With my setup there are many problems, not in it's principle which is sound (well S4 sounds) but in practical:

It has problems detecting heart sounds with obese people, women with ample breast.

Some smart guys have a better proposal: A smart toilet seat!

The toilet seat–based cardiovascular monitoring system is completely self-contained, battery-powered, wireless, and cleanable with all sensors and electronics instrumentation integrated inside of the seat. It can measure the electrocardiogram (ECG), photoplethysmogram (PPG), and the ballistocardiogram (BCG).

https://mhealth.jmir.org/2019/1/e12419/

I wish them a lot of success :-)