Heart rate monitors are part and parcel of smartwatches and fitness trackers nowadays, but an electrocardiogram (ECG/EKG) has quickly become a staple feature of health wearables.
The technology is designed to help people keep closer tabs on their heart health and is used to help identify atrial fibrillation (Afib) a serious medical condition that is a leading cause of stroke.
ECG was thrust into the wearable spotlight via the Apple Watch Series 4 way back in 2018, but it can now be found on smartwatches from Samsung, Google, Fitbit, and even Huawei and Garmin.
What is ECG and why is it a useful feature to have on a smartwatch? We get into all of the key details below.
What is ECG?
Most wearables have optical heart rate monitors, which use flashing LEDs to penetrate the skin and detect blood flow. When light is reflected off the flow of blood, it’s captured by the sensors.
The algorithm then gets to work to turn that into an estimation of your heart rate.
But it’s not as accurate as it could be – especially where medical issues are involved.
Enter the electrocardiogram (ECG or EKG). Rather than measuring blood flow, it’s designed to measure how well your heart is working.
It’s a term you’d more commonly hear in the medical industry, referring to an electrocardiograph that's used to detect cardiac abnormalities.
Why would I buy an ECG smartwatch?
An ECG smartwatch can detect if you have atrial fibrillation, a condition that causes an irregular heart rate and is a leading cause of strokes.
Taking an ECG reading on your watch can tell you if you have a healthy heart rhythm – but for many people, the feature is something you'll likely use once and then forget about.
But for a large subset of people, having ECG capabilities can be hugely beneficial.
Smartwatches from the likes of Apple and Fitbit can export an ECG graph of your heart rate, which can be a huge help when talking to your doctor.
“ECG on wearables is super high value for a small segment. It is probably going to be more advantageous to our users over 50 than 20-year-olds, but we're trying to build something for everybody," Dr. Conor Heneghan, Director of Research Algorithms at Fitbit told Wareable.
"Afib can come and go, as can conditions that affect the rhythm of your heart. That means having a device that can take spot readings at any time, makes it a hugely powerful health tool to have at your disposal," he said.
How do ECG smartwatches work?
Most watches have a built-in ECG sensor, that can take a spot reading of your heart rate rhythm.
You start the app and then place your finger on a specific part of the watch (usually the case or crown) for the duration of the test.
Fitbit has recently launched a new feature that continuously monitors heart rate rhythms, and can look for atrial fibrillation using the PPG sensor.
While this has an advantage over ECG watches for spotting Afib, ECG smartwatches offer the benefit of being able to export a graph of your heart rate rhythm.
Which smartwatches have ECG?
The list of smartwatches that currently include an ECG is the following:
- Apple Watch Series 9 (and 4-8)
- Apple Watch Ultra 1/2
- Huawei Watch 4
- Huawei Watch Ultimate
- Huawei Watch D
- Huawei Watch GT 3 Pro
- Samsung Galaxy Watch 6
- Samsung Galaxy Watch 6 Classic
- Samsung Galaxy Watch 5
- Samsung Galaxy Watch 4
- Samsung Galaxy Watch Active 2
- Samsung Galaxy Watch 3
- Google Pixel Watch 2
- Google Pixel Watch
- Fitbit Sense
- Fitbit Sense 2
- Fitbit Charge 6 (and Charge 5)
- Garmin Venu 3 (and Venu 2 Plus)
- Garmin Fenix 7 Pro
- Garmin Epix Pro
- Withings ScanWatch
- Withings Move ECG
- Coros Vertix 2
- Coros Apex 2/Apex 2 Pro
- Amazfit Smartwatch 2
ECG wearables available today
Apple Watch Series 4 - Series 9
The latest Apple Watch Series 9 (and the Series 4, 5, 6, 7, and 8) has ECG functionality, with sensors built into the ceramic heart rate monitor under the watch, and also the Digital Crown.
Fire up the ECG app, pop your finger on the crown and you'll be guided through the reading.
You'll get a notification of whether the reading was normal or Afib and an EKG graph of your heart rate will be logged in the Apple Health smartwatch app, which can be downloaded and shared with your doctor.
Apple has FDA approval for its ECG, as well as clearance in the European Economic Area with more than 20 countries now able to make use of the health feature.
