James H. O'Keefe, Jr., M.D., is Director of the Charles and Barbara Duboc Cardio Health and Wellness Center, Co-director of the Haverty CardioMetabolic Center of Excellence at the Saint Luke's of Kansas City, Mid America Heart Institute and Professor of Medicine at the University of Missouri-Kansas City in Kansas City, MO. His postgraduate training included a cardiology fellowship and internal medicine residency at Mayo Clinic in Rochester, Minnesota. Dr. O'Keefe has contributed more than 400 articles to the medical literature, and he has authored numerous books on cardiovascular medicine. He lectures nationally and internationally on diet, exercise, supplements, and drug therapy for cardiovascular health, well-being, and longevity. He has co-authored, with his wife Joan, the best-selling consumer health books Let Me Tell You a Story and The Forever Young Diet and Lifestyle. Dr. O'Keefe is actively involved in patient care, research, and education. He is regularly listed among the Top Doctors and has been recognized as one of the Most Influential Doctors in America. He has done multiple TEDx Talks that have been viewed millions of times. Dr. O'Keefe is also editor-in-chief of "From the Heart" newsletter, which goes out to 250,000 homes and offices twice yearly.Stephen C. Hammill, MD, FACC, FHRS, is Emeritus Professor of Medicine and former William S. and Ann Atherton Professor of Cardiology at the Mayo Clinic College of Medicine, Rochester, Minnesota; Past-President of the Heart Rhythm Society; and one of the world's leading authorities on ECG interpretation and electrophysiology. He joined the staff at Mayo Clinic in 1981, where he served as Director of the ECG Laboratory for 26 years and Director of the Electrophysiology Laboratory for 18 years.Dr. Hammill has been teaching ECG interpreration to physicians and trainees for over 35 years, and he taught the ECG section of the distinguished Mayo Clinic Cardiovascular Board Review Course for 8 years and was a member of the American Board of Internal Medicine Cardiac Electrophysiology Recertification and Certification Test Writing Committee for 9 years. He was President of the Heart Rhythm Society and recipient of the Society's Distinguished Service Award; first ACC Chapter President for Minnesota; and member of the ACC Board of Governors.Dr. Hamill has published extensively on heart rhythm disorders, contributing more than 320 scientific manuscripts, books, book chapters, and review articles. He has also been a member of the Editorial Board of national and international medical journals, including Heart Rhythm, Journal of Cardiac Electrophysiology, and Journal of Electrocardiography. Dr. Hammill received the Mayo Clinic Henry Plummer Distinguished' Physician Award, the Mayo Clinic Distinguished Clinician Award, and the Distinguished Teaching Award.Mark S. Freed, MD, FACC, is a cardiologist in Chicago, Illinois, and Founder and former President and Editor-in-Chief of Physicians' Press, original publisher of The Complete Guide to ECGs. Dr. Freed is a prolific author, having authored and/or edited more than 25 medical reference texts, 50 editions, and 500 chapters, including The Manual of Interventional Cardiology, Essentials of Cardiovascular Medicine, The Complete Guide to ECGs, The ECG Criteria Book, and Acute Coronary Syndrome Essentials. He has also contributed numerous research articles to the medical literature. During his 17-year tenure at the helm of Physicians' Press, more than 1.8 million medical reference texts were distributed worldwide. Dr. Freed is Founder and Editor-in-Chief of the Physician-Patient Partnership Program, former Medical Director and Principal Investigator at MEDEX Healthcare Research, Inc., in Chicago, IL, and Founder and former Chairman of The Magic of Children Foundation. He is also an invited speaker and frequent radio guest on cardiovascular health and other health topics. Dr. Freed is committed to providing physicians and trainees with the most practical resources aimed at improving ECG interpretation skills and patient care.