The title track "Heart Attack" required a few listen from me before I really started to appreciate the song, as well as Chuu (Kim Ji Woo) herself. The song gave off a quirky, jazz sound that will pull you into it especially after a few more listen. I won't even hesitate to say that "Heart Attack" is one of the best track among their solo pre-debut tracks. It also showed off Chuu's impressive vocal.
"Girl's Talk" in the other hand offers a dreamy, EDM sound, which is quite different from the title track. It doesn't sound as good as the others' B-Side, because for me, it doesn't really grab my attention (even after a few listens).