1 Sparrow Thoracic and Cardiovascular Institute, Michigan State University, 1440 East Michigan Avenue; Suite 400, Lansing, MI 48912, USA. Electronic address: thakur@msu.edu.
2 Texas Cardiac Arrhythmia Institute, Center for Atrial Fibrillation at St. David's Medical Center, 1015 East 32nd Street, Suite 516, Austin, TX 78705, USA. Electronic address: andrea.natale@stdavids.com.