September 18, 2018
6 min read

Cardiologists react to new Apple Watch ECG capabilities

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

Jagmeet Singh
Jagmeet P. Singh

Upon Apple’s announcement on Sept. 12 that the redesigned Apple Watch Series 4 will feature an electrical heart rate sensor that can take an electrocardiogram using a new ECG app, Cardiology Today spoke with cardiologists about the impact of this new technology and how it may be used in clinical practice.

The new Apple Watch enables wearers to take an ECG reading right from the wrist via electrodes and the electrical heart rate sensor build into the watch. With the app, users can receive a heart rhythm classification within 30 seconds, notifying users whether the heart is beating in a normal pattern or whether there are signs of atrial fibrillation, according to a press release issued by Apple. All related recordings, classifications and notes are stored in PDF format within the Health app for physicians to review upon request. This technology can also alert the user if the heart rate exceeds or falls below a specific threshold.

‘A game changer’

The FDA cleared the new ECG app as a class II medical device, through a de novo classification. In a letter to Apple, the FDA noted that the ECG app is “intended for use with the Apple Watch to create, store, transfer and display a single-channel ECG similar to a Lead I ECG. The ECG app determines the presence of atrial fibrillation or sinus rhythm on a classifiable waveform. The ECG app is not recommended for users with other known arrhythmias.”

The FDA also noted that the data generated by the ECG app is for “informational use only” and “the user is not intended to interpret or take clinical action based on the device output without consultation of a qualified healthcare professional.”

The ECG app is intended for those aged 22 years and older.
“This is a game changer,” Cardiology Today Editorial Board Member Jagmeet P. Singh, MD, DPhil, associate chief of the cardiology division at Massachusetts General Hospital, said in an interview. “Since the sensor and its ability to record ECGs and classify the heart rhythm is FDA-approved, it will begin to find its way into clinical practice and potentially into the electronic health record. It will certainly create a heightened awareness about rhythm disturbances and atrial fibrillation.”

Broadened monitoring capabilities

The ability to detect abnormal heart rhythms, especially out of the office, can have important implications, experts told Cardiology Today.

“This is potentially important because some of the arrhythmias that [this technology] may be able to identify, such as atrial fibrillation, can have devastating consequences, such as stroke, if not identified and addressed with medical therapy,” Nicholas Leeper, MD, cardiologist and associate professor of vascular surgery and cardiovascular medicine at Stanford University Medical Center, said in an interview.

Nicholas Leeper 2018
Nicholas Leeper

The updated capabilities of the Apple Watch Series 4 may broaden the monitoring capabilities of existing technologies.

This new technology “is less invasive than a Holter monitor, has great battery life and can be with the person 24/7,” John P. Higgins, MD, MBA, professor of cardiovascular medicine at the University of Texas Health Science Center McGovern Medical School in Houston, told Cardiology Today.

Technologies such as the Apple Watch, which allow continuous or periodic monitoring, can help clinicians identify intermittent arrhythmias that are difficult to capture on the short-term monitors that are typically used, experts said. In addition, the Apple Watch Series 4 can provide clinicians with real-time heart rate and summaries, which can aid in providing exercise and medication prescriptions while motivating patients to adhere to their regimens.

“[This can be] a handy teaching tool, as well as helping people use biofeedback to relax and lower their heart rate with training,” Higgins said.

John P. Higgins

Cardiologists should approach patients who have the Apple Watch Series 4 in a positive and collaborative manner.

“It shows motivation,” Seth S. Martin, MD, MHS, FACC, FAHA, FASPC, assistant professor of medicine, cardiologist at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease and Cardiology Today Editorial Board Member, said in an interview. "I will start off on a positive note and ask them to share their findings to review together. The patient is there in clinic for us to help guide them. They're in the driver's seat of their care and they’re going to decide what they want to monitor and what treatments are right for them. We’re there to guide them in interpretation of the data, and collaborate in deciding what other tests would be helpful and what actions from a treatment standpoint need and don't need to be taken."

More data

This technology will help increase awareness of heart health among users and can also aid physicians in generating more data on their patients. However, this technology may also have some drawbacks, such as false positives, experts told Cardiology Today.

Seth S. Martin
Seth S. Martin

“Other arrhythmias are merely a nuisance and don’t require any treatment at all,” Leeper told Cardiology Today. “I am concerned that many otherwise healthy people who — if monitored continuously 24 hours a day — will be found to have brief spells of arrhythmias that have an unknown natural history. Such nebulous diagnoses might not only induce anxiety, they could cause patients to be exposed to additional tests and therapies that have their own set of complications.”

