Yes, thank you, she had a check-up last thursday to make sure everything is OK with the pacemaker, which it is. She is planning a gentle session on the tennis court with a friend tomorrow, to start building up her strength again.
With regard to your own experience, I wonder how much your failure to get beyond 10 miles is simply due to the decline of strength with age, rather than anything to do with your heart condition. I don't feel confident to attempt any race much beyond 10 miles; I entered the Four Fans specifically because I was wanting a race that would test the limits of my current endurance. On the other hand, there are still quite a few M60's who happily go around the toughest AL's . . .