Key points from article :
Cardiologists analyse heartbeat scans incorrectly in one in five cases.
False negatives send patients home with risk of a heart attack.
False positives result in unnecessary and expensive operations.
Artificial intelligence system developed at the John Radcliffe Hospital is more accurate.
It can pick up details in the scans that doctors can't see.
Technology will start to be available to NHS hospitals for free this summer.
Could save the NHS more than £300m a year.
The system is also being commercialised by a start-up company called Optellium.
