[1] Massachusetts Gen Hosp, Cardiac Arrhythmia Serv, Cardiovasc Res Ctr, Boston, MA 02114 USA
[2] Harvard Univ, Sch Med, Boston, MA 02114 USA
[3] Mt Sinai Sch Med, Cardiovasc Inst, New York, NY 10029 USA
[4] Brigham & Womens Hosp, Div Prevent Med, Boston, MA 02446 USA
[5] Massachusetts Gen Hosp, Div Cardiol, Boston, MA 02114 USA