Demi Lovato: 'Heart Attack' Full Song - LISTEN NOW!

Demi Lovatos brand new single Heart Attack has officially premiered online!

The 20-year-old singer was originally set to premiere the song on March 4th, but joined forces with Ryan Seacrest to surprise fans and post it tonight!

PHOTOS: Check out the latest pics of Demi Lovato

Surprise! Were premiering @ddlovatos new song #HeartAttack TONIGHT!! Go listen now, Ryan wrote on his Twitter account, linking to the On Air with Ryan Seacrest site.

Unfortunately, On Airs site crashed almost immediately from all of the Lovatics trying to listen!

WHAT DO YOU THINK of Demis new single??

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