Heart Attack

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

by Rosalyn Carson-DeWitt, MD

Understanding Arterial Plaque

Definition

A heart attack occurs when blood flow to the heart muscle is interrupted. Oxygen can't get to the heart muscle, causing tissue damage or tissue death.

Heart Attack

© 2009 Nucleus Medical Media, Inc.

Causes

A heart attack may be caused by:

• Thickening of the walls of the arteries feeding the heart muscle (coronary arteries)
• Accumulation of fatty plaques in the coronary arteries
• Narrowing of the coronary arteries
• Spasm of the coronary arteries
• Development of a blood clot in the coronary arteries

Risk Factors

These factors increase your chance of developing heart attack. Tell your doctor if you have any of these:

• Sex: male
• Increased age
• Obesity
• Smoking
• High blood pressure
• Sedentary lifestyle
• High blood cholesterol (specifically, high LDL cholesterol, and low HDL cholesterol)
• High blood triglycerides
• Diabetes
• Stress
• Family members with heart disease

Symptoms

Symptoms include:

• Squeezing, heavy chest pain, 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 (may occur more frequently in women):

• Stomach pain
• Back and shoulder pain
• Confusion
• Fainting

Diagnosis

If you think you are having a heart attack, call 911 right away.

Tests may include:

• Blood tests—to look for certain enzymes found in the blood within hours or days after a heart attack
• Urine tests—to look for certain substances found in the urine within hours or days after a heart attack
• Electrocardiogram (EKG) —records the heart's activity by measuring electrical currents through the heart muscle, changes can show if there is blockage or damage
• Echocardiogram —uses high-frequency sound waves (ultrasound) to examine the size, shape, function, and motion of the heart
• Stress test —records the heart's electrical activity under increased physical stress, usually done days or weeks after the heart attack
• Nuclear scanning—uses radioactive material to show areas of the heart muscle where there is diminished blood flow
• Electron-beam computed tomography (EBCT) —a type of x-ray that uses a computer to make detailed pictures of the heart, coronary arteries, and surrounding structures; may be helpful if you are at immediate risk of coronary artery disease
• Coronary angiography —uses dye and x-rays to look for narrowing or blockage in the coronary arteries

Treatment

Treatment includes:

• Oxygen
• Pain-relief medications (such as morphine)
• Nitrate medications
• Aspirin and other antiplatelet agents
• Beta-blocking and/or ACE inhibitor medications (frequently given)
• Anti-anxiety medications
• Clot-dissolving agents (thrombolytics)—Within the first six hours after a heart attack, you may be given medications to break up blood clots in the coronary arteries.
  • Other medicines that may be given include those that block the function of platelets (called platelet IIb/IIIa receptor blockers).
• Cholesterol-lowering medications (eg, statin drugs)

Prevention

Preventing or treating coronary artery disease may help prevent a heart attack.

• Maintain a healthy weight.
• Begin a safe exercise program. Follow your doctor's advice.
• If you smoke, quit.
• Eat a healthful diet. Your diet should be low in saturated fat and rich in whole grains, fruits, and vegetables.
• Treat high blood pressure, diabetes and high cholestrol.
• Manage stress.
• Ask your doctor about taking a small, daily dose of aspirin.
  • Although most people are able to tolerate such a low dose of aspirin, even this small amount can rarely lead to serious bleeding, particuarly from the gastrointestinal (GI) tract .
  • Aspirin may not work as well when combined with other pain medications.

American Heart Association
http://www.americanheart.org/

Heart and Stroke Foundation
http://www.heartandstroke.com/

Heart Healthy Kit: Public Health Agency of Canada
http://www.phac-aspc.gc.ca/

Heart and Stroke Foundation
http://ww2.heartandstroke.ca/

REFERENCES:

Heart attack. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/heart-attack/DS00094/DSECTION=8 . Updated 2007. Accessed June 29, 2008.

Meier MA, Al-Badr WH, Cooper JV, et al. The new definition of myocardial infarction: diagnostic and prognostic implications in patients with acute coronary syndromes. Arch Intern Med . 2002;162:1585-1589.

Mollet NR, Cademartiri F, van Mieghem CA, et al. High-resolution spiral computed tomography coronary angiography in patients referred for diagnostic conventional coronary angiography. Circulation . 2005;112:2318-2323. Epub 2005 Oct 3.

Rakel RE, Bope ET. Conn's Current Therapy 2001 . 53rd ed. Philadelphia, PA: WB Saunders Company; 2001.

What is a heart attack? American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=3007482 . Accessed June 29, 2008.

Women Physicians Congress. What you need to know about heart disease. American Medical Association website. Available at: http://www.ama-assn.org/ . Updated 2008. Accessed June 29, 2008.

¹11/7/2007 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Bravata DM, Gienger AL, McDonald KM, et al. Systematic Review: The comparative effectiveness of percutaneous coronary interventions and coronary artery bypass graft surgery. Ann Intern Med. 2007 Nov 20. [Epub ahead of print]

²7/6/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : 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.

Last reviewed September 2009 by David N. Smith, MD
Last Updated: 9/30/09