Fitbit Sense 2
The Fitbit Sense 2 is the company's first health watch, and it brings a host of new sensors including ECG.
You can perform ECG spot checks using the app on the watch. When you open the app, touch your fingers to the aluminum case and hold as instructed on the watch for an ECG to be taken.
Again, this can be exported via a PDF.
The PPG sensor also scans for abnormal rhythms continuously, including high and low heart rates. That means it can alert you to possible issues without the need to take manual scans, and if you suffer from a condition, you can better understand potential triggers.
The Fitbit ECG sensor has gained full FDA and CE approval for use in the US and Europe.
Fitbit Charge 6
Staying with Fitbit, the company boasts ECG on its latest Charge 6 fitness tracker – which is retained from last year's Charge 5 (both pictured above).
It's the only fitness tracker form factor that can take an ECG reading – so a good option for those who don't want to wear a smartwatch. You pinch the sides of the case to take the reading, which is delivered to the Fitbit app.
You can also share your results with your doctor, as well as get immediate feedback on whether your heart rhythm is normal or Afib.
Read our full Fitbit Charge 6 review.
Samsung Galaxy Watch 6
The Galaxy Watch 6 is the latest and greatest Samsung smartwatch in town – and ECG measurement is still a big part of the appeal. But you will need a Samsung smartphone to use the feature.
The ECG app can be found on the Galaxy Watch 6 and 6 Classic – as well as Watch 5, Watch 5 Pro, Watch 4 and Watch 4 Classic.
It takes a 30-second reading when you place your finger on the sensor built into the top physical button. You'll also need to remain still with your forearm resting on a flat surface.
Samsung's Health Monitor app is live in the US and South Korea, and it's also received clearance in Europe.
Specifically, it's available in Iceland, Germany, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Hungary, Ireland, Italy, Latvia, Belgium, Lithuania, Netherlands, Greece, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Austria, and the United Kingdom.
What's more, Japan, Indonesia, UAE, Chile, India, and China are all confirmed, too.
Have a read of our full Samsung Galaxy Watch 6 review and our guide on how to take an ECG reading on Samsung smartwatches.
Huawei Watch 4/3 Pro
Huawei now has regulatory sign-off for its ECG feature in Europe, you can perform heart rate rhythm spot checks on its newer smartwatches.
It's been added to the Huawei Watch 4 and the Huawei Watch GT 3 Pro smartwatches, as well as its health superwatch the Huawei Watch D (below).
When you take a heart rate measurement it will show you whether your heart rhythm is normal or Afib on the watch, and save a result to Huawei Health.
In the app you can also log any accompanying symptoms, and also see an ECG graph, which can be shown to your doctor, to assist in any conversations.
Huawei Watch D
It's taken a while but the Huawei Watch D is now available in Europe – and it features blood pressure monitoring and ECG detection.
The Watch D is the company's health smartwatch, and it's a big, powerful beast. It's certainly not a comfortable, sleek smartwatch for casual wear, but as we discovered in our Huawei Watch D review, it's an effective health smartwatch.
This is a device that's designed for medical-grade surveillance of your vitals, and it's likely suited to those who have a pre-existing condition.
As with all things Huawei, it's unlikely we see a release for this one in the US.
Google Pixel Watch 2
It's not just Fitbit's devices that Google enlists to take electrocardiograms, with the Pixel Watch 2 (and the original Pixel Watch) also offering the skill.
Like with the Apple Watch, this is taken through the crown on the outer edge of the watch through a 30-second scan.
Results are then sent to the Fitbit app for your perusal, with a full history and timeline of your readings shown.
Read our extended Google Pixel Watch 2 review.
Garmin Venu 3/Fenix 7 Pro/Epix Pro
Garmin has upped its ECG game – with the feature now live on the brand new Venu 3 smartwatch, and the Fenix 7 Pro and Epix Pro. All of these have the same Elevate 5 heart rate sensor – but the feature is US only for now.
They join the Venu 2 Plus, which was launched in 2022, and debuted Garmin ECG.
Users place their index finger and thumb on the metal edge of the device's bezel, or the top-right button, for 30 seconds to receive a reading. The watch will show the heart rate rhythm, and whether it's sinus (normal) or Afib.
