[1] Sungkyunkwan Univ, Sch Med, Samsung Med Ctr, Div Cardiol,Dept Med,Heart Vasc Stroke Inst, 81 Irwon Ro, Seoul 06351, South Korea
[2] Yonsei Univ, Dept Internal Med, Coll Med, Seoul, South Korea
[3] Seoul Natl Univ, Dept Internal Med, Coll Med, Seoul, South Korea
[4] Univ Ulsan, Asan Med Ctr, Dept Thorac Surg, Coll Med, Seoul, South Korea
[5] Univ Ulsan, Asan Med Ctr, Dept Internal Med, Coll Med, Seoul, South Korea