Multiple methods. Myocardial infarction (mi) is suspected by symptoms usually including chest pain. The conclusive diagnosis is established based on a combination of specific abnormalities of the electrocardiogram (ekg) and presence of certain heart enzymes that leak into the blood during an mi. The most common enzymes are called ck-mb and troponin.
EKG and blood. The diagnosis of acute mi is based on evolutionary changes on the ekg and a characteristic rise and fall of the cardiac troponin enzymes. A scar (or old mi) can be suspected from an abnormal ekg, wall motion abnormality on echo, or a fixed perfusion defect on nuclear testing.