Heartbreak isn't the only thing Miley Cyrus is confessing in her new book: Miley, Miles to Go.
The tween queen reveals that she's suffering from a heart condition called tachycardia that often leaves her worrying for her health.
The condition causes her heart rate to exceed the range of a normal resting heart rate, so you can only imagine how worried she is when she's on stage putting on a full performance.
She writes, "The type of tachycardia I have isn’t dangerous. It won’t hurt me, but it does bother me. There is never a time onstage when I’m not thinking about my heart."
The important thing is that her condition isn't life threatening, but it's still something no one wants to deal with.