Myoglobin level peaks at five times the normal level at around 12 hours after the initial infarction. It then decreases over 12 hours to the normal level. At 24 hours after the initial infarction, the Troponin T will be at 15 times the normal level. The CK-MB will be downtrending but still around 4 times the normal level. Cardiac enzymes do not remain at the same level for a long period after the initial infarction; they either increase or decrease.