With expert guidance, Apple Watch could record multi-lead ECGs and spot ST-segment changes

Although beyond the reach of everyday users, an independent study lends support to the Apple Watch's ECG as an option for cardiologists when standard ECGs are unavailable.
By Dave Muoio
02:08 pm

New data published in JAMA Cardiology suggests that the Apple Watch's ECG tool could not only be used to record multi-lead ECG, but also to spot ST-segment changes among patients with acute coronary syndromes.

The independent study was conducted by researchers from Italy's Magna Graecia University, and enrolled 100 participants who had myocardial infarction or were healthy. And although taking the readings required would be more involved than having the user simply wear the smartwatch as usual, the authors wrote that the approach could be used when a standard ECG is not available to avoid potentially deadly delays in treatment.


The smartwatch's ECG readings were found to be in concordance with those of a standard 12-lead ECG, while the differences in ST deviation between the two approaches were "clinically nonsignificant," the researchers wrote.

Using the standard ECG readings as a reference, the smartwatch's ST-segment elevation demonstrated a sensitivity of 93% and a specificity of 95%. For non-ST-segment elevation, sensitivity was 94% and specificity was 92%.

Of note, six patients were excluded from the analysis due either to conditions that hampered the quality of their smartwatch signal readings, or due to clinical instability. The researchers also stressed the more complicated nature of collecting these types of ECGs with the Apple Watch, and the fact that ECG readings from the device would need to be interpreted by a trained cardiologist.


The researchers enrolled 100 participants between April 2019 and January 2020. Of these, 54 were symptomatic and had an ST-segment elevation myocardial infarction, 27 were symptomatic with a non-ST elevation myocardial infarction and had been admitted to the coronary care unit, and 19 served as healthy controls.

Participants each received a standard 12-lead ECG, and also used the Apple Watch Series 4's ECG app to record and store their readings. Additional leads were collected by taking off the smartwatch and having an attending physician place its sensor on nine different body positions. Leads aVR, aVL and aVF could not be collected using the device.


The Apple Watch Series 4's ECG feature revealed alongside an unprecedented FDA De Novo approval in late 2018. In the time since, Apple has partnered with major names in academia to collect further evidence of its ability to spot potential incidences of atrial fibrillation (and is now turning toward other areas of health monitoring using the wearable device).

In terms of expanding upon the Apple Watch's immediate ECG indications, the Magna Graecia team isn't the first to investigate multi-lead and clinical-setting feasibility.

"Previous studies have explored the possibility for use of the smartwatch to record multiple ECG leads. There are also anecdotal reports of smartwatch use in patients with acute myocardial ischemia," the researchers wrote "However, to our knowledge, there are no studies that prospectively assessed the use of a smartwatch in a series of patients with acute coronary syndromes. Accordingly, the present study aimed to assess the feasibility and agreement of a smartwatch compared with a standard 12-lead ECG in patients with acute coronary syndromes."


"The findings of this feasibility study suggest ST-segment changes on ECG shown with use of a smartwatch agree with those determined with standard ECGs. This agreement may allow the potential for earlier diagnosis of acute coronary syndromes using smartwatch technology," the researchers wrote.


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