Heart Attack

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

Definition

A heart attack is due to a blockage of blood flow to an area of the heart. The heart tissue becomes damaged or dies within a short time after blood flow is stopped. If a large or vital area is affected the damage may stop the heart.

Heart Attack

Heart Attack
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Causes    TOP

The coronary arteries bring blood and oxygen to the heart muscle. A heart attacks occurs when one or more of these arteries is blocked. Blockage may occur because of one or more of the following:

  • Narrowing of the coronary arteries due to:
    • Thickening of the artery walls (common aging process)
    • Build up of fatty plaques inside the arteries
    • Spasm of the coronary arteries
    • Development of a blood clot in the arteries
  • Embolism—a blood clot that travels to the heart from other areas of the body

There are two main coronary arteries. They split off into smaller branches that spread out over the heart. The severity of the heart attack will depend on where the blockage happens:

  • Blockage in the larger arteries—affects a larger area of the heart
  • Blockage in the smaller vessels—affects a smaller area of the heart

Blockages may only last a short time and then allow some blood flow. Others may last longer, and lead to more damage.

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 usually comes on quickly especially with:
    • Exercise or exertion
    • Emotional stress
    • Cold weather
    • A large meal
  • Pain in the left shoulder, left arm, or jaw
  • Shortness of breath
  • Sweating, clammy skin
  • Nausea
  • Weakness
  • Loss of consciousness
  • Anxiety, especially feeling a sense of doom or panic without apparent reason

Unusual symptoms of heart attack—more common in women:

  • Stomach pain
  • Back and shoulder pain
  • Confusion
  • 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—shows the electrical activity of the heart. It can show if a heart attack has happened or may be happening. It can also help determine if the heart attack is:
    • STEMI—A major coronary artery is fully blocked. This is a more serious type of heart attack
    • NSTEMI—It is a partial block of an artery. The block may also allow periods of some blood flow.
  • Blood tests—can show markers in the blood. These markers appear when a heart attack and can show how much damage was done.
  • Echocardiogram—creates images of the size, shape, function, and motion of the heart.
  • Coronary angiography—used to look at coronary arteries. Can help find blockages or damage to the arteries.

Other test will be based on your specific needs but may include:

  • Stress test—Records the heart's electrical activity under physical stress. May be done days or weeks after the heart attack.
  • Electron-beam computed tomography (EBCT)—Takes images of the heart, coronary arteries, and surrounding area.

Treatment    TOP

The first goal of treatment is to improve blood flow and get oxygen to your heart as quick as possible. Treatment includes:

  • Aspirin and other antiplatelet agents—to decrease clotting in the blood and improve blood flow.
  • Oxygen therapy—to increase the amount of oxygen in the blood. This will increase oxygen that is available to the heart.
  • Nitrate medications—to help the blood vessels open. It can improve blood flow.
  • Blood thinners –to thin the blood and help to dissolve blood clots. Includes aspirin, aspirin-like medications, and anticoagulants.
  • Pain-relieving medication
  • Beta-blockers and/or angiotensin-converting enzyme (ACE) inhibitor medications—to decrease the workload on the heart.
  • Anti-anxiety medicine
  • Cholesterol-lowering medications such as statin drugs—may decrease chance of another heart attack or stroke.

Removing Blockages

Medicine may be given to try to break up blood clots. The sooner these medicines are given the better the outcome will be. It works best when given within the first 6 hours after symptoms appear.

Surgery may be needed for:

  • Clots that do not respond to medicine
  • Blockages caused by plaque buildup

Severe blockages may need to be treated right away. Surgery may be delayed for a few days if there is enough blood flow to the heart. Surgical options include:

  • Balloon angioplasty—A wire is passed through blood vessels to the heart. A balloon is used to open the blocked artery. A stent may also be placed. It will help keep the area open.
  • Coronary artery bypass grafting (CABG)—An open surgery. A part of a blood vessel from another area of the body will be taken. It is used to make a path around the blocked area in the heart.

Recovery

Cardiac rehabilitation can help after a heart attack. It may include:

  • Monitoring during physical activity in the first few weeks of recovery
  • Education on healthful nutrition and lifestyle changes

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

Prevention    TOP

Many lifestyle habits influence the health of the blood vessels and heart. Healthy heart habits include:

Small daily doses of aspirin may help some people decrease their risk. This should only be done with your doctor’s approval. Aspirin can have side effects like bleeding in the stomach. Aspirin may also cause problems with other medicine.

RESOURCES:

American Heart Association
http://www.heart.org
National Stroke Association
http://www.stroke.org

CANADIAN RESOURCES

Heart and Stroke Foundation of Canada
http://www.heartandstroke.ca
The College of Family Physicians of Canada
http://www.cfpc.ca

References:

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: https://www.nhlbi.nih.gov/health/health-topics/topics/heartattack. 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 http://www.dynamed.com/topics/dmp~AN~T233244/Testosterone: 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 May 2018 by EBSCO Medical Review BoardMichael J. Fucci, DO, FACC
Last Updated: 5/24/2018

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