I don't have a good explanation what why you would feel it beating harder. the primary purpose heart patients sleep with a stack of pillows is because they often get short of breath if they get flat. Fluid at the bottom of the lungs is one of the features of heart failures. That why cardiologist always ask how many pillows a person sleeps with.
There is a psychological component I'm sure of being HYPERaware of our hearts. I spent a lot of time holding my hand over my heart... like I could in any way protect it. At 40 years old, I took up a blankie again after about 35 years. Better than trying to drink away my problems which doesn't help either and can do more harm.
You won't be able to "forget" it- nor should you. Taking care of it ALL the time is part of having heart problems that you are trying to NOT let progress further. Sometimes I feel like I am trying to stop a moving train... but I will not give up. Some people take an antianxiety agent. If you can do it without, all the better. Find ways to cope. I recommend an ongoing conversation with God. Coming here, there is always some encouragement and usually some answers to questions that will not stop rolling around in your head. Take care of yourself.
Thanks for your insights and honesty. Never thought I would find myself battling this as I've had no contributing factors except prehypertension. I've had a few conversations with God. It's tough trying to find a balance between suffering with grace and not succumbing to the problem. I wish you all the best.