Audio-only appointments represented almost half of telehealth visits in the study.
The technology developed at the University of Michigan continuously uses data from a single electrocardiogram lead.
Preliminary report of data shows steady level of virtual visits substituting for in-person visits.
Physicians say demystifying data is key
Poll finds less than 1 in 3 people over 50 currently use them for any purpose, and only 28% of people with diabetes use them to track blood sugar levels.