Currently the iPhone application does not connect with a bluetooth Heart Rate monitor, but you can still get Heart Rate data and Stryd Power data in your PowerCenter to analyze.
Our developers are working on integrating Heart Rate into the app but the immediate timeline is unknown for completion. If you would like to be able to view your heart rate data and Stryd Power we do have a recommendation: "iSmoothRun"
iSmoothRun does have the capability to use the Stryd pod as well as sync with a bluetooth heart rate monitor. This data can also be exported to Garmin Connect which will work in the Power Center for better analysis and let you to continue to build your Stryd profile.