this sounds exactly the same issues as myself. Had the enlarged heart muscle spiel also, had a scan which showed up, was told the same thing that it will decrease with time on the medication. I have been laying off the running for about 6 months and I am now going to get back into it with some gentle gym work and build it up again. Have just put a call in to the docs about the certificate for Paris. Wont pay up the entrance fee just yet unless they give me the go ahead. They did seem to think that it would be good to start training again which is good news.
Just found this post, have entered the Paris marathon and need a docs certificate to enter. Have got a place also! Has anyone had any issues getting a docs certificate for marathons with high blood pressure? I have been taking Amlodipine and Ramipril also, hate taking them, but they are definately bringing the BP right down,