I had a heart murmur detected during my annual aircrew medical one year, cue downgrade in med cat and a few months waiting for an echocardiogram at Haslar etc. before everything was confirmed as being nothing to worry about and getting my med cat back.
Went for my CAA Class 1 medical, had the usual checks including an electrocradiogram, Doc looked at the trace for 30 seconds, said 'that's nothing to worry about' and signed me off.