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Department Cardiovascular Medicine
Primary Location Cleveland Clinic Main Campus
Type of Doctor Adults Only
Languages English
Surgeon No
Cleveland Clinic Main Campus
Primary Location

Cleveland Clinic Main Campus


Additional Locations

Specialties & Treatments

Treatment & Services

  • Advanced Ischemic Heart Disease Center
  • Atrial Fibrillation Center
  • Biventricular Pacemaker
  • Cardiac Electrophysiology
  • Cardiac Electrophysiology and Pacing Section
  • Cardiovascular Medicine
  • Cardiovascular Medicine Department
  • Cardioversion
  • Catheter Ablation
  • Clinical Trials
  • Implantable Cardioverter Defibrillator (ICD)
  • Implantable Cardioverter Defibrillator (ICD) Lead Extraction
  • Lifevest
  • Pacemaker Implant
  • Pacemaker Lead Extraction
  • Pulmonary Vein Ablation Procedure
View all 16 Treatment & Services +

Specialty in Diseases & Conditions

  • Abnormal Heart Beats - Women
  • Abnormal Heart Rhythms
  • Arrhythmogenic Right Ventricular Dysplasia
  • Atrial Fibrillation
  • Atrial Flutter
  • Bradyarrhythmias
  • Cardiac Implantable Electronic Device Infection
  • Heart Palpitations
  • Long QT Syndrome (LQTS)
  • Sudden Cardiac Death (Sudden Cardiac Arrest)
  • Supraventricular Tachycardia
  • Syncope
  • Ventricular Fibrillation
  • Ventricular Tachycardia
  • Wolff-Parkinson-White Syndrome (WPW)
View all 15 Specialties +


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About Thomas Callahan, MD

Thomas Callahan, IV, MD, is Staff Physician and Director of Inpatient Services in the Section of Pacing and Electrophysiology of the Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute at Cleveland Clinic. He is also the Associate Program Director for Cleveland Clinic’s cardiology and electrophysiology fellowships.

In addition to office visits, Dr. Callahan also offers scheduled follow up virtual visits to select patients, through the Cleveland Clinic Express Care ® Online app. This platform allows patients to see their physician live, using their smartphone, tablet or computer.

Specialty interests: Abnormal heart rhythm, atrial fibrillation, sudden cardiac death, supraventricular tachycardia, ventricular tachycardia, PVCs, Wolff-Parkinson-White syndrome, biventricular pacemaker, catheter ablation, implantable cardiac defibrillator, lead extraction

Number of Procedures Performed: Dr. Callahan has performed more than 900 catheter ablation procedures throughout his career.

Success rates: Cleveland Clinic is nationally and internationally renowned for the world’s best cardiovascular care. Success rates for specific procedures are available at http://my.clevelandclinic.org/heart/about-heart-vascular-institute/treatment-outcomes.aspx

Education and Training: Dr. Callahan received his undergraduate degree from Oberlin College, OH. He received his master's degree from the University of Michigan, and he earned his medical degree from Eastern Virginia Medical School, Norfolk. He joined Cleveland Clinic in 2003 and completed fellowships in Cardiovascular Medicine Cardiac Electrophysiology and Pacing. Prior to coming to Cleveland Clinic, he was a resident at the Hospital of the University of Pennsylvania, where he was Chief Resident in internal medicine.

Publications and Speaking:  Dr. Callahan has authored and co-authored many articles published in leading medical journals.

About Dr. Callahan: “I enjoy my field because we have the ability to make many patients feel dramatically better. I am also excited by the constant advancement in the field.”

Leisure Activities: Dr. Callahan is a private pilot. He also enjoys skiing and spending time with his family.

