The underlying cause of heart attack is the destruction of heart muscle cells due to a lack of oxygen. If these cells are not supplied with sufficient oxygen by the coronary arteries to meet their metabolic demands, they die.
The medical term for a heart attack is acute myocardial infarction, often abbreviated as AMI or MI. "Acute" means sudden, "myo" refers to muscle, and "cardia" refers to heart. The myocardium[?] is the medical name for the heart muscle. "Infarction" is a medical term describing tissue death (necrosis) caused by an obstruction of blood flow.
A common cause of heart attack is atherosclerosis: a gradual buildup of fat-containing substances (plaque) in the walls of the arteries can erupt and cause a blood clot (thrombus) to form; this thrombus can then cause a sudden clogging of the coronary arteries.
Heart attacks can also occur if the work load of the heart suddenly rises and the necessary oxygen cannot be supplied quickly enough. This is why extreme stress or physical exertion can result in heart attacks.
The classical symptom of a heart attack is chest pain. However it is present only in 65-69% of cases. Pain most characteristic of a heart attack is described as "intense pressure" ("like an elephant sitting on your chest") but can also be a sharp or stabbing pain. The pain may radiate to the left arm, neck or the back and can be slight, moderate, or severe. Some associated symptoms include dizziness, nausea, shortness of breath and diaphoresis[?] (excessive sweating). Heart attacks sometimes occur with atypical pain or in the absence of classical symptoms, particularly in women, who may experience simply chest discomfort, a sensation of uncomfortable chest pressure, cold sweats, nausea, or pain in the arm, back, jaw, or stomach (so called anginal equivalents).
A heart attack is a life-threatening medical emergency which demands immediate activation of the emergency medical services. If you have a heart attack, call for help and take an aspirin (it makes blood clots less likely to form). Find other people who can administer CPR should your heart stop beating. Immediate transport by ambulance to a hospital where advanced cardiac life support is available needs to be arranged.
About 20% of patients die before they reach the hospital; the cause of death is often fibrillation[?].
A heart attack is treated with thrombolytic[?] drugs (such as urokinase, streptokinase, or alteplase (recombinant tissue plasminogen activator)), heparin, and medication to prevent arrhythmia. Immediate or delayed treatment with angioplasty or coronary artery bypass surgery is another option. Following a heart attack, a patient's heart rhythm is closely monitored: antiarrhythmic medication may be needed. Some people at risk for coronary disease are prescribed medication to prevent heart attacks (such as aspirin or Plavix (clodipogrel[?])).
See also Ischaemic heart disease.