Heart attack and cholesterol. Illustration of myo- cardial infarction (heart attack) due to a blood clot (thrombus) in the coronary artery. At right, a high cholesterol diet has resulted in deposits of fat (yellow) forming around coronary blood vessels of the heart. A blood clot has developed in the left coronary artery (partly dissected) and tissue death of the cardiac muscle has occurred. At left, the coronary artery is seen magnified and cut through. The lumen of the artery has narrowed due to cholesterol accumulation (yellow) within the artery wall. A blood clot has formed. Blood squeezing through a narrow artery encourages clot formation, often with fatal consequences.