I also remember the time between Christmas and New Year being very busy - I thought for a similar reason - people understandably just don't want to be in hospital for Christmas.
E.g., using sensors that are cheap, and are less invasive than EKG electrodes. Kinda like the way Apple watches can now continuously monitor stuff
It is very clear about the fact it cannot detect a heart attack though.
Then there’s these slightly more sophisticated things: https://store.kardia.com/products/kardiamobile6l