Apple Watch Series 4, 5, 6 and 7

The Apple Watch Series 4, 5, 6 and 7 all have an ECG app. The first model arrived in the fall of 2018 and the most recent Series 6 landed in 2021. The ECG app works in most countries, takes around 30 seconds to complete, and sends the data it collects to the Health app of the user's iPhone. From there it can be sent to a doctor if required.

An ECG is taken by completing an electrical circuit across the wearer's body. In the case of the Apple Watch, this means the heart rate monitor sitting on your wrist as normal, then you touch the Digital Crown with the index finger of your opposite hand to complete the circuit. The watch then tells you if your heart rate is normal or shows signs of Afib.

The lower-priced Apple Watch SE has a heart rate monitor but cannot take an ECG.

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Samsung Galaxy Watch 3 and Watch Active 2

Two current Samsung smartwatches now offer ECG functionality, having been approved in the US, Europe and Samsung's native South Korea. These are the Galaxy Watch 3 and the slimmer Watch Active 2. Both of these watches perform an ECG using the heart rate monitor and when the wearer places a finger of their opposite hand on the case.

As with other ECG wearables, you need to place your forearm on a flat surface and relax as best you can, without moving, while the 30-second ECG takes place.

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Withings ScanWatch and Move ECG

French technology firm Withings offers a pair of smartwatches with ECG functionalist, called the Move ECG and the ScanWatch. The former is cheaper and a little older, while the latter is the company's latest and greatest. They both track exercise, heart rate and sleep, while the ScanWatch also has a simple display for delivering notifications and extra information.

Unfortunately, while clinically validated and available to buy in Europe, Withings is till waiting for approval from the FDA. Until that happens, it cannot sell its ECG devices in the United States. The company had hoped to overcome this hurdle before the end of 2020, but as of February 2021 this still hasn't happened.

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Fitbit Sense

Google-owned Fitbit is best known for its fitness trackers, but also now sells a smartwatch in the form of the Sense. This is a fully-fledged wearable with all of the health and fitness features you would expect from an Apple Watch, plus notifications, water resistance, the ability to handle calls, stream music, make contactless payments and more.

It also has a heart rate monitor and can take an ECG. As with others, you just have to be wearing the Sense and place your finger on the aluminum case to complete the ECG reading. Like the Apple Watch, the Fitbit Sense also keeps an eye on abnormally high and low heart rates. As with other wearables, the ECG app of the Fitbit Sense isn't available everywhere, but as of February 2021 it works in The US, UK and Europe, with Canada, New Zealand and Singapore coming soon. Fitbit says the ECG app should not be used by anyone under the age of 22.

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AliveCor KardiaMobile 6L

Now for something a little different. The AliveCore KardiaMobile 6L is not a smartwatch or a wearable off any kind, but instead it is a portable, pocket-sized ECG device. Where the smartwatches listed above perform the equivalent of a single-lead ECG, the KardiaMobile 6L, as its name suggests, takes a six-lead ECG.

The device has two electrodes on the top for your index fingers and a third underneath to rest on the skin of your left leg. That way, it can perform and more detailed, multi-lead ECG, while also requiring no use of gels and wires. The ECG reading is sent over Bluetooth to a smartphone app. AliveCore also sells a single-lead version, simply called the KardiaMobile.

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