Education & Professional Highlights

Education & Professional Highlights


Education & Fellowships

Fellowship - Cleveland Clinic
Cardiovascular Medicine
Cleveland, OH USA

Residency - Hospital of the University of Pennsylvania
Internal Medicine
Philadelphia, PA USA

Internship - Hospital of The University of Pennsylvania
Internal Medicine
Philadelphia, PA USA

Medical Education - Eastern Virginia Medical School
Norfolk, VA USA

Graduate School - University of Michigan
Ann Arbor, MI USA

Undergraduate - Oberlin College
Oberlin, OH USA


  • Internal Medicine - Clinical Cardiac Electrophysiology
  • Internal Medicine - Cardiovascular Disease

Specialty Interests

Abnormal heart rhythm, atrial fibrillation, sudden cardiac death, supraventricular tachycardia, ventricular tachycardia, PVCs, Wolff-Parkinson-White syndrome, biventricular pacemaker, catheter ablation, implantable cardiac defibrillator, lead extraction

Awards & Honors

  • 2006, Dawson Award for Clinical Excellence and Humanism
  • 2004, Frederic J. Pashkow Award for Clinical Excellence
Research & Publications

Research & Publications

See publications for Thomas Callahan, MD.

(Disclaimer: This search is powered by PubMed, a service of the U.S. National Library of Medicine. PubMed is a third-party website with no affiliation with Cleveland Clinic.)

Industry Relationships

Industry Relationships

Cleveland Clinic physicians and scientists may collaborate with the pharmaceutical or medical device industries to help develop medical breakthroughs or provide medical expertise or education. Cleveland Clinic strives to make scientific advances that will benefit patient care and support outside relationships that promise public benefit. In order for the discoveries of Cleveland Clinic physicians' and scientists' laboratories and investigations to benefit the public, these discoveries must be commercialized in partnership with industry. As experts in their fields, Cleveland Clinic physicians and scientists are often sought after by industry to consult, provide expertise and education.

To assure professional and commercial integrity in such matters, Cleveland Clinic maintains a program that reviews these collaborations and, when appropriate, puts measures in place to minimize bias that may result from ties to industry. Cleveland Clinic publicly discloses the names of companies when (i) its physicians/scientists receive $5,000 or more per year (or, in rare cases, equity or stock options) for speaking and consulting, (ii) its physicians/scientists serve as a fiduciary, (iii) its physicians/scientists receive or have the right to receive royalties or (iv) its physicians/ scientists hold any equity interest for the physician's/scientist's role as inventor, discoverer, developer, founder or consultant.* In publicly disclosing this information, Cleveland Clinic tries to provide information as accurately as possible about its physicians' and scientists' connections with industry.

As of 7/3/2023, Dr. Callahan has reported the financial relationships with the companies listed below. In general, patients should feel free to contact their doctor about any of the relationships and how the relationships are overseen by Cleveland Clinic. To learn more about Cleveland Clinic's policies on collaborations with industry and innovation management, go to our Integrity in Innovation page.

Consulting and/or Speaking. Dr. Callahan receives fees of $5,000 or more per year (or, in rare cases, equity or stock options) as a paid consultant, speaker or as a member of an advisory committee for the following companies:

  • Philips

Public Health Service-Reportable Financial Conflicts of Interest. Cleveland Clinic scientists and physicians engage in basic, translational and clinical research activities, working to solve health problems, enhance patient care and improve quality of life for patients. Interactions with industry are essential to bringing the researchers' discoveries to the public, but can present the potential for conflicts of interest related to their research activities. Click here to view a listing of instances where Cleveland Clinic has identified a Public Health Service (PHS)-Reportable Financial Conflict of Interest and has put measures in place to ensure that, to the extent possible, the design, conduct and reporting of the research is free from bias.

* Cleveland Clinic physicians and scientists subscribe to the guidance presented in the PhRMA Code on Interactions with Healthcare Professionals and the AdvaMed Code of Ethics on Interactions with Health Care Professionals. As such, gifts of substantial value are generally prohibited.

