What is a myocardial infarction or heart attack ?br It is a life threatening emergency. It presents itself when, following the rupture of an atherosclerotic plaque, a blood clot occludes a coronary artery. The obstruction of the artery prevents blood form providing oxygen to the concerned region of the heart. As a consequence, this cardiac region loses the ability to contract and pump blood. Without an immediate intervention, it risks being permanently damaged.