The CAA will act on anything abnormal showing up on an ECG. Having said that (and having just gone thru the process) it is strictly a set procedure to clear themselves before assessing you fit to return to duty. They concentrate on two types of anomally; muscular and electrical. Either way you would go thru a series of tests resulting in the vast majority of cases in being returned to flying. Mine was electrical (ectopic0 my colleagues was a murmur. For your own piece of mind it's worth knowing what is going on with your self. If your dad is a doc then you're better placed than most. The biggest problem, believe me is without a doubt, the fact that if you are prepared to remain grounded if they find and investigate this via the NHS, then you are looking at 3-4 months minimum!! I immediately chose private and the whole thing was over in 4 weeks. All the tests are simple non invasive(electrical). Monitor/blood test/echo/stress ecg. Don't be alarmed they are there to get you back to flying....believe me .
Good luck.
PS if you don't reveal it to the CAA but advertise it elsewhere (ie your GP etc) then if you are insured, it could be null and void. By law you are to report any doubts regarding your fitness over 20 days old, to the CAA.
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Thermal runaway.