Tomos Walters, PhD, MD

Cardiologist and electrophysiologist

Dr. Tomos Walters is a cardiologist who specializes in the heart's electrical system, or cardiac electrophysiology. He cares for adults with rhythm disorders that may arise from any chamber of the heart and cause fast, slow or irregular heartbeats. He seeks to individualize care and to establish clear and open communication with his patients.

Walters has extensive training in catheter ablation, a minimally invasive procedure that can restore a regular heartbeat by destroying a small area of malfunctioning heart tissue. He also specializes in implanting and managing cardiac rhythm devices. These range from standard pacemakers to advanced implantable devices that monitor electrical activity, defibrillate the heart if a life-threatening arrhythmia occurs or improve pumping efficiency in patients with heart failure.

Walters' research investigates the causes of persistent atrial fibrillation &nash; characterized by irregular or rapid heartbeats – as well as the factors that worsen symptoms and affect quality of life for patients with the condition. He also studies factors that lead to heart failure in patients with ventricular premature beats, or extra heartbeats that originate in the lower chambers.

Walters earned his medical degree as well as a doctorate from the University of Melbourne. He then completed a fellowship in electrophysiology at Royal Melbourne Hospital, where he studied under Jonathan Kalman, one of the leading electrophysiologists in Australia. He also completed a fellowship in electrophysiology at UCSF. He belongs to the American Heart Association, Royal Australasian College of Physicians and Cardiac Society of Australia and New Zealand.


Cardiac Electrophysiology and Arrhythmia Service
400 Parnassus Ave., Fifth Floor
San Francisco, CA 94143
Phone: (415) 353-2554
Fax: (415) 353-2528

Hours: Monday to Friday
8 a.m. – 5 p.m.

