Apple HealthKitV2 Electrocardiogram Export Format
Electrocardiograms (ECG) in HealthKit have a unique data structure for capturing information specific to the participant’s ECG.
Unlike other HealthKit data streams, ECGs do not show on the Apple HealthKit tab within a participant's chart. This data is still available through data exports.
Data Structure
Electrocardiogram Samples
| Field | Description |
|---|---|
HealthKitECGSampleKey |
A unique, auto-generated key for this ECG. |
ParticipantIdentifier |
The identifier of the participant this task was for. Can be used to cross reference with Participants. |
ParticipantID |
The stable, automatically generated, internal system identifier for this participant. Universally unique identifier (UUID). |
StartDate |
The start date of the ECG, in ISO 8601 format. Includes timezone offset information. May be empty if no start date was recorded. |
Date |
The end date of the ECG, in ISO 8601 format. Includes timezone offset information. |
AverageHeartRate |
The user’s average heart rate during the ECG. |
Classification |
The ECG’s classification.
|
NumberOfVoltageMeasurements |
The number of voltage measurements associated with this sample.
|
SamplingFrequency |
The frequency at which the Apple Watch sampled the voltage. |
SymptomStatus |
A value that indicates whether the user entered a symptom when they recorded the ECG. |
SourceIdentifier |
A unique identifier for the source object. |
SourceName |
The name of the source app which generated the reading. In the case of a “com.apple.health.*” SourceIdentifier, this is the name of the Apple Device used to generate the reading (e.g. “Chris’ iPhone”). |
SourceOperatingSystemVersion |
An arbitrary string representing the version of the software running on the device, if applicable. |
SourceProductType |
An arbitrary string representing the hardware version of the device, if applicable. |
SourceVersion |
The version of the source app which generated the reading. In the case of a “com.apple.health.*” SourceIdentifier, this is the version of iOS or WatchOS on the device used to generate the reading. |
DeviceFDAIdentifier |
The device identifier portion of the US Food and Drug Administration’s Unique Device Identifier (UDI), if applicable. |
DeviceFirmwareVersion |
An arbitrary string representing the current version of the firmware running on the device, if applicable. |
DeviceHardwareVersion |
An arbitrary string representing the hardware version of the device, if applicable. |
DeviceLocalIdentifier |
An identifier that uniquely identifies the device object on the hardware running this code, if applicable. |
DeviceManufacturer |
Manufacturer of the device used the generate the reading, if applicable. |
DeviceModel |
Model of the device used the generate the reading, if applicable. |
DeviceName |
The user-facing name for the device, if applicable. |
DeviceSoftwareVersion |
An arbitrary string representing the version of the software running on the device, if applicable. |
Metadata |
Additional XML metadata inserted by the source application. |
InsertedDate |
The creation date of the entry, in ISO 8601 format. Is always in UTC. |
Electrocardiogram Sub-Samples
| Field | Description |
|---|---|
HealthKitECGSampleKey |
A unique, auto-generated key for this ECG. |
ParticipantIdentifier |
The identifier of the participant this task was for. Can be used to cross reference with Participants. |
MicroVolts |
The microvolts unit of electric potential difference. |
TimeSinceSampleStart |
The time of the measurement relative to the sample’s start time. |
If a participant re-syncs their device, you may observe duplicate samples. HealthKit samples are immutable, so when doing data analysis, your team will need to remove any samples that have the same HealthKitECGSampleKey and ParticipantIdentifier as another sample.
