This is an early release of the ALPHA - Heart rate monitor, which can be used with various heart rate measuring systems, like the Mio ALPHA, and Polar H7; as long as they use Bluetooth Low Energy / Smart it should work.
This app currently is in Alpha state, but updates will be provided frequently (as much as possible).
The following Bluetooth Low Energy compliant devices, with Android 4.3 and above, are supported:
Google Nexus 5
HTC Droid DNA
HTC One X+ (Android 4.1+)
Samsung GS4 (Android 4.2+)
Most Bluetooth heart rate sensors should work, including (but not limited to..)
Mio Alpha, Polar H7, BlueLeza HRM Blue, Zephyr HxM Smart, Viiiiva, 60beat Blue, Beets BLU, and Wahoo Blue HR
Live heart rate monitoring
Maps tracking with rate indicator