An EKG is one of several tests that can help diagnose a heart attack. This is often one of the first screenings performed when someone goes to the hospital with heart attack symptoms. Abnormal EKG readings can not only indicate the possibility of heart muscle damage but can also be the result of reduced blood flow through the coronary arteries. This is usually the trigger for most heart attacks. An EKG can also diagnose abnormal heart rhythms called arrhythmias. In addition to an EKG, blood tests are done if a heart attack is suspected. Damaged heart tissue often releases certain proteins called troponins. Abnormally high levels of troponin T and troponin I are often a sign of a heart attack.