A lot.

Here are two examples:

Dr. Keyur Parikh – Cardiologist

Dr. Dhiren Shah – Cardiac Surgeon

Cardiologists typically use balloons and stents to open up blockage without opening up the chest through a process called Angioplasty. Patient is typically conscious. Discharged in 1 or 2 days depending on post surgery health stats.

Cardiac Surgeons have minimally invasive techniques but most cardiac surgeons open up the chest to perform the surgery. Patient is given general anaesthesia. Normal words here are CABG, Bypass, Heart Transplant, Heart Failure, etc etc. Most of the time surgeries that a cardiologist can’t do due to complexity is moved over to the Cardiac Surgeon.

I truly hoped this helps!