[1] Sungkyunkwan Univ, Sch Med, Samsung Med Ctr, Dept Internal Med,Heart Vasc Stroke Inst, Seoul, South Korea
[2] Natl Maritime Med Ctr, Chang Won, South Korea
[3] Seoul Natl Univ Hosp, Dept Internal Med, Seoul, South Korea
[4] Seoul Natl Univ Hosp, Cardiovasc Ctr, Seoul, South Korea
[5] Minist Hlth & Welf, Naju Natl Hosp, Dept Internal Med, Naju, South Korea
[6] US FDA, Div Biostat, Ctr Devices & Radiol Hlth, Silver Spring, MD USA