More about Tomos Walters


University of Melbourne, MD, PhD 2003


Royal Melbourne Hospital, Electrophysiology 2015
UCSF, Electrophysiology 2017

Selected Research and Publications

  1. McLellan AJA, Prabhu S, Voskoboinik A, Wong MCG, Walters TE, Pathik B, Morris GM, Nisbet A, Lee G, Morton JB, Kalman JM, Kistler PM. Isolation of the posterior left atrium for patients with persistent atrial fibrillation: routine adenosine challenge for dormant posterior left atrial conduction improves long-term outcome. Europace. 2017 Dec 01; 19(12):1958-1966.
  2. Pathik B, Kalman JM, Walters T, Kuklik P, Zhao J, Madry A, Sanders P, Kistler PM, Lee G. Absence of rotational activity detected using 2-dimensional phase mapping in the corresponding 3-dimensional phase maps in human persistent atrial fibrillation. Heart Rhythm. 2018 Feb; 15(2):182-192.
  3. Pathik B, Kalman JM, Walters T, Kuklik P, Zhao J, Madry A, Prabhu S, Nalliah C, Kistler P, Lee G. Transient Rotor Activity During Prolonged 3-Dimensional Phase Mapping in Human Persistent Atrial Fibrillation. JACC Clin Electrophysiol. 2018 Jan; 4(1):72-83.
  4. Walters TE, Kalman JM, Patel SK, Mearns M, Velkoska E, Burrell LM. Angiotensin converting enzyme 2 activity and human atrial fibrillation: increased plasma angiotensin converting enzyme 2 activity is associated with atrial fibrillation and more advanced left atrial structural remodelling. Europace. 2017 Aug 01; 19(8):1280-1287.
  5. Nazer B, Walters TE, Duggirala S, Gerstenfeld EP. Feasibility of Rapid Linear-Endocardial and Epicardial Ventricular Ablation Using an Irrigated Multipolar Radiofrequency Ablation Catheter. Circ Arrhythm Electrophysiol. 2017 Mar; 10(3).
  6. Janaswamy P, Walters TE, Nazer B, Lee RJ. Current Treatment Strategies for Heart Failure: Role of Device Therapy and LV Reconstruction. Curr Treat Options Cardiovasc Med. 2016 Sep; 18(9):57.
  7. Walters TE, Lee G, Spence S, Kalman JM. The effect of electrode density on the interpretation of atrial activation patterns in epicardial mapping of human persistent atrial fibrillation. Heart Rhythm. 2016 06; 13(6):1215-20.
  8. Walters TE, Nisbet A, Morris GM, Tan G, Mearns M, Teo E, Lewis N, Ng A, Gould P, Lee G, Joseph S, Morton JB, Zentner D, Sanders P, Kistler PM, Kalman JM. Progression of atrial remodeling in patients with high-burden atrial fibrillation: Implications for early ablative intervention. Heart Rhythm. 2016 Feb; 13(2):331-9.
  9. Prabhu S, McLellan AJ, Walters TE, Sharma M, Voskoboinik A, Kistler PM. Atrial structure and function and its implications for current and emerging treatments for atrial fibrillation. Prog Cardiovasc Dis. 2015 Sep-Oct; 58(2):152-67.
  10. Walters TE, Ellims AH, Kalman JM. The role of left atrial imaging in the management of atrial fibrillation. Prog Cardiovasc Dis. 2015 Sep-Oct; 58(2):136-51.
  11. Walters TE, Kalman JM. Human persistent atrial fibrillation is maintained by rotors: the jury is still out. Circ Arrhythm Electrophysiol. 2015 Jun; 8(3):517-9.
  12. McLellan AJ, Ling LH, Azzopardi S, Lee GA, Lee G, Kumar S, Wong MC, Walters TE, Lee JM, Looi KL, Halloran K, Stiles MK, Lever NA, Fynn SP, Heck PM, Sanders P, Morton JB, Kalman JM, Kistler PM. A minimal or maximal ablation strategy to achieve pulmonary vein isolation for paroxysmal atrial fibrillation: a prospective multi-centre randomized controlled trial (the Minimax study). Eur Heart J. 2015 Jul 21; 36(28):1812-21.
  13. Walters TE, Lee G, Spence S, Larobina M, Atkinson V, Antippa P, Goldblatt J, O'Keefe M, Sanders P, Kistler PM, Kalman JM. Acute atrial stretch results in conduction slowing and complex signals at the pulmonary vein to left atrial junction: insights into the mechanism of pulmonary vein arrhythmogenesis. Circ Arrhythm Electrophysiol. 2014 Dec; 7(6):1189-97.
  14. Walters TE, Teh AW, Spence S, Morton JB, Kistler PM, Kalman JM. Absence of gender-based differences in the atrial and pulmonary vein substrate: a detailed electroanatomic mapping study. J Cardiovasc Electrophysiol. 2014 Oct; 25(10):1065-70.
  15. Walters TE, Kalman JM. Development of atrial fibrillation after atrial flutter ablation: more a question of when than whether. J Cardiovasc Electrophysiol. 2014 Aug; 25(8):821-823.
  16. Walters TE, Teh AW, Spence S, Kistler PM, Morton JB, Kalman JM. Relationship between the electrocardiographic atrial fibrillation cycle length and left atrial remodeling: a detailed electroanatomic mapping study. Heart Rhythm. 2014 Apr; 11(4):670-6.
  17. McLellan AJ, Ling LH, Ruggiero D, Wong MC, Walters TE, Nisbet A, Shetty AK, Azzopardi S, Taylor AJ, Morton JB, Kalman JM, Kistler PM. Pulmonary vein isolation: the impact of pulmonary venous anatomy on long-term outcome of catheter ablation for paroxysmal atrial fibrillation. Heart Rhythm. 2014 Apr; 11(4):549-56.
  18. Amerena JV, Walters TE, Mirzaee S, Kalman JM. Update on the management of atrial fibrillation. Med J Aust. 2013 Nov 04; 199(9):592-7.
  19. Kumar S, Walters TE, Halloran K, Morton JB, Hepworth G, Wong CX, Kistler PM, Sanders P, Kalman JM. Ten-year trends in the use of catheter ablation for treatment of atrial fibrillation vs. the use of coronary intervention for the treatment of ischaemic heart disease in Australia. Europace. 2013 Dec; 15(12):1702-9.
  20. Walters TE, Kistler PM, Morton JB, Sparks PB, Halloran K, Kalman JM. Impact of collimation on radiation exposure during interventional electrophysiology. Europace. 2012 Nov; 14(11):1670-3.

Publications are derived from MEDLINE/PubMed and provided by UCSF Profiles, a service of the Clinical & Translational Science Institute (CTSI) at UCSF. Researchers can make corrections and additions to their publications by logging on to UCSF Profiles.