Coronary thrombosis. Light micrograph of a section through a thrombus (blood clot) in the coronary artery of the heart. The clot is packed full of red blood cells (red) and monocytes (a type of white blood cell, purple), along with platelets (thrombocytes) with the clotting protein fibrin (pink). Coronary clots can prevent oxygen- carrying blood from reaching parts of the heart muscle. If the blood supply to a part of the heart is interrupted, it can result in a heart attack, technically known as an acute myocardial infarction (AMI). This damages the heart and is potentially fatal. Thrombi (clots) may also block arteries supplying the brain, legs, kidneys, and other areas of the body.