I have a doubt. Since I read Clare Weeks book "Self-help with your nerves" I have learn to deal with my anxiety and panic attacks in a "let it come, ride it and back to normal, without taking medication and so far has worked for me. So when I sense a panic attack or anxiety and my heart still pounding fast I let it go up and wait until the panic subsides.

Recently I had a lots of anxiety because I had to do a upper endoscopy and I was very worried, so a couple of days after the test I had heartburn and my heart started beating fast and ended up in A&E with a panic attack, I couldn't wait until the heart calmed down, couldn't managed I was too afraid my heart was beating at 130 bpm. They did an ECG and the doctor said it was a sinus tachycardia and gave me a tranquilizer which I didn't take because once I am checked out and find out that it's anxiety I calm down.

My question is:

Could it be dangerous in the long term for the heart to beat fast during panic attacks. I still want to use the same technique but once you ridge over 100 bpm is the heart working harder than it should? I would appreciate if someone could explained this? Many thanks.