Patient Satisfaction Reviews

289 Patient Satisfaction Reviews

The Patient Satisfaction Rating is an average of all responses to the care provider related questions shown below from our nationally-recognized Press Ganey Patient Satisfaction Survey. Patients that are treated in outpatient or hospital environments may receive different surveys, and the volume of responses will vary by question.

Responses are measured on a scale of 1 to 5 with 5 being the best score.

The comments are submitted by patients and reflect their views and opinions. The comments are not endorsed by and do not necessarily reflect the views of Cleveland Clinic.

Overall Star Ratings
4.9 out of 5
Explains 4.9
Listens 4.9
Courtesy, Respect & Concern 4.9
Patient Rating of Doctor 4.9

66 Patient Comments

Reviewed on Jan 23, 2024

I work with Dr Callahan in conjunction with my doctors in Chicago. Dr Callahan provides a confident medical opinion that I respect and trust.

Reviewed on Jan 8, 2024

Drs Callahan and Abbasi spent a good deal of time reviewing my case and provided excellent information in explaining treatment options, benefits and risk. That is greatly appreciated. Many times we encounter doctors that rush in and out and don't spend enough time going over everything with the patient. They were great! I will be having my procedure performed by Dr Callahan at the Cleveland Clinic.

Reviewed on Dec 18, 2023

Dr.Callahan patiently explains important information and answers every question we have. He is very professional and compassionate. I am so fortunate to have him as my Dr.

Reviewed on Dec 18, 2023

Dr Callahan is always respectful and caring and explains everything very clearly.

Reviewed on Dec 13, 2023

"Ease of getting the care you needed" was fine. I am aware that nearly all doctors and their staff are overloaded. I am concerned about getting timely care since I have numerous medical conditions. It's easy to schedule an appointment, it's not easy to get an appointment that's not 5 months away, and in some cases, my doctors' calendar's aren't even open for the next 6 months.

Reviewed on Dec 12, 2023

Dr. Callahan is an exemplary physician and a credit to the Cleveland Clinic

Reviewed on Nov 28, 2023

Dr Callahan becomes your personal trusted Doctor, and you know you are in the Best of Care.

Reviewed on Nov 20, 2023

Dr. Callahan is so popular that getting an appointment with him is like getting tickets to a Taylor Swift concert. But like the concert, getting an appointment is worth it.

Reviewed on Nov 20, 2023

Dr. Callahan explained future options clearly. I was very satisfied with my appointment.

Reviewed on Nov 20, 2023

I have great confidence with the Dr and his staff.

Reviewed on Nov 20, 2023

I have no complaints about Dr. Callaghan. I think the world of him, and the staff.

Reviewed on Nov 20, 2023

I've had my heart in Dr. Callahan's hands four times in a decade. He' s warm, humble and an excellent doctor.

Reviewed on Nov 15, 2023

We were consulting Dr. Callahan (whom we saw previously) regarding recommendations of a non- Cleveland Clinic doctor. Dr. Callahan was kind, listened intently to our questions, explained his opinion and recommendations in detail, and allowed for additional questions. We implicitly trust Dr. Callahan's clinical judgment and technical skill and felt relieved having his opinion. We feel truly blessed to have him.

Reviewed on Nov 15, 2023

We felt very comfortable with the video visit once we got through the initial loss of connection. Dr. Callahan was relaxed and engaging and helped us to feel comfortable.

Reviewed on Nov 14, 2023

Very good is not an adequate description for Dr. Callahan. He is excellent, superior, unusual. I was so impressed, as usual. Although I had several tests prior to this visit, he did not start with the test results. He started with ME! He asked me how I was, to tell him all about how I am, while asking me questions to further probe my responses. Only after that did he respond to my test results in light of my own experiences. Whenever he recommends something, he always describes the pros and cons, along with side effects, always allowing the final decision up to me. Besides all this he has such a relaxed presence that makes me feel as though I'm the only concern he has...he's amazing!!!

