The Clinical and Angiographic analysis with a Cobalt Alloy Coronary Stent (Driver) (CLASS) study was a prospective, nonrandomized, multicenter study designed to assess the safety and efficacy of a cobalt-chromium alloy-based stent in patients with stable or unstable angina pectoris. A total of 203 lesions were treated in 202 enrolled patients. The percentage of major adverse cardiac event-free patients was 87.6% (177 of 202) at 6 months (primary safety end point; major adverse cardiac events were defined as death, myocardial infarction, emergency bypass surgery, or target lesion revascularization [percutaneous transluminal coronary angioplasty or coronary artery bypass grafting]). The angiographic success rate (primary efficacy end point) was 100%, and the procedural success rate was 98%. The binary in-stent restenosis rate at 6 months was 12.6%. Our results have demonstrated that the Driver cobalt-chromium alloy stent can be used with a low 6-month incidence of major adverse cardiac events, a low 6-month binary restenosis rate, and high angiographic and procedural success rates. The Medtronic Driver stent (Medtronic Vascular, Santa Rosa, California) is composed of a cobalt-chromium alloy and is similar in design to the Medtronic S7 stent. The design is based on elements 1.0 mm in length with an elliptical-rectangular strut cross section and a strut thickness of 0.0036 in. (91 m). The cobalt-chromium alloy has superior mechanical properties compared with traditional 316L stainless steel, including greater strength and increased density. These properties have allowed the development of stents with thinner struts, offering increased flexibility and ease of delivery, without compromising radial strength or radiopacity. The strut thickness has been shown to be an important determinant of the long-term restenosis rate. [1][2][3][4] This prospective, nonrandomized, multicenter study was designed to assess the safety and efficacy of the Medtronic Driver stent.• • • Patients with clinical evidence of stable or unstable angina pectoris, or positive functional study findings, with a planned percutaneous transluminal coronary angioplasty procedure of a single de novo lesion in a native coronary artery were considered for inclusion. Lesions (Յ13 mm) situated in a major coronary artery or major branch with estimated stenosis of 50% to 100% and a diameter suitable for implantation of a single stent with a diameter of 3.0 to 4.0 mm were considered eligible for enrollment.Preprocedural antiplatelet therapy was administered according to local routine with the following recommendations: aspirin (minimum 75 mg/day) and ticlopidine (500 mg loading dose followed by 250 mg twice daily) or aspirin and clopidogrel (300 mg loading dose followed by 75 mg/ day). It was initiated Ն24 hours before the procedure or before the conclusion of the catheterization. Ticlopidine or clopidogrel were discontinued after 14 to 28 days, and aspirin (Ն75 mg/day) was maintained indefinitely (Ն6 months after implantation).After introduction of the arterial...