I am so sensitive that I have even a problem with decaf. It still has some caffeine in it.
Another thing that has helped me is drinking water. I still am not up to the 8 glasses a day, but before drinking very little. I am really working on it. I have never drank much and my parents didn't either. My mom had alzheimers real bad. So I am doing all I can to avoid that. And I read that not enough water can affect your heart and also dementia.

If you are having heart issues, try eliminating the coffee and drink water. Of course, no colas, chocolate or anything else with caffeine. Mountain Dew has more than colas. Let us know what happens.