You'll need to set it up in Garmin Connect first, though, which will also be a hub for historical data, as well as the place where you can export individual readings as PDFs.
Withings ScanWatch 2
The Withings ScanWatch 2 is the company's latest mid-range hybrid, with the headline upgrades coming in the form of new skin temperature and breathing data.
The ECG feature hasn't changed much, and it's still one of the most proactive we've tested in this regard. Not only can take off-the-cuff ECG readings to check for AFib, with the results able to be presented in a PDF to show to your doctor, but it will also keep an eye out for irregular heart rhythms.
The optical heart rate sensor checks your heart rate throughout the day for irregular beats, and, if it thinks you may have them, it will suggest that you take an ECG test.
Check out our Withings ScanWatch 2 review.
Withings ScanWatch Light
The Withings ScanWatch Light effectively replaces what was actually the first-ever hybrid smartwatch with ECG functionality, the Withings Move.
Despite the name change, the premise and broad design are the same as the Light - this is the more budget-friendly alternative to the ScanWatch 2 (above).
Luckily, the ECG feature works just as well as before, with the hybrid smartwatch also water resistant up to 50 meters and able to automatically track your daily activity.
There's no compromise on the design, either, with premium materials still used and the small, monochrome OLED display also retained.
Read our full Withings ScanWatch Light review.
Coros Vertix 2 / Apex 2
You may not have heard of Coros, but it's a US-based fitness wearables brand that has Garmin in its sights
The Vertix 2 is the company's new outdoors GPS watch, which offers an enormous 140 hours of GPS battery life, mapping, and training insights.
But up its sleeve is an ECG sensor – but it's not used to take the same type of Afib readings as the other devices in our list.
However, it's not a health feature, like we've seen on other smartwatches. The Coros sensor is designed to be a more accurate check of heart rate variability, which is used to calculate your recovery after workouts. Poor HRV scores can also indicate stress, overtraining, or alcohol intake.
HRV scores are commonplace in fitness wearables but are usually measured via the PPG sensor during sleep.
Read our Coros Vertix 2 review.
How does ECG smartwatch tech work?
An ECG records the tiny electrical signals that are generated by the beating of your heart under your skin, which it presents as a trace. This then allows trained professionals, machines, or wearables to understand more about how your heart is functioning – and determine if there are any abnormalities.
“In the simplest sense, it can tell you the heart rate (how fast), the rhythm (how regular), the state of the conduction system and muscle tissue (heart attacks), and even the level of certain chemicals like potassium in the blood, and the effect of medication,” says Dr. Keith Grimes, GP and Clinical Innovation Director at Babylon Health.
An electrocardiograph in a medical setting usually requires placing electrodes on the skin situated close to the heart, which measures electrical activity produced by the heart as it contracts. The electrical activity is sent to a receiver that records the information, and this is where the heart's rhythm can be analyzed and irregularities can be detected.
But the tech inside the Apple Watch (and other ECG-reading devices you can use at home) works differently.
For example, rather than place electrodes on your skin, the Apple Watch example requires you to hold your finger on the device’s digital crown. Wait for 30 seconds and the electrical activity of your heart draws a red trace across the watch’s screen. Once you’re done, the app will let you know whether the trace captured a normal heartbeat, called a sinus rhythm, or an abnormal heartbeat.
On the Fitbit Sense, when you've opened its ECG app you'll be prompted to place your fingers on the corners of the watch's frame for the same 30 seconds to take a reading. It will then indicate whether you have a normal sinus rhythm, or whether there are signs that you might have atrial fibrillation or just an inconclusive reading.
Samsung's ECG-packing smartwatches use their touch-sensitive button as a sensor that you'll place your finger on for 30 seconds as well. After that, it will measure your heart rate and rhythm, and classify it as sinus rhythm (normal) or AFib.
The biggest difference between an electrocardiograph at a hospital and the ECG tech in your Apple, Fitbit, or Samsung smartwatch is the first is a 12 lead and the latter is a single lead. In the simplest terms, the 12 lead is taking lots of readings about your heart – the single lead is taking one.
That means a single lead ECG has limited capabilities and offers a single view of your heart. It can’t be relied upon to detect all heart rhythm abnormalities – or worsening heart problems. It also can’t be relied upon to detect the electrical changes that take place during a heart attack or abnormal heart structure.
