[1] Univ Texas, Med Branch, Div Cardiol, Galveston, TX 77555 USA
[2] Temple Univ, Sch Med, Div Cardiol, Philadelphia, PA USA
[3] Northwestern Univ, Div Cardiol, Chicago, IL 60611 USA
[4] Blue Shield Calif, San Francisco, CA USA
[5] Univ Kentucky, Dept Surg, Lexington, KY USA
[6] Univ Alberta, Dept Med, Edmonton, AB, Canada