JP.Pilot,
I had a flat T wave, which didn't show up on a class 1 Ecg until some 5 years after my Class 1 was initially completed.
As with yourself, I was given a contact list of CAA recognised cardiologists. In my case, I spoke with my nearest by phone and he stated my issue could possibly be resolved with an exercise ECG. On completion of this he then completed his report to the CAA describing it as a minor birth abnormality, which got my medical re-instated in a matter of a few weeks start to finish.
All of this made me very happy, and the cost was not unreasonable. Likewise the CAA were remarkably good given their reputation.
My advice is to speak with one of the cardiologists and take their guidance on how to progress.
Hope this helps,
Obs cop