stents were implanted for each lesion (1.28 +/- 0.52 vs 1.10 +/- 0.30, P = 0.0060). Other angiographic, procedural results and the device success rate were similar between the two groups. The MACE rate at 30-day and 3-month was the same, but significantly fewer MACE occurred in the Firebird 2 group at 6- and 12-month follow-up (1.5% vs 12.2% at 6 month, P = 0.0168; 1.5% vs 26.5% at 12 month, P < 0.0001). The primary endpoint of late lumen loss at 6-month angiographic follow-up was significantly reduced in the Firebird 2 group (in-stent: (0.05 +/- 0.09) mm vs (0.98 +/- 0.61) mm; in-segment: (0.05 +/- 0.18) mm vs (0.72 +/- 0.59) mm; P < 0.0001) than the control group. One patient in the Firebird 2 group had in-segment restenosis (1.3%) while the rate in the control group (38.1%) was significantly higher, P < 0.0001. Intravascular ultrasound examination was performed in 70.1% of patients in the Firebird 2 group and revealed that the percentage of volumetric obstruction was (1.26 +/- 1.05)%. No stent thrombosis was observed in either group at 12-month follow-up.


CONCLUSION
The Firebird 2 sirolimus-eluting cobalt alloyed stent is safe and feasible in treating patients with coronary artery disease.