ECG / EKG (Electrocardiogram) can detect it even years later. Old myocardial infarctions (heart attack) will manifest as pathological Q waves in the ECG. Cardiac troponin test detects a recent myocardial infarction for about 2 weeks. CPK (Creatine Phosphokinase) can detect it for a few days. The CPK value peaks at about 24 hours after a myocardial infarction. Echocardiogram can also detect an old myocardial infarction for a long period. Nuclear imaging and MRI (Magnetic Resonance Imaging) can also detect previous myocardial infarction. But if these tests are negative, it does not always exclude a previous heart attack, as the evidence may not persist long in mild attacks.
