1. From the Department of Cardiology (S.-Y.M., D.-W.P., Y.-H.K., J.-Y.L., S.-J.K., S.-W.L., C.W.L.), University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea; and Division of Biostatistics (S.-C.Y.), Center for Medical Research and Information, University of Ulsan College of Medicine, Seoul, Korea.