In a column published in The New York Times, Aaron E. Carroll, MD, MS, professor of pediatrics at Indiana University School of Medicine, wrote that although the device allows doctors to monitor their patients outside of the office and diagnose unknown heart problems, it may also reflect wider problems such as false positives and false negatives, especially from its irregular rhythm notification feature.

“The reality is that we don't know the net effect yet,” Martin told Cardiology Today. “It is a valid concern that if a good diagnostic test is applied in a population with low pre-test probability, then there will be a lot of false positives. The most extreme example would be young persons with a near zero pre-test probability; in this setting, nearly all positives will be false positives. This is actually a great opportunity to increase awareness of Bayesian inference.”

Even with the presence of false positives and negatives, some experts think that the benefits outweigh the risks of this new feature.

“While there will always be false positives and false negatives with any testing device we use, and I don't recommend widespread screening of asymptomatic healthy adults, the advantages appear to outweigh the disadvantages for select groups of individuals, eg, those with a history of/current atrial fibrillation, atrial flutter, those with palpitations or family history of arrhythmias or those with stroke/TIA associated with possible occult atrial arrhythmias whose detection is important in their management,” Higgins told Cardiology Today. “In a world where the average person sees their health care provider only 2 days per year, I welcome technology that can help providers monitor them the other 363 days of the year.”

As more patients wear devices such as the Apple Watch, clinicians need to learn how to best utilize the additional data when treating their patients, experts said.

“There will almost certainly be a learning curve when we learn how to deal with patients who have a small burden of low-risk, asymptomatic arrhythmias,” Leeper said.

More research is also needed before this capability can be integrated into clinical practice.

Khaldoun Tarakji
Khaldoun Tarakji

“Excessive amount of data could become noise if it does not lead to action,” Khaldoun Tarakji, MD, MPH, cardiologist at Cleveland Clinic and Cardiology Today Next Gen Innovator, said in an interview. “Exchanging health care data needs to have the right platform in order to make it feasible for physicians to use it. A wearable device should not mean a wearable physician. These products should facilitate health care and make it more efficient and not increase the burden on physicians.”

‘The era of wearables’

Cardiology Today asked cardiologists how they might use the data generated from technologies like the new Apple Watch, as more individuals and clinicians begin to accept new technologies as a way to help care for their patients.

Higgins said he is open to using the data generated from the Apple Watch Series 4. “It has been shown to accurately diagnose some arrhythmias such as atrial fibrillation, which is the commonest cause of stroke. I would welcome additional data on my patients’ rhythms, especially if they have symptoms, and they cannot readily get an ECG.”

Devices such as the Apple Watch are becoming more readily available, which may have the potential to change how clinicians practice.

“The era of wearables has now truly dawned upon us,” Singh said. “The onus is now on us to begin to transition the culture of care from one that is ‘periodic and transactional’ to one that could be continuous.” – by Darlene Dobkowski


Carroll AE. "That New Apple Watch EKG Feature? There Are More Downs Than Ups." The New York Times, Oct. 8, 2018.

For more information:

John P. Higgins, MD, MBA, can be reached at 6431 Fannin St., MSB 4.262, Houston, TX 77030; email:

Nicholas Leeper, MD, can be reached at 300 Pasteur Drive, 3rd Floor, A32, Palo Alto, CA 94304.

Seth S. Martin, MD, MHS, FACC, FAHA, FASPC, can be reached at Johns Hopkins School of Medicine, Division of Cardiology, 600 N. Wolfe St., Carnegie 591, Baltimore, MD 21287; email:; Twitter: @SethShayMartin.

Jagmeet P. Singh, MD, DPhil, can be reached at Cardiac Unit Associates, 55 Fruit St., Boston, MA 02114; email:; Twitter: @JagSinghMD.

Khaldoun Tarakji, MD, MPH, can be reached at Cleveland Clinic Main Campus, Mail Code J2-2, 9500 Euclid Ave., Cleveland, OH 44195; Twitter: @khaldountarakji.

Disclosures: Higgins, Leeper and Singh report no relevant financial disclosures. Martin reports he received Apple Watches from Apple for clinical research. Tarakji reports he serves on a medical advisory board for AliveCor and Medtronic.