1. From the Division of Cardiology, Department of Medicine (J.H., E.-K.K., J.-H.Y., S.-A.C., Y.B.S., J.-Y.H., S.H.C., H.-C.G., S.-H.L., J.-H.C.), Department of Emergency Medicine (J.-H.C.), and Department of Radiology (S.-M.K., Y.H.C.), Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; and Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN (J.K.O.).