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Heart Attack

(Acute Myocardial Infarction [AMI]; Myocardial Infarction [MI]; ST-Segment-Elevation MI [STEMI]; Transmural Myocardial infarction)


A heart attack is when blood flow to part of the heart is blocked. The heart tissue gets hurt or dies within a short time after blood flow stops. It may stop working if a large or vital part of the heart is involved.

Heart Attack

Heart Attack
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Causes    TOP

Coronary arteries are arteries that supply oxygen-rich blood to the heart. A heart attack is when blood flow is blocked in them. This may be from:

  • Narrowing of the arteries from:
    • Thickening due to aging
    • Build up of fatty plaques
    • Spasms
    • Blood clots
  • A clot that travels to the heart and blocks off smaller coronary arteries

The amount of tissue that is harmed will depend on which artery is blocked. There are 2 main arteries that split into smaller branches. If a large artery is blocked, it harms a larger part of the heart. If a small vessel is blocked, it harms a smaller part of the heart.

Risk Factors    TOP

The risk of heart attack is greater in males and older adults.

You have a higher risk of a heart attack if you do not have healthy blood vessels. This may be due to:

Symptoms    TOP

Symptoms can differ from person to person. Common ones are:

  • Squeezing, heavy chest pain behind breastbone that starts quickly with:
    • Activity or strain
    • Stress
    • Cold weather
    • A large meal
  • Pain in the left shoulder, left arm, or jaw
  • Problems breathing
  • Sweating, clammy skin
  • Nausea
  • Lack of energy
  • Loss of consciousness
  • Panic attacks

Signs of a heart attack may happen more often in women. The signs are not as common:

  • Stomach pain
  • Back and shoulder pain
  • Appearing confused
  • Fainting

Call for emergency services right away if you think you may be having a heart attack. Early care can stop further damage.

Diagnosis    TOP

If the doctor suspects a heart attack it may be confirmed with:

  • ECG—Records electricity in the heart. It can show if you had a heart attack or if you will have one. It can also find out if the heart attack is:
    • STEMI—A total block of an artery. This is a more serious type of heart attack
    • NSTEMI—A partial block of an artery. Some blood may still be able to flow.
  • Blood tests—Certain markers in the blood will appear or rise if a heart attack has occurred. These markers can also show how much harm was done to the heart muscle.
  • Echocardiogram—A test to look at the size, shape, and motion of the heart as well as how it is working
  • Coronary angiography—A wire is passed through vessels to look for any blocked or harmed arteries

More testing may be done to look for any harm or changes to the heart. Tests will be based on your needs. You may have a:

  • Stress test—Records electricity in the heart under physical stress. This can be done days or weeks after the heart attack
  • Electron-beam computed tomography (EBCT)—Takes in depth pictures of the heart, arteries, and other structures

Treatment    TOP

The first goal is to get blood to flow and get oxygen to your heart quickly. You may have:

  • Aspirin and other blood thinning medicines—Will thin the blood to help it flow smoother
  • Oxygen—Breathing more oxygen will raise the amount of oxygen in the blood for the heart
  • Nitrates—Can help the vessels open up to allow better blood flow
  • Pain-relievers
  • Beta-blockers and angiotensin-converting enzyme (ACE) inhibitors—To lower the workload on the heart
  • Anti-anxiety medicine
  • Cholesterol-lowering medications such as statins—May play a vital role in lowering the chance of more heart attacks or a stroke

Removing Blockages

If you have a blood clot, medicines may be given to try to break it up. The sooner they are given, the better the result. It is best if they are given within the first 6 hours after you have signs of a heart attack.

Surgery may be needed for blood clots that don’t get better with medicine or plaque build up. It may need to be done right away for large blockages or delayed for a few days if there is enough blood flow. The surgeries are:

  • Balloon angioplasty—A wire is passed through blood vessels and a balloon is used to open up the blocked artery. A stent may also be placed in the blood vessel to help keep it open.
  • Coronary artery bypass grafting (CABG)—An open surgery that uses a section of blood vessel from somewhere else in the body to make a path around the blocked part.


Cardiac rehabilitation can help you get better after a heart attack. You may be monitored during physical activity in the first few weeks. You may also be taught about diet and lifestyle changes.

A heart attack can be a major life event. It is common for people to have depression after having a heart attack. Therapy and medicine can help.

Prevention    TOP

Your habits play a role in the health of the blood vessels and heart. Here are some healthy heart habits:

Small daily doses of aspirin may help some people lower their risk of heart attack. You should only use aspirin in this way if your doctor says it is okay. Aspirin can cause problems like bleeding in the stomach or intestines. It may also cause problems with other medicines.


American Heart Association
National Stroke Association


Heart and Stroke Foundation of Canada
The College of Family Physicians of Canada


About heart attacks. American Heart Association website. Available at:
...(Click grey area to select URL)
Updated January 27, 2017. Accessed September 12, 2017.
Antithrombotic Trialists' (ATT) Collaboration, Baigent C, Blackwell L, et al. Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials. Lancet. 2009;373:1849-1860.
Explore heart attack. National Heart Lung and Blood Institute website. Available at: Updated January 27, 2015. Accessed September 29, 2014.
ST-elevation myocardial infarction (STEMI). EBSCO DynaMed Plus website. Available at: http://www.dynamed.... Updated June 12, 2017. Accessed September 12, 2017.
2/3/2014 DynaMed Plus Systematic Literature Surveillance Finkle W, Greenland S, Ridgeway GK, et al. Increased risk of non-fatal myocardial infarction following testosterone therapy prescription in men. PLoS One. 2014;9(1):e85805.
7/17/2017 DynaMed Plus Systematic Literature Surveillance http://www.dynamed...: Bally M, Dendukuri N, Rich B, et al. Risk of acute myocardial infarction with NSAIDs in real world use: bayesian meta-analysis of individual patient data. BMJ. 2017;357:j1909.
Last reviewed September 2017 by EBSCO Medical Review BoardMichael J. Fucci, DO, FACC
Last Updated: 5/24/2018

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