1 Electrophysiology Section, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
2 Department of Radiation Oncology, University of California, San Francisco, San Francisco, California.
3 Electrophysiology Section, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California. Electronic address: edward.gerstenfeld@ucsf.edu.