Dr. Packer is internationally known in Cardiac Electrophysiology. He is currently at the Intermountain Medical Center. He was the past John M. Nasseff, Sr., Professor in Cardiovascular Diseases, at Mayo Clinic Rochester, and was the Director of the Translational Electrophysiology Research Laboratory.  He received his MD degree at the University of Utah and completed an internship, residency and fellowship at Duke University, where he was on staff before coming to Mayo. His honors and awards include the ACC 2019 Distinguished Scientist Award (Translational), the Distinguished Service Award from Brigham Young University, the Haskel Schiff Award in Internal Medicine from Duke University, the Eric Prystowsky Advocate for Patients Award, and a variety of Visiting Professorship awards.

Dr. Packer is active in the Heart Rhythm Society where he is a past president and member of the Board of Trustees. He has been active in the American Heart Association and the American College of Cardiology. He has served/currently serves on editorial boards for the Circulation Arrhythmia & Electrophysiology, American Heart Journal, Heart Rhythm journal, and the (EP) Journal of the American College of Cardiology. He also has served on multiple National Heart, Lung, and Blood Institute work groups on atrial fibrillation, ablation and planning for future NIH studies.

Dr. Packer has been an active teacher and mentor, and also lectures widely on cardiac arrhythmias. He has written or co-authored more than 420 publications and 664 abstracts. He has lectured extensively in national and international meetings, giving over 1,650 invited lectures in 41 countries.  He has served on the executive committee of a number of NIH multicenter randomized clinical trials, Including the MUSTT, SCD-HeFT, and HAT Trials.  Dr. Packer is also the International Principal Investigator of the recently reported NIH CABANA Trial. In this capacity he led the consortium of centers directing the trial. He is the PI of the Thermedical VT Needle Electrode study, and on the Executive Committee of the LESS VT Study.

Dr. Packer is a Clinician Scientist.  His translational work focuses on the mechanisms and ablation of atrial fibrillation and other cardiac arrhythmias, autologous fibroblast modulation of electrical impulse propagation in the heart, and the development of carbon particle catheter-free ablation of arrhythmias.  His clinical work investigates 4/5 dimensional integrated image-guided ablation, and the development of new energy sources for the modification of cardiac tissue.   His work has been funded in part by private foundations, the American Heart Association, and the NIH.  A key part of his research is the development of the US Catheter Free Particle Therapy Ablation Program. He is also the PI of the Extracorporeal Particle Therapy Ablation Using Proton and Carbon Beams, that is currently under way. Dr. Packer holds 9 US and European patents in the development of intracardiac ultrasound, 4/5D imaging, and particle therapy ablation.