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Can Fitbit Detect AFib?

Researchers track whether wearable fitness devices such as Fitbit can detect atrial fibrillation (AFib).

As of 2019, there were 28 million active users of the physical activity tracker, Fitbit,1 and at least 19% of Americans owned a wearable activity tracker.2

Fitbit devices are popular fitness trackers, and the market for activity-tracking devices is only expected to grow.

The forecast for wearables activity tracker shipments worldwide is expected to reach 631.7 million shipments by 2024.3

Many different models of Fitbit devices

Usually, activity trackers such as Fitbit are worn on the wrist like a watch. There are many different models of Fitbit devices.

Depending on the type, the wearables can track a variety of physical data, such as exercise, intensity, inactivity, steps taken, heart rate, blood pressure, and even the amount and quality of sleep. 

Measuring physical data

Fitbits use different tracking sensors to measure physical data. Most wearables use accelerometers or gyroscopes to measure activity levels.

Global positioning systems (GPS) and barometers are also used to accurately measure activity and movement.

The different sensors all have differing levels of accuracy but do not use as much battery life.4

Delivering health data

Activity trackers also measure health data such as heart rate. Heart rates are typically measured by an electrocardiogram (ECG) or a photoplethysmograph (PPG).

ECG sensors measure the heart’s electrical activity to determine heart rates.

The ECG sensors most commonly found in activity trackers worn on the wrist are not as accurate as those determined from a chest-strap sensor.

PPG sensors measure the change in blood vessel volume to determine heart rates. Studies have shown that both sensors have acceptable accuracy when compared with clinical ECG measurements.4

Activity trackers can also be used to measure blood pressure, fluid electrolytes, and cardiac output, but are not commonly available in wristband form.

The potential value of fitness trackers to monitor health conditions

Healthcare practitioners quickly realized the potential value of fitness trackers as a means to monitor health conditions.

Because they provide a more accurate assessment of a person’s activity levels, healthcare practitioners could rely on data from the health trackers instead of foggy memories.

Data on exercise intensity would no longer be subjective but could be quantified for real-time assessment.

Fitness trackers also have value as motivators of healthy behaviors and can help wearers set and reach their fitness goals.

Because heart disease and heart-related health concerns make up the top three causes of death globally (WHO), healthcare practitioners are especially keen to make full use of their data.

Physical activity trackers like Fitbit have great potential to identify difficult-to-detect health conditions.

The atrial fibrillation (AFib) condition

One such common, but difficult-to-detect condition is atrial fibrillation (AFib).

Atrial fibrillation is an abnormal heartbeat. It occurs when the upper chambers of the heartbeat are irregular, and out of sync with the lower chambers5  

AFib can lead to stroke or heart failure ( AFib affects up to 34 million people worldwide but is difficult to detect.6 Often people experiencing AFib do not show any outward symptoms.

Because of the prevalence and the popularity of activity trackers, healthcare practitioners wondered if Fitbit detects AFib.

To determine if can Fitbit detect AFib, healthcare practitioners at Fitbit conducted a large-scale clinical trial in 2020 called the Fitbit Heart Study.7

The Fitbit Heart Study

Participants in the Fitbit Heart Study wore Fitbit activity trackers and reported heart data.

Any participant who showed signs of AFib was alerted and connected with a healthcare practitioner for a virtual appointment.

Fitbits’ sensors use photoplethysmography (PPG) technology to measure blood flow and heart rates. From this, the Fitbit algorithm calculated heart rhythm, which allowed it to detect atrial fibrillation if it occurred.7

Results from the study

The Fitbit Heart Study showed that Fitbit’s algorithm was 98.8% successful in AFib detection, and 100% accurate in identifying normal heart rhythms. The FDA granted 510(k) clearance for the device.8

The AFib algorithm is available to users of the Fitbit Sense, the company’s first wearable with an ECG app.

The device contains an electrodermal activity sensor for stress management and up to six hours of battery life. 

While an activity tracker is not a substitute for regular check-ups with your healthcare practitioner, it did answer the question, ‘Can Fitbit detect AFib?’ with a resounding yes.

It is important to remember that activity trackers can be part of a holistic personal health program.

The data they provide helps users get up and leave the sedentary lifestyle behind them.

Always consult your healthcare practitioner before beginning any new diet or exercise plan.


  1. Smith, Craig, et al. “60 Amazing Fitbit Statistics.” DMR, 11 July 2020,
  2. Balbim, Guilherme M, et al. “Using Fitbit as an MHealth Intervention Tool to Promote Physical Activity: Potential Challenges and Solutions.” JMIR MHealth and UHealth, vol. 9, no. 3, 2021, doi:10.2196/25289.
  3. Vailshery, Lionel Sujay. “Wearables Shipments Worldwide 2014-2024.” Statista, 14 Jan. 2021,
  4. Bayoumy, Karim, et al. “Smart Wearable Devices in Cardiovascular Care: Where We Are and How to Move Forward.” Nature Reviews Cardiology, 2021, doi:10.1038/s41569-021-00522-7.
  5. “Atrial Fibrillation.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 20 June 2019,
  6. Tison, Geoffrey H., et al. “Passive Detection of Atrial Fibrillation Using a Commercially Available Smartwatch.” JAMA Cardiology, vol. 3, no. 5, 2018, p. 409., doi:10.1001/jamacardio.2018.0136.
  7. “Fitbit Announces Large-Scale Study to Identify Atrial Fibrillation.” Fitbit, Inc.,
  8. “Fitbit Receives Regulatory Clearance in Both the United States and Europe for ECG App to Identify Atrial Fibrillation (AFib).” Business Wire, 14 Sept. 2020,

Rebecca Blankenship BSc
Rebecca Blankenship BSc
Rebecca Blankenship is a freelance technical writer. She reviews, edits, and authors internal quality documentation required for regulatory compliance. She has twenty years experience in industrial pharma/medical device quality management systems and an honors BSc in chemistry. She is a natural born rule follower and enjoys applying this strength to help others be audit ready to meet regulatory requirements. She also loves learning about the latest scientific discoveries while writing for Medical News Bulletin. Her free time is spent as a full-time mom, encouraging can-do attitudes and cooperation in her three children.


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