Myocardial Infarction

Myocardial infarction (MI; Latin: infarctus myocardii) or acute myocardial infarction (AMI), commonly known as a heart attack, occurs when blood stops flowing properly to a part of the heart, and the heart muscle is injured because it is not receiving enough oxygen. Usually, this is because one of the coronary arteries that supplies blood to the heart develops a blockage due to an unstable buildup of white blood cells, cholesterol and fat. The event is called "acute" if it is sudden and serious. Myocardial infarction differs from cardiac arrest, although cardiac arrest can be a consequence of MI.

A person having an acute MI usually has sudden chest pain that is felt behind the sternum and sometimes travels to the left arm or the left side of the neck. Additionally, the person may have shortness of breath, sweating, nausea, vomiting, abnormal heartbeats, and anxiety. Women experience fewer of these symptoms than men, but usually have shortness of breath, weakness, a feeling of indigestion, and fatigue. In many cases, in some estimates as high as 64%, the person does not have chest pain or has vague symptoms. These are called "silent" myocardial infarctions.

Important risks are previous cardiovascular disease, old age, tobacco smoking, abnormal blood levels of certain lipids, diabetes, high blood pressure, lack of physical activity, obesity, chronic kidney disease, excessive alcohol consumption, and the use of cocaine and amphetamines. The main ways to determine if a person has had a myocardial infarction are electrocardiograms (ECGs) that trace the electrical signals in the heart and testing the blood for substances associated with damage to the heart muscle. ECG testing is used to differentiate between two types of myocardial infarction based on the appearance of the tracing. An ST section of the tracing higher than the baseline is called an ST elevation MI (STEMI) which usually requires more aggressive treatment. If this is not the case, the diagnosis is confirmed with a blood test (usually troponin).

Immediate treatments for a suspected MI often include aspirin, which prevents further blood from clotting; nitroglycerin, sometimes given to treat chest pain; and oxygen. STEMI is treated by restoring circulation to the heart, called reperfusion therapy, and typical methods are angioplasty, where the arteries are pushed open, and thrombolysis, where the blockage is removed using medications. Non-ST elevation myocardial infarction (NSTEMI) may be managed with medication, although angioplasty may be required if the person is considered to be at high risk. who have multiple blockages of their coronary arteries, particularly if they also have diabetes, may also be treated with bypass surgery (CABG).Ischemic heart disease, which includes MI, angina, and heart failure when it happens after MI, was the leading cause of death for both men and women worldwide in 2011