I cannot comment on the CAA's position but as this form of heartblock can lead to complete heartblock it would not surprise me that any known episode might lead to withdrawal of your medical. The treatment is to have a pacemaker fitted but be guided by your cardiologist. I can't see your ECG (rightly so) but the bradycardia could have occurred during an episode of heartblock - an abnormally slow pulse rate is often what first brings the condition to light. Again, I cannot comment definitively, but the SVTs may be a compensatory mechanism. All the above mentioned need to be properly diagnosed and treated as necessary by a Consultant Cardiologist. I wish I could be more helpful and hopeful for you but it is a long time since I worked in an adult cardiology unit so am not fully up to date with recent advances. I'm sorry to be such a pessimist. I hope you will be able eventually to continue flying.
I've just noticed that you do not say whether or not your medical certificate was reissued after your medical or what advice you were given other than the probability of needing a pacemaker. If you haven't already done so, get yourself referred to a Consultant Cardiologist as soon as possible.