The CK-MB test is a critical, time-sensitive diagnostic for heart health. It measures the level of CK-MB, a specific enzyme found almost exclusively in your heart muscle. When the heart muscle is damaged, such as during a heart attack, it releases CK-MB into the bloodstream. This test is therefore essential in an emergency setting to help doctors diagnose a myocardial infarction quickly and accurately. This test, requiring a simple blood draw, provides the rapid, life-saving information your doctor needs to protect your heart during a critical event.