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Fitbit ECG Data Export Format

  • Updated

The Fitbit Electrocardiogram (ECG) data export reports a participant’s ECG reading taken from their Fitbit wearable device. The Fitbit ECG app allows participants to create and record an ECG by taking a 30-second reading on their wrist-worn Fitbit device. This is made possible by the electrical sensors on certain Fitbit products that can detect and analyze heart rhythm data for signs of atrial fibrillation (AFib). While the assessment cannot provide a definitive diagnosis of AFib, the results can lead to a more productive conversation between a participant and their healthcare provider.

The data in the Fitbit export is obtained through the Fitbit API. The available data will vary based on the device capabilities and the user's privacy settings. See the Fitbit "Electrocardiogram (ECG)" documentation for more information about using and interpreting Fitbit data.

Table of Contents

Fitbit ECG

Field Description
FitbitEcgKey Unique key for this ECG reading, used to relate records in the Waveform CSV together.
ParticipantID The stable, automatically generated, internal system identifier for this participant. Universally unique identifier (UUID).
ParticipantIdentifier The identifier of the participant this task was for. Can be used to cross reference with Participants.
InsertedDate The creation date of the entry, in ISO 8601 format. Is always in UTC.
StartTime The date and time when the reading was started on the device.
AverageHeartRate The average heart rate of the user during the reading.
ResultClassification

See Classification of ECG results for more information.

Supported: Atrial Fibrillation | Normal Sinus Rhythm | Inconclusive | Inconclusive: High heart rate | Inconclusive: Low heart rate
WaveformSamples An array of integers representing the ECG waveform, in JSON only. See Fitbit ECG Waveform for CSV representation of waveform sample data.
SamplingFrequencyHz

The frequency in hertz at which the Fitbit ECG app sampled the voltage.

Supported: 250
ScalingFactor

The scaling factor used to convert waveform samples to ECG voltages in mV (mV = waveformSamples / scalingFactor).

Supported: 10922
NumberOfWaveformSamples

The total number of samples in the reading.
LeadNumber

The ECG lead being used to take the reading. The compatible Fitbit wrist-worn devices contain a single-lead. Therefore, the leadNumber will always be 1.

Supported: 1
FeatureVersion The version of the ECG app running on the device. The format of the compatible wrist-worn device components’ version [x.xx-x.xx-x.xx] represents app-service-web respectively.
DeviceName

Hardware name of the compatible wrist-worn device used to take the reading.
FirmwareVersion Firmware running on the compatible wrist-worn device used to take the reading.

Fitbit ECG Waveform

Field Description
FitbitEcgKey Unique key for the associated ECG reading.
Index Indexes correct order of waveform samples for this reading.
WaveformSample An integer representing the ECG waveform.

Sample CSV Exports

In the CSV export, the waveform sample data is exported in a separate file from the ECG reading data.

FitbitECG:

FitbitEcgKey,ParticipantID,ParticipantIdentifier,InsertedDate,StartTime,AverageHeartrate,ResultClassification,SamplingFrequencyHz,ScalingFactor,NumberOfWaveformSamples,LeadNumber,FeatureVersion,DeviceName,FirmwareVersion
7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0,7e6135ff-4ede-ed11-a178-9ccd120ce8c9,aaf84dbd-4ede-ed11-a178-9ccd120ce8c9,2023-04-21T19:14:00Z,2023-02-07T16:19:00.304,49,Inconclusive: Low heart rate,250,10922,7500,1,2.11.0-2.13-2.16,Sense 2,20001.184.52

FitbitECG_Waveform:

FitbitEcgKey,Index,WaveformSample
7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0,0,0
7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0,1,11593
7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0,2,23106
7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0,3,32767

Sample JSON Export

ECG & Waveforms:

{
 "FitbitEcgKey": "7e6135ff4edeed11a1789ccd120ce8c9-1862dbf0ad0",
 "StartTime": "2023-02-07T16:19:00.304",
 "AverageHeartRate": 49,
 "ResultClassification": "Inconclusive: Low heart rate",
 "WaveformSamples": [
  0,
  11593,
  23106,
  32767,
  ...
  ],
 "SamplingFrequencyHz": 250.0,
 "ScalingFactor": 10922.0,
 "NumberOfWaveformSamples": 7500,
 "LeadNumber": 1,
 "FeatureVersion": "2.11.0-2.13-2.16",
 "DeviceName": "Sense 2",
 "FirmwareVersion": "20001.184.52",
 "ParticipantID": "7e6135ff-4ede-ed11-a178-9ccd120ce8c9",
 "ParticipantIdentifier": "aaf84dbd-4ede-ed11-a178-9ccd120ce8c9",
 "InsertedDate": "2023-04-21T19:14:00Z"
}

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