I think with new things like you haven't had a panic attack before, your mind will search on what it knows on symptoms. The mind does this for every new thing. What does this new thing look like that I know more about?

When I had my first panic attack at 6 I had no idea what a heart attack was. I just knew we had a heart that pumped blood and kept us alive, a sort of cool machine. That was what I knew about hearts. So having a panic attack then I didn't think about hearts. Growing up with them I knew from experience they didn't kill you, so I always assumed they only had to do with my mental state.

It's much different if you are hit with one as an adult and never felt that stuff before. I assume you are much more prone then to think it is something physical.