Heart Attack

Heart Attack

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

Definition

A heart attack is when an area of the heart does not get enough blood flow. The area becomes damaged or dies within a short time after blood flow is stopped. If a large or vital area is affected the heart may stop. A heat attack may be:

  • STEMI—A major artery is fully blocked. This is a more serious type of heart attack
  • NSTEMI—Partial block of an artery. The block may also allow periods of some blood flow.

Heart Attack

Heart Attack
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Causes

The coronary arteries bring blood and oxygen to the heart muscle. A heart attack 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 one or more of following:
    • 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 2 main coronary arteries. They split off into smaller branches that spread out over the heart. A blockage on larger artery will affect more of the heart. It can cause a severe heart attack. Blockages in the smaller arteries will have a smaller effect.

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

Risk Factors

The risk of heart attack is greater in males and older adults. The risk of a heart attack is also higher in those with blood vessel disease or damage. Things that may increase risk of blood vessel disease and heart attacks are:

Symptoms

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

A heart attack is an emergency. Tests to confirm a heart attack and look for changes in the heart include:

  • ECG—shows the electrical activity of the heart. It can show if a heart attack has happened or may be happening. ECG can show if the heart attack is STEMI or NSTEMI.
  • Blood tests—can show markers in the blood. These markers appear when a heart attack occurs. They can also show how much damage was done to the heart muscle.
  • Echocardiogram—shows the size, shape, and motion of the heart.
  • Coronary angiography—Can help find blockages or damage to the arteries.

Other tests 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

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

  • Aspirin and other antiplatelet agents—to break up clots in the blood and improve blood flow. It works best when given within the first 6 hours after symptoms appear.
  • Oxygen therapy—to increase oxygen to the heart.
  • Nitrate medications—to quickly open blood vessels and improve blood flow to heart muscle.
  • Pain-relieving medicine
  • Beta-blockers and/or angiotensin-converting enzyme (ACE) inhibitors—to decrease the workload on the heart.
  • Anti-anxiety medicine

Surgery

Surgery may be needed for clots that do not respond to medicine. Some blockages may also be caused by a buildup of plaque in blood vessels. Surgery can help to improve blood flow. Surgical options include:

  • Balloon angioplasty—A wire is passed through blood vessels to the heart. A balloon is inflated to press open the blocked artery. A mesh device called a stent may also be placed. It will help prop the area open.
  • Coronary artery bypass grafting (CABG)—Part of a blood vessel from another area of the body will be taken. It will be attached above and below the blocked area to create blood flow around the blockage.

Recovery

Cardiac rehabilitation can help after a heart attack. It will teach healthy habits to decrease the risk of another heart attack. The program will also monitor the heart as physical activity is increased. Severe heart attacks can also make the heart weaker. Rehabilitation can help to adjust to 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

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)
Accessed September 14, 2020.
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. Accessed September 14, 2020.
ST-elevation myocardial infarction (STEMI). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/st-elevation-myocardial-infarction-stemi. Accessed September 14, 2020.
2/3/2014 DynaMed Systematic Literature Surveillance
...(Click grey area to select URL)
Finkle W, Greenland S, 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 Systematic Literature Surveillance https://www.dynamed.com/condition/acute-coronary-syndromes: Bally M, Dendukuri N, 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 2020 by EBSCO Medical Review Board Michael J. Fucci, DO, FACC
Last Updated: 9/15/2020

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