[1] Brigham & Womens Hosp, Boston, MA 02115 USA
[2] Cardiac Ctr Lousisiana, Shreveport, LA USA
[3] Rigshosp, DK-2100 Copenhagen, Denmark
[4] Assoc Nazl Med Cardiol Hosp Res Ctr, Florence, Italy
[5] Duke Univ, Med Ctr, Duke Clin Res Inst, Durham, NC USA
[6] Western Infirm & Associated Hosp, Glasgow, Lanark, Scotland