1 Cardiology Department, University of California San Diego, La Jolla, CA, USA.
2 Cardiovascular Center, Division of Cardiology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seoul, Korea.
3 Division of Cardiology, Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Korea.
4 Northwestern University Medical Center, Chicago, IL, USA.
5 Physics Department, University of California, Santa Barbara, CA, USA.
6 Physics Department, University of California San Diego, La Jolla, CA, USA.