If the myocarditis was a long time ago and you had no problems and have lived a normal life since I am not sure why you are being referred. I am not an AME but know people have got Class 1s with no investigations if they had no heart failure or arrythmias....
My reading of the CAA's current rules is that you are OK to go if the pathology has resolved and you have a normal post pericarditis echo (to 'exclude heart failure'). You will have an ECG anyhow so that is irrelevant
Not sure why you had an angio, and there may be more to it, but might be worth checking the AME, who may not be a consultant cardiologist, isnt running for cover
PM if you wish