It's so common for young healthy people to have heart problems these days. Luckily she's ok and will make a full recovery.
Just over 2 years ago my best mate was out on a run when his heart packed in, he died there and then, he was 21. It's so horrible and it's something I don't think I'll ever get over. When it happened and I started looking up about it you realise how common it is.
:(