---
title: HKMetadataKeyHeartRateEventThreshold
framework: healthkit
role: symbol
role_heading: Global Variable
path: healthkit/hkmetadatakeyheartrateeventthreshold
---

# HKMetadataKeyHeartRateEventThreshold

A key that records the threshold of high or low heart rate events in beats per minute.

## Declaration

```swift
let HKMetadataKeyHeartRateEventThreshold: String
```

## Discussion

Discussion The value for this key contains an HKQuantity object with count/time units, described in HKUnit. This metadata key is used by highHeartRateEvent and lowHeartRateEvent category samples.