Received April 22, 1998; revision received August 26, 1998; accepted September 25, 1998.From the Department of Medicine, Section of Cardiology, Baylor College of Medicine at Houston, Tex.Guest Editor for this article was A. Jamil Tajik, MD, Mayo Clinic, Rochester, Minn.Correspondence and reprint requests to Sherif F. Nagueh, MD, Section of Cardiology, Baylor College of Medicine, SM1246, 6550 Fannin, Houston, TX 77030. E-mail sherifn@bcm.tmc.edu.