The heart-rate data is used for internal research that helps us offer and improve the product and (if you opt-in) for the mRhythm study with UCSF.

• One example of this ‘internal research’ is Cardiogram’s tagging feature. We use sophisticated machine learning techniques to identify spikes in heart rate. To do this analysis, heart rate data is uploaded to our web server, so that Cardiogram can do analysis for you (e.g. identify spikes in heart rate for you to tag) and can continue to improve our algorithm.
  
  All of these internal projects are health-related. We won’t share an individual’s data with anyone unless we get his or her explicit permission. To be absolutely clear, data will not be used or sold for advertising or marketing. 
• If you opt-in to mRhythm study, your heart rate data will be shared with the UCSF (University of California San Francisco) team for the purposes of validating how well the Apple Watch can detect atrial fibrillation.
  
  As part of the mRhythm study, you will need to create a Health eHeart account and be asked a few additional questions about your medical history–this data will be managed by UCSF and stored separately from the Cardiogram heart rate data.  

You can see additional details in our privacy policy and learn more about the mRhythm study here. It’s very important to us that Cardiogram users understand and are comfortable with how their data is used, so if you have further questions, please let us know!