A heart attack, also known as a myocardial infarction, is a medical emergency caused by the blockage of an artery that supplies blood to the heart. The most common cause of a heart attack is a condition called coronary artery disease, which is caused by a buildup of plaque in the arteries. The crossword solution for this term is CORONARY, which is an 8-letter word. Coronary refers to the arteries that supply blood to the heart, and it is these arteries that can become blocked and cause a heart attack.