1. From the Division of Cardiology, Korea University College of Medicine and Korea University Anam Hospital, Seoul, Republic of Korea (Y.G.K., J.-I.C., K.Y.B., D.Y.K., S.-K.O., K.-N.L., J.S., J.S.K., Y.-H.K.)
2. Department of Biostatistics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea (K.-D.H.).