Reviewed on Nov 10, 2023

Dr. Shady Nakhla and Dr. Justin Lee were great, provided exceptional service.

Reviewed on Oct 25, 2023

Dr Callahan and his staff have been first rate. I would highly recommend him to anyone looking for help.

Reviewed on Oct 23, 2023

The only thing I can say is that once we were put in the doctors room, we waited a hour for him to come in, I thought that was much to long to wait

Reviewed on Oct 16, 2023

Dr. Callahan is very easy to talk to and has the ability to put my mind at ease, and to explain my situation at a level that I can comprehend.

Reviewed on Oct 16, 2023

Excellent provider extremely thorough competent and empatheticSome difficulty getting hold of MA and scheduling appointmentSuperior physician recommend without reservationI am a physician and he is exemplary of what our profession should be

Reviewed on Oct 11, 2023

Dr. Callahan was extremely thorough in his evaluation and options offered for my concerns with AFIB.

Reviewed on Oct 9, 2023

This was my first experience at the Cleveland clinic. Dr Callahan was a second opinion for me and I left his office feeling very reassured and certain about my decision to treat my AFib. He was very calming and assuring about my consult. I left feeling light a great weight had been lifted off my shoulders. Thank you

Reviewed on Oct 4, 2023

I particularly appreciate the doctor listened to my questions and concerns. I felt that the advice I received from my doctor was based not only on his knowledge and experience but on the concerns I expressed, as well,

Reviewed on Sep 20, 2023

Trust Dr. Callahan very much.

Reviewed on Sep 19, 2023

Dr. Callahan treated me very well, as always and left me feeling confident about my care.

Reviewed on Sep 19, 2023

Thorough, courteous, thoughtful and caring Doctor.

Reviewed on Sep 19, 2023

Outstanding Staff from beginning to end. Very highly recommended and accomplished physician. Very professional yet personable. An excellent experience so far.

Reviewed on Aug 28, 2023

I was well satisfied that I was scheduled for an appointment with Dr. Callahan sooner than I expected.

Reviewed on Aug 28, 2023

Dr. Callahan has always been solicitous of my concerns and has explained concisely and clearly all the factors about my condition.

Reviewed on Aug 21, 2023

I had a very positive experience with Dr. Callahan. Clinic staff were all very helpful.

Reviewed on Aug 14, 2023

Dr. Callahan was exceptional in his concern, his explanation of options, and his responses to the many questions.

Reviewed on Aug 14, 2023

Dr Callahan is magnificent. Outstanding in every way

Reviewed on Aug 14, 2023

Dr Callahan was brilliant, kind, caring and took time to explain everything. I like that he stated that at any time I had questions or concerns to reach out to him. I miss Dr Tchou but I really like Dr Callahan's manner, knowledge and concern

Reviewed on Aug 9, 2023

Dr. Callahan was great.

Reviewed on Aug 8, 2023

Dr. Callahan is professional, listened to and answered all my questions thoroughly.

Reviewed on Aug 2, 2023

So glad that I got to see Dr. Callahan. He is not only a great surgeon, but a great man.

Reviewed on Aug 2, 2023

This was my very first meeting with Dr. Callahan. I have been in long term AFib, and I wanted to discuss treatment options with him. He went through each of my options, and completely explained why each WAS NOT my best course of action at this time. His degree of knowledge is very impressive, and he inspired a lot of confidence in me. It was a great first visit!

Reviewed on Jul 31, 2023

Dr Callahan is the best: kind, concerned, smart, and always takes as much time as you need!!

Reviewed on Jul 31, 2023

Dr. Callahan and his staff have taken care of me for a long time. He is very kind, and very talented. Much appreciated.

Reviewed on Jul 17, 2023

As with all good physicians, at every facility, you must take what's offered. Availability is not plentiful.

Reviewed on Jul 10, 2023

I am very pleased to be invited into the medical care of Dr. Callahan. I look forward to receiving his care and guidance.

