After being leaked, the song premiered via international streaming on February 24, 2013 and was exclusively released on iTunes a few hours later in the United States; it was released to the Amazon MP3 store on February 26. Other major retailers began selling it on 5 March 2013. The song received positive reviews from contemporary music critics, praising the song's production, as well as Lovato's maturing vocal range, which has been compared to Kelly Clarkson. The singled debuted at number 12 on the Billboard Hot 100. Having sold over 215,000 units in its first week, "Heart Attack" currently holds the third-highest opening-week sales figure of 2013, behind Justin Timberlake's "Suit & Tie" and Ariana Grande's "The Way". Reaching international airplay, "Heart Attack" became a top twenty hit in Canada, New Zealand, Ukraine, and Chile.

Lyrics

Putting my defenses up
Cause I don't wanna fall in love
If I ever did that, I think I'd have a heart attack

Never put my love out on the line
Never said yes to the right guy
Never had trouble getting what I want
 But when it comes to you I'm never good enough

When I don't care
I can play him like a Ken doll
Won't wash my hair
Then make him bounce like a basketball

But you make me wanna act like a girl
Paint my nails and wear high heels
Yes you, make me so nervous that I just can't hold your hand

You make me glow
But I cover up, won't let it show
So I'm putting my defenses up
Cause I don't wanna fall in love

If I ever did that, I think I'd have a heart attack
I think I'd have a heart attack
I think I'd have a heart attack

Never break a sweat for the other guys
When you come around I get paralyzed
And every time I try to be myself
It comes out wrong like a cry for help

It's just not fair
Brings more trouble than it all is worth
I gasp for air
It feels so good, but you know it hurts

But you make me wanna act like a girl
Paint my nails and wear perfume
For you, make me so nervous that I just can't hold your hand

You make me glow
But I cover up, won't let it show
So I'm putting my defenses up
Cause I don't wanna fall in love
If I ever did that, I think I'd have a heart attack
I think I'd have a heart attack
I think I'd have a heart attack

The feelings got lost in my lungs
They're burning, I'd rather be numb
And there's no one else to blame
So scared I'll take off and run
I'm flying too close to the sun
And I'll burst into flames

You make me glow
But I cover up, won't let it show
So I'm putting my defenses up
Cause I don't wanna fall in love
If I ever did that, I think I'd have a heart attack
I think I'd have a heart attack
I think I'd have a heart attack
I think I'd have a heart attack
I think I'd have a heart attack