Take a look at the oher thread on the 182 failed go around with a pilot with a heart condition that he didn't tell the DAME about
He had a heart condition that was detected in the autopsy. It was not detectable in normal tests for a class 1 medical (does that include ECG?)
It is not clear that the pilot knew he had the condition - the lack of information in the report suggests he did not. The report also says that there is no evidence that the condition contributed to the accident.