Jason S Bradfield1, Kalyanam Shivkumar2. 1. UCLA Cardiac Arrhythmia Center, 100 medical Plaza, Suite 660, Los Angeles, CA 90095, USA. Electronic address: JBradfield@mednet.ucla.edu. 2. UCLA Cardiac Arrhythmia Center, 100 UCLA Medical Plaza, Suite 660, Los Angeles, CA 90095, USA. Electronic address: kshivkumar@mednet.ucla.edu.