CK Creatine Kinase and Troponin are some of the enzymes that indicate a attack

C-Reactive Protein may also used to detect a heart attack.

Blood test are used in conjunction with a electrocardiogram (EKG, ECG), so the doctors can offer the best treatment when dealing with someone they suspect as having a heart attack.

I am not sure of the normal levels but I have included a few links which may give you the levels.