BACKGROUND: In patients with severe aortic stenosis at increased risk for surgery, self-expanding transcatheter aortic valve replacement (TAVR) is associated with improved 2-year survival compared with surgery. OBJECTIVES: This study sought to determine whether this clinical benefit was sustained over time. METHODS: Patients with severe aortic stenosis deemed at increased risk for surgery by a multidisciplinary heart team were randomized 1:1 to TAVR or open surgical valve replacement (SAVR). Three-year clinical and echocardiographic outcomes were obtained in those patients with an attempted procedure. RESULTS: A total of 797 patients underwent randomization at 45 U.S. centers; 750 patients underwent an attempted procedure. Three-year all-cause mortality or stroke was significantly lower in TAVR patients (37.3% vs. 46.7% in SAVR; p = 0.006). Adverse clinical outcome components were also reduced in TAVR patients compared with SAVR patients, including all-cause mortality (32.9% vs. 39.1%, respectively; p = 0.068), all stroke (12.6% vs. 19.0%, respectively; p = 0.034), and major adverse cardiovascular or cerebrovascular events (40.2% vs. 47.9%, respectively; p = 0.025). At 3 years aortic valve hemodynamics were better with TAVR patients (mean aortic valve gradient 7.62 ± 3.57 mm Hg vs. 11.40 ± 6.81 mm Hg in SAVR; p < 0.001), although moderate or severe residual aortic regurgitation was higher in TAVR patients (6.8% vs. 0.0% in SAVR; p < 0.001). There was no clinical evidence of valve thrombosis in either group. CONCLUSIONS: Patients with severe aortic stenosis at increased risk for surgery had improved 3-year clinical outcomes after TAVR compared with surgery. Aortic valve hemodynamics were more favorable in TAVR patients without differences in structural valve deterioration. (Safety and Efficacy Study of the Medtronic CoreValve(®) System in the Treatment of Symptomatic Severe Aortic Stenosis in High Risk and Very High Risk Subjects Who Need Aortic Valve Replacement; NCT01240902).