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# Myocardial Infarction

my·o·car·di·al in·farc·tion - my-oh-KAR-dee-ul in-FARK-shun

## Definition

A myocardial infarction - commonly known as a heart attack - occurs when blood flow to a section of heart muscle is blocked for long enough that the muscle tissue begins to die. The blockage is almost always caused by a blood clot that forms when an atherosclerotic plaque in a coronary artery ruptures, suddenly obstructing the vessel.

The heart muscle requires a constant supply of oxygen-rich blood to function. When a coronary artery is blocked, the portion of heart muscle it supplies is starved of oxygen (a state called ischemia). If blood flow is not restored quickly - typically within minutes to hours - the affected heart tissue sustains permanent damage or dies. The extent of damage depends on which artery is blocked, how much muscle it supplies, and how quickly treatment is received.

Heart attacks are medical emergencies. The classic symptoms include chest pain or pressure (often described as a squeezing, heaviness, or tightness), pain radiating to the left arm, jaw, back, or stomach, shortness of breath, cold sweats, nausea, and lightheadedness. However, symptoms can vary significantly - particularly in women, who are more likely to experience atypical symptoms like unusual fatigue, nausea, and back or jaw pain without the classic chest pressure.

## Also Known As

Heart attack MI Acute MI 

## Key Facts

-   • Approximately 805,000 Americans have a heart attack each year - about one every 40 seconds. 
-   • Time is critical: every minute without blood flow means more heart muscle damage. 
-   • The acronym STEMI refers to the most severe type of heart attack, requiring emergency intervention. 
-   • Modern treatments (angioplasty, stents, clot-busting drugs) have dramatically improved survival rates. 
-   • About 1 in 5 heart attacks are "silent" - they occur without the person recognizing what happened. 
-   • After a heart attack, cardiac rehabilitation significantly improves long-term outcomes and quality of life. 

## How It Relates To Your Health

Knowing the warning signs of a heart attack could save your life or the life of someone you love. If you or anyone experiences symptoms suggestive of a heart attack, call emergency services immediately - do not drive yourself to the hospital. Modern treatments can restore blood flow and minimize heart damage, but they are most effective when administered within the first 1-2 hours of symptom onset.

After a heart attack, cardiac rehabilitation - a supervised program of exercise, education, and counseling - is one of the most effective interventions for reducing the risk of a second event and improving quality of life. Unfortunately, fewer than a third of eligible patients participate in cardiac rehab.

## Related Terms

[Atherosclerosis](/glossary/atherosclerosis)[Cholesterol](/glossary/cholesterol)[Hypertension](/glossary/hypertension)[Ejection Fraction](/glossary/ejection-fraction)

## Related Conditions

[

### Atherosclerosis

Cardiovascular 

Atherosclerosis occurs when fatty deposits called plaques build up inside artery walls, narrowing the vessels and restricting blood flow. Over time, this can lead to heart attacks, strokes, or peripheral artery disease depending on which arteries are affected.

Chest pain or angina Leg pain when walking Shortness of breath 

Chronic Learn More 

](/conditions/atherosclerosis)

## Sources

1.  [Heart Attack](https://www.nhlbi.nih.gov/health/heart-attack) - National Heart, Lung, and Blood Institute (NIH)
2.  [Heart Attack Symptoms, Risk, and Recovery](https://www.cdc.gov/heart-disease/about/heart-attack.html) - Centers for Disease Control and Prevention
3.  [Heart attack](https://www.mayoclinic.org/diseases-conditions/heart-attack/symptoms-causes/syc-20373106) - Mayo Clinic

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