The Causes of a Heart Attack A heart attack is usually preceded by arteriosclerosis of the coronary vessel (coronary heart disease). This narrows, to a greater or lesser extent, the coronary vessels by depositing fatty, partly calcified substances – the so-called plaque – on the vessel walls. This coronary-artery sclerosis develops mainly in that various harmful influences (e.g. high blood pressure, smoking, sugar, fat) act on the sensitive internal lining membrane (endothelium) of the blood vessels. This damage enables the blood lipid LDL cholesterol to penetrate the endothelium in the internal walls of the blood vessel. There, the LDL particles can cause inflammation. When the inflammatory reaction heals, it leaves scars on the connective tissue and calcification, the plaque. The wall of the blood vessel becomes thicker and begins to narrow the vessel. New outbreaks of inflammation in the plaque, however, can cause the inner side of the blood vessel to suddenly tear. The tear is instantly sealed by blood platelets. The blood clot (coagulum or thrombus) can become so large that the blood vessel at this point is fully blocked and the result is an acute heart attack. Other causes for blockage of a coronary vessel are very rare and are therefore not taken into consideration here. top