you cant die, but it does kinda feel like a heart attack though and its tough to breath so youll proberly freak out which of course makes the attacks even worse. i had them alot last year when i was taken off prozac, they suck and are scary as hell, but i found that once i first feel one coming on i go outside to get some freash air and have something cold to drink and repeat 'im gonna be fine', when i do that for a while it feels like the panic attack left faster and wasnt as intense.