I am not an expert regarding this, but I personally developed endocarditis from a regular teeth cleaning a few years back. The bacteria from your mouth can cause endocarditis, (an infection of the heart valve). My understanding is that if you don't take care of your teeth/gums there is higher bacterial content in your mouth that travel into your blood stream may cause heart issues. I don't think that not getting the root canal is causing your heart issues. You should get the heart ache checked out, to make sure everything is ok. Good luck.
I have heaerd that it is the bacteria in the mouth that is responsible for heart problems. So i would have thought that as long as your root canal is well maintained you shouldn't have any problems.
The thought occurs to me though that you should still get your heart checked out if you are feeling symptoms. It may not be your heart but better to be safe!
All the best