Are Palpitations Really Heart Attacks?

I have been dealing with this problem for a while & now that I went to the doctor's office yesterday they told me I have been having these irregular heatbeats called palpitations.I'm 30 year old black man who's B-day is just days away & I'm in the best shape of my life.I don't drink nor smoke nor let people & things stress me out.But when I excercise or maybe if I'm just standing up I get these rapid heart beats that last for a minute or so which have me griping my chest & breathing deeply like I ran from the cops or someone in a nightmare...Now I gotta see what's up with my heart & hope for something good unless my doctor tells me there's something work.But I wanna know are they mini heart attacks & do you think I can die from them?