From the Heart Institute (S.-J.P., J.-M.A., Y.-H.K., D.-W.P., S.-H.Y., H.W.P., M.C., J.-Y.L., S.-J.K., S.-W.L., C.W.L., S.-W.P.) and Division of Biostatistics (S.-C.Y.), Center for Medical Research and Information, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea. (At 2015-03)
