Many laboratory aids are now available to help in the diagnosis of coronary artery disease. The electrocardiogram can show the difference between coronary insufficiency, sometimes considered as a small coronary occlusion, and the large coronary occlusion. The former is often preventable and has a favorable prognosis. Coronary occlusion has no specific treatment. Other tests such as determination of muscle enzymes in the blood, the vectorcardiogram, and roentgenography are also available to assist in determining the specific clinical diagnosis.