You should first and foremost consult with your doctor. He/she should be able to tell you if your heart is healthy enough for rigorous physical activity. If exercise is a trigger for you, you and your doctor might want to discuss treatment options to minimize the risk of having an event while training. Your doctor ultimately knows best, and if he/she gives you the go ahead and you try it but don't feel good doing it, you need to be comfortable enough with yourself to know what's best for you.
Good luck! I always admire those who have these scary heart problems but want to push themselves to the limit anyway. Hopefully I'll be able to start doing the same thing again in a little while.
I was resently diagnosed with PSVT. I was in a high cardio martial arts, and my doctor recommended that I quit. When I said that I wanted to stay in martial arts, he told me that as long as I went into a low cardio, non belted system (belt testing can be extremely stressful in some dojos), I could get back into martial arts. Don't get me wrong, Tournaments would be a stupid thing to do, but if your doctor says that you can do martial arts, I would go for it. If someone in your area does Tai Chi, I would start with that. It is a soft martial art, with little or no contact, and low cardio. If you do fine, then look at going into the style that you like. And above all else TALK to you teacher. let him know before you start your problem, and make sure that he will make modifications to acomidate your needs.
I am looking at getting a wrist heart monitor for when I go back into martial arts, so that I can stop if my heart rate looks like it is going to high, or won't come down.
I sincerly hope things work out for you,