Heartin.net, is creating a smart garment with built-in sensors that bring wellness solutions, mental health monitoring, and cardio-diagnostic to the mass market. You can check details at http://presentation.heartin.net
Heartin will export you HR data to HealthKit, which can be used in future to help you understand better yourself for doctors, if you allow it.
disclaimer: seek a doctor’s advice in addition to using this app and before making any medical decisions.