[1] Kangwon Natl Univ, Kangwon Natl Univ Hosp, Coll Med, Dept Thorac & Cardiovasc Surg, Chunchon, South Korea
[2] Univ Ulsan, Coll Med, Asan Med Ctr, Dept Thorac & Cardiovasc Surg, Seoul, South Korea
[3] CHA Univ, Dept Thorac & Cardiovasc Surg, CHA Bundang Med Ctr, Seoul, South Korea
[4] Yonsei Univ, Gangnam Severance Hosp, Coll Med, Dept Thorac & Cardiovasc Surg, Seoul, South Korea