What is a heart attack? Myocardial infarction (MI), commonly known as a heart attack, occurs when the blood supply is cut off, causing damage or death of heart cells. A heart attack can be caused by many reasons. You can tell when someone is having a heart attack by the numerous symptoms. A heart attack occurs when an artery that supplies blood to the heart collapses and stops blood flow to the heart. A heart attack is very deadly and can kill you instantly if more than one artery collapses at the same time or if you have had several in the past. “Every year approximately 600,000 people die of a heart attack, 1 in 4 people. Every year approximately 720,000 people have a heart attack (Heart Disease, 2014).” The cause of a heart attack is the blockage of an artery, for an artery to become blocked it will have a buildup of substances such as cholesterol. "Some common symptoms of a heart attack are: pressure, tightness, pain or tightness sensation in the chest or arms that may spread to the neck, jaw or back, nausea, indigestion, heartburn or abdominal pain, shortness of breath, Freddo ...