Rates of MI for a given age have decreased globally between 1990 and 2010. In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $11.5 billion for 612,000 hospital stays. Terminology
Myocardial infarction (MI) refers to tissue death (infarction) of the heart muscle (myocardium) caused by ischaemia, the lack of oxygen delivery to myocardial tissue. It is a type of acute coronary syndrome, which describes a sudden or short-term change in symptoms related to blood flow to the heart. Unlike the other type of acute coronary syndrome, unstable angina, a myocardial infarction occurs when there is cell death, which can be estimated by measuring by a blood test for biomarkers (the cardiac protein troponin). When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG.The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause—cardiac arrest, where the heart is not contracting at all or so poorly that all vital organs cease to function, thus might lead to death. It is also distinct from heart failure, in which the pumping action of the heart is impaired. However, an MI may lead to heart failure. Signs and symptoms
Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction.
It might be accompanied by other symptoms such as sweating. Pain
Chest pain is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen. The pain most suggestive of an acute MI, with the highest likelihood ratio, is pain radiating to the right arm and shoulder. Similarly, chest pain similar to a previous heart attack is also suggestive. The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes. It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether. Levines sign, in which a person localizes the chest pain by clenching one or both fists over their sternum, has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value.Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of nitroglycerin, but nitroglycerin may also relieve chest pain arising from non-cardiac causes. Other
Chest pain may be accompanied by sweating, nausea or vomiting, and fainting, and these symptoms may also occur without any pain at all. In women, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue.