[1] Aintree Univ Hosp NHS Fdn Trust, Aintree Cardiac Ctr, Liverpool L9 7AL, Merseyside, England
[2] Duke Univ, Med Ctr, Durham, NC USA
[3] Brigham & Womens Hosp, Boston, MA 02115 USA
[4] Rigshosp, Dept Cardiol, DK-2100 Copenhagen, Denmark
[5] Sahlgrens Univ Hosp, Gothenburg, Sweden
[6] Univ Glasgow, Glasgow, Lanark, Scotland
[7] Osped Res Ctr, Assoc Nazl Med Cardiol, Florence, Italy