Sorry, I didn't see your post before, possibly because I was on a lot of drugs at the time. The dap has no effect on my heart.
When I first started taking it the ten mg made me a little agitated as if I had drank too much coffee, but it did make me stronger. I currently take sixty mg a day divided as follows:

6am. 10mg
8am. 5mg
10am 5mg
12pm 10mg
2pm. 5mg
4pm. 5mg
6pm. 10mg
8pm. 5 mg
10pm. 5mg
Hope you see some results soon.