"It was the first thing Harry did, as soon as we knew how far-ranging the curse's effects were. He found a hole in Hermione’s heart ... and it was growing. He thinks that the curse was only in an experimental stage when it was used on Hermione as a youngster. It wasn't as potent as this version. Even so, if Harry hadn't found it and repaired it when he did, Hermione might have been dead within a year."