I had my medical temporarily suspended because of ventricular ectopic beats, until further examination carried out with ECG / stress treadmill. (CAA just loves to be trebly sure !!!)
Exercise suppressed the irregular heartbeat and the consultant said that around 60% of the population do not have a heartbeat that conforms to the textbook. Furthermore the vast majority of the non-conformers are in perfect health. Needless to say the episode created a fair amount of anxiety, because suddenly I started to realise that maybe I wasn't immortal after all.
Sometimes my ECG is textbook and sometimes not, but so far the grim reaper has not got me and my medical remains valid.
Chill out and don't worry