Apple makes this clear, but it’s important to differentiate between what an ECG at the hospital can offer and what tech you use at home can offer.
How can ECG tech save your life?
An ECG carried out by a medical professional can identify many issues with your heart. But ECG devices designed to be used at home aren’t quite there yet.
Here are a few of the ways the ECG tech found in your Apple Watch or Samsung smartwatch can currently save your life though, including the problems that they can identify and the others they might be able to.
Atrial fibrillation is a heart condition that can cause an irregular and abnormally fast heartbeat. It’s common and potentially deadly. It's also intermittent, which makes it difficult to detect. This is the one condition that both Apple and Samsung are FDA-cleared to detect. FDA approval is still pending for Fitbit's new Sense watch to do the same.
ZDNet writer Jason Perlow was part of the early testing of Apple’s Atrial fibrillation detection and identified a problem with his heart in 2018 thanks to the data that was collected.
The reason personal devices are effective at recognizing this particular kind of arrhythmia (irregular heartbeat), and the reason Perlow cites for its effectiveness in his case, is because you can take them at any time.
Unlike getting an ECG at the hospital, you can monitor your heart throughout the day. “Irregularities in heart rate can be episodic, and difficult to capture,” explains Dr. Grimes, “So a personal ECG that you carry with you can help clinicians record when palpitations happen and help with diagnosis.”
This means you can take a 30-second ECG whenever you feel symptoms and also better understand the context of what may have brought them on. For example, if you just got back from a run and you’re feeling a bit off.
Dr. Tony Faranesh, a senior research scientist at Fitbit says the optimal way to identify atrial fibrillation through heart rate tracking is to screen while at rest, making sleep ideal for detection.
On Fitbit's devices, that's done by using its optical-based PPG heart rate sensor. The ECG sensor, like Apple and Samsung, is used for spot checks.
Like Apple, it seems that Fitbit won't be continually scanning for signs of Afib, though Apple and Fitbit both use the PPG sensor to check for irregular rhythms such as high or low heart rate.
Dr. Julia Reynolds, Associate Director at Innovation Agency, tells us that the Kardia Mobile built by startup AliveCor is sometimes even prescribed to patients for this exact reason.
“Individuals may be given a mobile ECG device by their health professional if they are concerned they may have paroxysmal Atrial fibrillation – that’s when it comes and goes. That way, if they are feeling signs and symptoms, they can take their ECG when they are experiencing symptoms.”
How often should I take an ECG reading?
Provided your heart gets a normal sinus rhythm, you’re likely to only need to periodically take an ECG test, just to check everything is in order.
But if you suffer from the feeling of your heart racing, palpitations, or periods of feeling unwell, then you can use the ECG app as and when you need it. And it becomes an incredibly important health tool, right on your wrist.
Fitbit’s Director of Research Algorithms, Conor Heneghan, says that means users can have a better-informed conversation with their doctor.
“The problem with cardiac issues with rhythm is they're so intermittent,” said Heneghan.
“For people who have palpitations or other symptoms, ECG can be a reassurance. And if they feel like something's a bit odd going on physiologically they can capture that moment to speak with their doctor about it,” he continued.
Fitbit also recommends that the ECG feature should only be used by those aged 22 or above.
The problems with false positives – and negatives
ECG devices available to consumers can detect a range of heart problems, whether they’ve been cleared to or not, but that doesn’t mean they should replace a trip to your doctor.
“Reading an ECG is tricky,” Dr. Grimes explains. “Current technology uses machine learning to detect common abnormalities, but personal ECG, like the kind you find on the Apple Watch, is not as accurate as medical devices.”
Personal ECG devices are proven to save lives, but on the flip side, they can still miss major problems or cause people to worry they have issues with their heart when they don’t. Dr. Grimes calls these “false negatives” and “false positives”.
Although many in the medical profession are warning people to be wary of the results they get from their Apple Watch or other ECG devices, having more control over our health at home is going to become more widespread over time.
That means instead of advising against ECG devices, people need to be informed that readings might not always be accurate – but it’s best to head to a medical professional if you see a reading you’re concerned about, to get it checked out.
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