[1] Univ Iowa, Dept Internal Med, Div Cardiovasc Med, Carver Coll Med, Iowa City, IA 52242 USA
[2] Seoul Natl Univ Hosp, Dept Internal Med, Seoul, South Korea
[3] Seoul Natl Univ Hosp, Cardiovasc Ctr, Seoul, South Korea
[4] Chonnam Natl Univ, Chonnam Natl Univ Hosp, Heart Ctr, Dept Internal Med,Div Cardiol,Med Sch, Gwangju, South Korea
[5] Sungkyunkwan Univ, Samsung Med Ctr, Heart Vasc Stroke Inst, Dept Internal Med,Sch Med,Div Cardiol, Seoul, South Korea