Reviewed on Jul 10, 2023

Like all situations like this, the doctor only has a short amount of time to address each patient. I wish they were allocated enough time to really focus on my case for 15-20 minutes. Again, this is normal procedure, it would just be great to be the 'only patient' for long enough for the doctor to truly review the file. I really liked Dr. Callahan. He's clearly a true professional.

Reviewed on Jul 10, 2023

Dr. Callahan was patient, professional and more than willing to answer our questions and concerns.

Reviewed on Jul 10, 2023

I found Dr. Callahan to be a professional, knowledgeable, helpful, attentive, and patient EP.

Reviewed on Jul 10, 2023

Dr Callahan is fantastic and has my complete confidence

Reviewed on Jul 10, 2023

Great Experience. I felt that Dr. Callahan listened and heard my concerns. We had a clear plan of action leaving his office.

Reviewed on Jun 27, 2023

Dr Callahan very good doctor

Reviewed on Jun 26, 2023

Dr. Callahan is awesome!

Reviewed on Jun 26, 2023

Provider was amazing with great bedside manner

Reviewed on Jun 17, 2023

*Dr. Wazni is the best doctor I've ever had. Beyond compare -

Reviewed on May 30, 2023

Dr. Extremely knowledgeable & sensitive to all health concerns!-one of the very best doctors I've ever had!!!!

Reviewed on May 30, 2023

In past yr have had & presentlyhave 3rd electrophysiologist (Dr Callahan- the very BEST!

Reviewed on May 30, 2023

From the J2-2 receptionist all the way to Dr. Callahan himself, I was treated with the utmost respect and care. Cleveland Clinic has the "cream of the crop"!

Reviewed on May 30, 2023

Dr. Callahan and his assistant were both excellent and very helpful with my symptoms. I was very Impressed with the Cleveland Clinic downtown and the care and kindness practiced by everyone, from the valets to the physicians and staff.

Reviewed on May 24, 2023

Dr. Callahan is an excellent Doctor who has my best interests covered.... Thank you

Reviewed on May 12, 2023

Dr. Callahan is PHENOMENAL!!!!!

Reviewed on May 12, 2023

The dr gave us a lot of excellent information and I am feeling better. Dr Callahan is not just a 5, he is a 10!

Reviewed on Apr 28, 2023

I am very impressed with the support staff at your facilities. I was also impressed and thankful for the knowledge, consideration, patience and understanding of Dr. Callahan. Look forward to more interactions.

Reviewed on Apr 18, 2023

Dr Callahan is a great doctor but some of that staff on that day were not very caring.

Reviewed on Apr 14, 2023

Dr Thomas Callahan, & staff are AWESOME! They take time to explain everything. They are caring and ask questions to make sure you understand everything!

Reviewed on Mar 31, 2023

Dr. Callahan came highly recommended to me and I was not disappointed. He made a plan to do all my testing and explained all possible outcomes based on those tests. I felt comfortable and confident with him and his team.

Reviewed on Mar 31, 2023

Dr. Callahan's knowledge and understanding of medical issues outside his EP specialty increased my confidence in him tremendously. So many specialists on main campus focus inflexibly within their discipline. Patients are more complicated than that. Dr. Callahan seems to understand that better than many of his colleagues.

Reviewed on Mar 31, 2023

Visit with the Dr. Callahan was fine. He explained to me what I was concerned about and answered my questions. Again, I did not feel rushed after the long wait.

Reviewed on Mar 31, 2023

Physician assistant was easy to deal with. He made us feel relaxed and he answered all of our questions. Very courteous.

Reviewed on Mar 15, 2023

At the time I felt he was just telling me that I was going to need another ablation and dismissing the success of the medications which made me very sad and discouraged. I now realize he is probably correct, but at the time a short Zoom with that kind of news left me rather stunned and discouraged.

Reviewed on Mar 7, 2023

Dr Callahan is a good and respectful listener.

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