[1] Beth Israel Deaconess Med Ctr, Div Cardiovasc, Boston, MA 02215 USA
[2] Harvard Univ, Clin Res Inst, Boston, MA 02115 USA
[3] Royal Brompton Hosp, Clin Trials & Evaluat Unit, London SW3 6LY, England
[4] Lenox Hill Hosp, New York, NY 10021 USA
[5] Duke Univ, Med Ctr, Durham, NC USA