Sample CSV Exports
Electrocardiogram Samples
HealthKitECGSampleKey,ParticipantIdentifier,StartDate,Date,AverageHeartRate,Classification,NumberOfVoltageMeasurements,SamplingFrequency,SymptomStatus,SourceIdentifier,SourceName,SourceOperatingSystemVersion,SourceProductType,SourceVersion,DeviceFDAIdentifier,DeviceFirmwareVersion,DeviceHardwareVersion,DeviceLocalIdentifier,DeviceManufacturer,DeviceModel,DeviceName,DeviceSoftwareVersion,Metadata,InsertedDate
d3e7dd07-5060-53fd-a58f-474b2dfbd7ec,256263d8-3ffc-eb11-aaae-0afb9334277d,2021-12-07T16:31:46-05:00,2021-12-07T16:32:16-05:00,61,SinusRhythm,15404,0,Not Set,com.apple.NanoHeartRhythm,ECG,8.1.0,"Watch4,4",1.9,,,"Watch4,4",,Apple Inc.,Watch,Apple Watch,8.1,"{""HKMetadataKeySyncVersion"":""0"",""HKMetadataKeyAppleECGAlgorithmVersion"":""1"",""HKMetadataKeySyncIdentifier"":""89C9E3B3-1B75-4F06-AC48-AFF179EC5266""}",2021-12-09T22:18:48Z
b407ceb2-d365-55ec-bfab-c9bbd9a60711,256263d8-3ffc-eb11-aaae-0afb9334277d,2021-12-09T15:13:26-05:00,2021-12-09T15:13:56-05:00,64,SinusRhythm,15404,0,Not Set,com.apple.NanoHeartRhythm,ECG,8.1.0,"Watch4,4",1.9,,,"Watch4,4",,Apple Inc.,Watch,Apple Watch,8.1,"{""HKMetadataKeySyncVersion"":""0"",""HKMetadataKeyAppleECGAlgorithmVersion"":""2"",""HKMetadataKeySyncIdentifier"":""AEBF344A-3CD2-4C9B-905F-3C793E6E831A""}",2021-12-09T22:18:48Z
2992a11b-8783-5221-8810-4f4d402c2f16,256263d8-3ffc-eb11-aaae-0afb9334277d,2021-12-09T15:20:16-05:00,2021-12-09T15:20:46-05:00,74,SinusRhythm,15404,0,Not Set,com.apple.NanoHeartRhythm,ECG,8.1.0,"Watch4,4",1.9,,,"Watch4,4",,Apple Inc.,Watch,Apple Watch,8.1,"{""HKMetadataKeySyncVersion"":""0"",""HKMetadataKeyAppleECGAlgorithmVersion"":""2"",""HKMetadataKeySyncIdentifier"":""40B3F71C-A280-4C5B-B4BA-FB6327BCDB63""}",2021-12-09T22:18:48Z
Electrocardiogram Sub-Samples
HealthKitECGSampleKey,ParticipantIdentifier,MicroVolts,TimeSinceSampleStart
d3e7dd07-5060-53fd-a58f-474b2dfbd7ec,256263d8-3ffc-eb11-aaae-0afb9334277d,-65.85879517,0
d3e7dd07-5060-53fd-a58f-474b2dfbd7ec,256263d8-3ffc-eb11-aaae-0afb9334277d,-20.15280342,5.17453024
d3e7dd07-5060-53fd-a58f-474b2dfbd7ec,256263d8-3ffc-eb11-aaae-0afb9334277d,-15.79679871,12.60817041
d3e7dd07-5060-53fd-a58f-474b2dfbd7ec,256263d8-3ffc-eb11-aaae-0afb9334277d,47.36212921,19.47508558
Sample JSON Export
Electrocardiogram Samples & Sub-Samples
{
"HealthKitECGSampleKey":"d3e7dd07-5060-53fd-a58f-474b2dfbd7ec",
"Device":
{
"FDAIdentifier":"",
"FirmwareVersion":"",
"HardwareVersion":"Watch4,4",
"LocalIdentifier":"",
"Manufacturer":"Apple Inc.",
"Model":"Watch",
"Name":"Apple Watch",
"SoftwareVersion":"8.1"
},
"SubSamples":
[
{"MicroVolts":-65.858795166015625,"TimeSinceSampleStart":0.0},
{"MicroVolts":11.933460235595703,"TimeSinceSampleStart":7.4784328642069227},
{"MicroVolts":-15.733985900878906,"TimeSinceSampleStart":12.637383035374667},
{"MicroVolts":-33.990604400634766,"TimeSinceSampleStart":29.997474324838343}
],
"Source":
{
"Name":"ECG",
"Identifier":"com.apple.NanoHeartRhythm",
"Version":"1.90",
"OperatingSystemVersion":"8.1.0",
"ProductType":"Watch4,4"
},
"AverageHeartRate":61,
"NumberOfVoltageMeasurements":15404,
"SamplingFrequency":0,
"Classification":"SinusRhythm",
"Date":"2021-12-07T16:32:16-05:00",
"InsertedDate":"2021-12-09T22:18:48Z",
"ParticipantIdentifier":"256263d8-3ffc-eb11-aaae-0afb9334277d",
"StartDate":"2021-12-07T16:31:46-05:00",
"SymptomStatus":"Not Set",
"Metadata":{"HKMetadataKeySyncVersion":"0","HKMetadataKeyAppleECGAlgorithmVersion":"1","HKMetadataKeySyncIdentifier":"89C9E3B3-1B75-4F06-AC48-AFF179EC5266"}
}