Coxsakie is a virus. An infection can cause various symptoms - cold like, Hand, foot and mouth disease, etc. and like any viral infection can cause some complications, cardiac among them. So if your daughter did have a Coxsackie virus infection and has some suspected heart problems it is a good thing to have pediatric cardiologist see her. You didn't write what symptoms she has so it's hard to say more, but try to stay calm until the cardiologist sees her. It doesn't have to be serious. It might be just to check to be on the safe side. She might just need some rest.
Good luck - I hope everything will be just fine.