Most people who die from a heart attack are killed by ventricular fibrillation. This means the normal electrical signals of the heart are disrupted and replaced by chaotic signals that mean the heart isn’t beating regularly and pumping blood throughout the rest of the body. When this occurs, medical personnel have only a short window of time to get the heart beating regularly again. Brain damage or death can occur after only a few minutes of the brain being deprived of oxygen-rich blood.
If you are able to get to an Emergency Room after having a heart attack, your chance of survival improves significantly. Approximately 90 percent of people who are able to get to an ER promptly survive the episode, since most deaths from heart attack are due to ventricular fibrillation that occurs before they can get medical treatment.