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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


Electrocardiogram Sub-Samples

 

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"}
}