[1] Odense Univ Hosp, Dept Cardiol, DK-5000 Odense C, Denmark
[2] Univ Oslo, Fac Med, N-0316 Oslo, Norway
[3] Univ Oslo, Aker Univ Hosp, Div Cardiol, N-0316 Oslo, Norway
[4] Univ Oslo, Rikshosp, Dept Cardiovasc Med, N-0027 Oslo, Norway
[5] Massachusetts Gen Hosp, Div Cardiol, Boston, MA 02114 USA