[1] Northwestern Univ, Bluhm Cardiovasc Inst, Clin Trials Unit, Feinberg Sch Med,Div Cardiol, Chicago, IL 60611 USA
[2] Orlando Reg Med Ctr Inc, Div Cardiol, Orlando, FL USA
[3] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90095 USA
[4] Brigham & Womens Hosp, Boston, MA 02115 USA
[5] Univ Rochester, Med Ctr, Rochester, NY 14642 USA