From the many I ve personally witnessed, At first the person becomes uncomfortable, nauseated, tired, and just generally doesn t feel well. Some people have a sense of doom . They feel like someone is squeezing or sitting on their chest, they start to sweat profusely, feel very weak and often can t walk more than a few feet without feeling like they ve run a mile. The pain starts spreading down an arm and into their neck and jaw. Some people get panicky, some deny that there could be anything wrong. If they don t get to a hospital, their hearts are often too damaged to support them, they get weaker and weaker until they lose consciousness and die. Not all heart attacks are like this though. Sudden cardiac death is just what it sounds like, your heart stops, you collapse, end of line. Many people, especially woman, don t have the classic symptoms. They feel tired and just can t seem to get anything done. Often they have nausea and back pain, and get fatigued very fast doing simple things like climbing stairs or even walking. On the ambulance we will give them nitroglycerin to ease the heart s workload, aspirin, and other medications, and put them on a cardiac monitor and record the heart s activity to show the ER doctor. We will have the defibrillator waiting just in case. So sometimes they do just fall down and die, and sometimes it takes a long time, and even with medical help they still die. That s why we tell people not to wait on calling 911.