How Cardio Analytics Works

Seamless HealthKit integration for automatic cardiovascular data sync with complete privacy and control

HealthKit Sync Overview

Cardio Analytics integrates with Apple HealthKit to automatically import and track 11 cardiovascular and mobility metrics. All data processing happens locally on your iPhone with no cloud uploads or external servers.

1

Authorize HealthKit Access

Grant permission to read specific data types from Apple Health. You choose exactly which metrics to share with granular control.

2

Automatic Background Sync

Cardio Analytics uses efficient background synchronization to fetch new data automatically without draining your battery.

3

Local Processing & Alerts

All metrics are processed on-device. Receive evidence-based alerts, track trends, and export reports when you choose.

HealthKit Data Types

Cardio Analytics uses official Apple HealthKit identifiers for all cardiovascular and mobility metrics:

Heart Rate Metrics

  • HKQuantityTypeIdentifier.heartRate - Current heart rate (beats/min)
  • restingHeartRate - Resting HR baseline (Apple Docs)
  • walkingHeartRateAverage - Average HR during walking

Cardiovascular Metrics

  • bloodPressureSystolic + bloodPressureDiastolic - Paired BP readings (Apple Docs)
  • heartRateVariabilitySDNN - Overall HRV variability
  • heartRateVariabilityRMSSD - Short-term vagal tone (where available)
  • oxygenSaturation - SpO₂ as fraction (display as %) (Apple Docs)

Body Composition

  • bodyMass - Weight in kg
  • BMI calculated from height and weight

ECG & Atrial Fibrillation

  • electrocardiogramType - ECG recordings with HKElectrocardiogram.Classification (Apple Docs)
  • atrialFibrillationBurden - AF burden percentage (where available) (Apple Docs)

Fitness & Mobility

  • vo2Max - Cardio fitness (mL/kg/min) (Apple Docs)
  • walkingSpeed - Average steady walking speed (m/s) (Apple Docs)
  • walkingAsymmetryPercentage - Gait imbalance % (Apple Docs)
  • stairAscentSpeed - Stair climbing speed (m/s) (Apple Docs)

Background Sync Technology

Cardio Analytics uses Apple's recommended patterns for efficient, battery-friendly data synchronization:

Anchored Object Queries

Cardio Analytics uses HKAnchoredObjectQuery for efficient delta synchronization, fetching only new or modified data since the last sync (Apple Docs).

// Example: Anchored query for efficient delta sync
let query = HKAnchoredObjectQuery(
    type: heartRateType,
    predicate: nil,
    anchor: lastAnchor,
    limit: HKObjectQueryNoLimit
) { (query, samples, deletedObjects, newAnchor, error) in
    // Process only new/changed samples
    self.processSamples(samples)
    self.lastAnchor = newAnchor
}

Background Delivery

Using HKHealthStore.enableBackgroundDelivery, HealthKit can automatically wake the app when new data becomes available (Apple Docs).

  • Immediate updates - Fresh cardiovascular data without manual refresh
  • Battery efficient - System-managed wake-ups minimize power consumption
  • Reliable delivery - Works even when app is closed

📱 Required entitlement: com.apple.developer.healthkit.background-delivery (Docs)

Write-Back to HealthKit

User-entered data (weight, blood pressure) can be written back to HealthKit for consistency across all health apps and devices.

  • Unified health record - Data entered in Cardio Analytics appears in Apple Health
  • Clinician visibility - Doctors using HealthKit-connected systems see consistent records
  • Cross-app compatibility - Other health apps can access your Cardio Analytics entries

Privacy & Granular Permissions

You control exactly which data types Cardio Analytics can access. HealthKit authorization is granular - approve or deny each metric individually.

What Cardio Analytics Does NOT Do:

  • ❌ No cloud uploads - all data stays on your device
  • ❌ No external servers - no data transmission to third parties
  • ❌ No account required - no email, username, or personal info collection
  • ❌ No tracking or analytics - we don't know who you are or how you use the app

What You Control:

  • ✅ Choose which metrics to share (e.g., share HR but not weight)
  • ✅ Revoke permissions anytime in iOS Settings → Privacy → Health
  • ✅ Export reports only when you decide to share with your clinician
  • ✅ Delete all app data anytime by uninstalling

Read Full Privacy Policy

Device Compatibility

Cardio Analytics works with any device or app that writes to Apple HealthKit:

Apple Watch

Heart rate, HRV, SpO₂, ECG, VO₂ Max, walking metrics, stair speed

Connected BP Monitors

Bluetooth blood pressure cuffs (Omron, Withings, QardioArm, etc.)

Smart Scales

Weight and BMI from connected scales (Withings, Fitbit Aria, etc.)

Manual Entries

Add BP, weight, or other metrics directly in Apple Health app

Other Fitness Trackers

Any device syncing heart rate or fitness data to HealthKit

Medical Devices

FDA-cleared devices with HealthKit integration

💡 Missing metrics? If your device doesn't record certain metrics (e.g., SpO₂ on older watches), Cardio Analytics automatically hides those cards.

Experience Effortless Health Tracking

Download Cardio Analytics and let Apple HealthKit automatically sync your cardiovascular data. No manual entry required - just monitor, analyze, and share with your doctor.

Download on App Store