I see what you mean about taking the pills as a preventive measure. You are correct in that it takes away a lot of the stress that the fear of having a migraine at difficult times provoques, but doing so often probably takes away some of it´s effectiveness in a real crisis, as you´ve also mentioned. Doing so everytime i went up alone would not be a good idea, surely.
As far as any heart condition, i´ve been doing ECGs for many years, on a yearly basis, and last year did a running one (for around 15 minutes) and no problem at all showed up. I have no idea as to wether the problem you mention would show up in such an exam or not.
This cannot be used as a definite, but motorcycle racing (even at a amateur level, like mine) entails very high levels of physical and mental stress, and i´m gessing if i had a serious heart condition i´d possibly not be here by now, but stranger things have indeed happened (such as Pro athletes dropping dead on a playing field all of a sudden), so who knows?!
Providing the doc says it´s ok, i´ll just keep the "Avamigrans" in hand (as allways) so i can use them if i need too (taking two pills has stopped the symptoms developing into any sort of dangeours levels of visual impairement everytime it´s happened, wich hasn´t been often at all, thankfully).
Thanks.