title: Invited Commentary.
authors.affiliation: Duke University School of Medicine, 8 Searle Center Dr, Durham, NC 27710. Electronic address: j.matthew.brennan@dm.duke.edu.
authors.forename: J Matthew
authors.initials: JM
authors.lastname: Brennan
mesh_terms: D001021:Aortic Valve / Q000601:surgery*; D005260:Female; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis / Q000706:statistics & numerical data*; D019918:Heart Valve Prosthesis Implantation / Q000401:mortality*; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D008297:Male