In recent years, a type of artificial intelligence known as “deep learning” has allowed tech companies to vastly improve computer vision and speech understanding. Now, interest in applying this software to medical data is growing as health systems look to reduce costs and take advantage of large amounts of information generated by internet-connected consumer-health trackers and medical devices.

The Wall Street Journal talked with Brandon Ballinger and Johnson Hsieh, the developers of Cardiogram, a consumer heart rate-tracking...