Mayo breakthrough in single-lead ECG tracings from an Apple Watch

May 4, 2022 0 By CH Unnikrishnan

Single-lead ECG tracings from an Apple Watch interpreted by an artificial intelligence (AI) algorithm developed at Mayo Clinic effectively identified patients with a weak heart pump. A new study presented by Mayo researchers   at the Heart Rhythm Society conference,  demonstrated the possibility for a scalable tool to be developed to screen and monitor heart patients for this condition wherever they are.

In this decentralised, prospective study, the patients were enrolled by email then they downloaded an app that securely transferred watch ECGs in the background. Study participation was high, demonstrating the possibility for a scalable tool to be developed to screen and monitor heart patients for this condition wherever they are, said the Mayo team in the presentation. 

According to Dr Paul Friedman, chair of the Department of Cardiovascular Medicine at Mayo Clinic in Rochester, left ventricular dysfunction — a weak heart pump — afflicts 2 percent to 3 percent of people globally and up to 9 percent of people over age 60. 

“It may have no symptoms, or be associated with shortness of breath, leg swelling or racing heart beats. What is important is that once we know a weak heart pump is present, there are many lifesaving and symptom-preventing treatments available. It is absolutely remarkable that AI transforms a consumer watch ECG signal into a detector of this condition, which would normally require an expensive, sophisticated imaging test, such as an echocardiogram, CT scan or MRI,” Dr Friedman says. 

The single lead ECG tracing gains significance as a standard ECG uses 12 electrode leads strategically placed on a person’s chest, arms and legs to create a tracing used to evaluate the heart’s electrical signals. A previous Mayo research showed that the 12-lead ECG and AI algorithm can identify a weak heart pump. However, this information is useful to clinicians in an office setting. It may be recalled that the 12-lead ECG algorithm was awarded breakthrough device designation by the Food and Drug Administration in 2019 and emergency use authorization for COVID-19 in 2020.

In order to interpret ECG signals generated from the single lead on an Apple Watch, Mayo researchers modified the already established 12-lead algorithm for low ventricular ejection fraction (weak heart pump). This is now being licensed to Anumana Inc., an AI-driven health technology company. 

To adapt the 12-lead algorithm to work with a single lead watch signal, Dr Itzhak Zachi Attia, the lead AI scientist in the Department of Cardiovascular Medicine at Mayo Clinic, created an adaptation technique that translated the single-lead readings into signals understandable by the algorithm. Dr. Attia is co-director of Artificial Intelligence in the Department of Cardiovascular Medicine.

Participants securely transmitted 125,610 ECGs from 46 states and 11 countries over the six-month study period. The average app use was about two times a month. Overall participation was high, as 92% used the app more than once. Each patient recorded many ECGs, and researchers chose the cleanest readings.

“Approximately 420 patients had a watch ECG recorded within 30 days of a clinically ordered echocardiogram, or ultrasound of the heart, a standard test to measure pump strength. We took advantage of those data to see whether we could identify a weak heart pump with AI analysis of the watch ECG. While our data are early, the test had an area under the curve of 0.88, meaning it is as good as or slightly better than a medical treadmill test. AI analysis of the watch ECG is a powerful test to identify a weak heart pump,” said Dr. Attia in a recent statement issued by Mayo. 

The researchers worked with Mayo Clinic’s Center for Digital Health to develop the smartphone app that study participants used to send single lead ECGs from their Apple Watch. A total of 2,454 Mayo Clinic patients with an iPhone, the Mayo Clinic App and a series 4 or later Apple Watch took part in the study. The app securely sent all previous watch ECGs and additional ones as they were recorded by patients to a Mayo secure data platform, where they were analysed.

“This Apple Watch ECG study demonstrates that, from a patient’s wrist whether they live in Brazil or Baton Rouge, an app-based access to a medical center can help address health disparities by making high-level diagnostics accessible to more people in real time,” says Dr Bradley Leibovich, medical director of Mayo Clinic’s Center for Digital Health.

“This test is the first step, as it demonstrates we can get medically useful information from a single-lead watch. Our next steps include global prospective studies to test this prospectively in more diverse populations and demonstrate medical benefit. This is what the transformation of medicine looks like: inexpensively diagnosing serious disease from your sofa,” said Dr. Friedman, in the Mayo statement. 

Mayo Clinic clarified that this study was fully funded by itself and there was no technical or financial support from Apple. Drs. Attia and Friedman, along with others, are co-inventors of the low ejection fraction algorithm licensed to Anumana and may benefit from its commercialization.