ir certainly could be a panic attack, but if this isn't something that has happened before, i'll 2nd (3rd?) the suggestion to see a GP/pdoc.

for me - i've only had these after (1) taking new medication and (2) (bizarrely) eating a new brand of bread. i'm pretty embarrassed about the 2nd time, because i honestly did think i was dying. but it turns out that the increase in fibre or something can mimic the gastrointestinal symptoms, and also kind of lead up to your heart. not fun!

so yeah - i'd mention it to your GP or pdoc. if it is a panic attack, then that's cool, but if it isn't - maybe there is something else that will help you prevent further episodes.