NO. When your having a heart attack it is hard to breathe.
It's as is King Kong has your body in his hand and he is just squeezing you, he makes it impossible for you to completely fill your lungs. If your having a heart attack, you would know it, you would be on the ground wondering if your going to die in 2 seconds or 2 minutes.
A heart attack is when one of the Arteries going to your heart "completely" clogs up, like the drain in your bathroom sink. Sometimes, as it is getting comletely clogged, the little opening left will get completely blocked for a few seconds then break open again. This will give you a weird pain that normally last less then 90 seconds, and then you will feel fine again as if nothing is wrong. You may get several of these a day, even for a few days, till it gets clogged and is no longer able to clear an opening again, you will then have crushing pain that will not go away, and if you don't get to the hospital soon your heart could stop beating.
If you think your having or going to have a heart attack, you can chew up a few aspirin in your mouth, this will get it in your system faster and help keep the artery clear till you can get to the hospital.