As others have said, it is better to approach testing enthsuiastically in order to avoid hiding any heart troubles. If you're a 'tough guy', remember, there's no shame in crying, wincing, or asking for a smaller needle because no amount of pretending that it's fine can make up for the fact that you're lying on a bed while a bunch of eggheads (no disrespect to doctors) you don't know poke you. So get into it! If it turns out to be nothing, no-one cares, but if there is a problem, then you've likely saved your own life.
-Penguin