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Heart attack - Overview

Alternative Names

Myocardial infarction; MI; Acute MI; ST-elevation myocardial infarction; non-ST-elevation myocardial infarction

Definition of Heart attack:

A heart attack is when blood vessels that supply blood to the heart are blocked, preventing enough oxygen from getting to the heart. The heart muscle dies or becomes permanently damaged. Your doctor calls this a myocardial infarction.

Causes, incidence, and risk factors:

Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart starves for oxygen and heart cells die.

In atherosclerosis, plaque builds up in the walls of your coronary arteries. This plaque is made up of cholesterol and other cells. A heart attack can occur as a result of the following:

The slow buildup of plaque may almost block one of your coronary arteries. A heart attack may occur if not enough oxygen-containing blood can flow through this blockage. This is more likely to happen when you are exercising.
The plaque itself develops cracks (fissures) or tears. Blood platelets stick to these tears and form a blood clot (thrombus). A heart attack can occur if this blood clot completely blocks the passage of oxygen-rich blood to the heart.

Occasionally, sudden overwhelming stress can trigger a heart attack.

Risk factors for heart attack and coronary artery disease include:

Increasing age (over age 65)
Male gender
Diabetes
Family history of coronary artery disease (genetic or hereditary factors)
High blood pressure
Smoking
Too much fat in your diet
Unhealthy cholesterol levels, especially high LDL ("bad") cholesterol and low HDL ("good") cholesterol
Chronic kidney disease

Heart, section through the middle

Heart, front view

Acute MI

Post myocardial infarction ECG wave tracings

Progressive build-up of plaque in coronary artery

Posterior heart arteries

Anterior heart arteries

Heart attack symptoms

Reviewed last on: 4/23/2009
Alan Berger, MD, Assistant Professor, Divisions of Cardiology and Epidemiology, University of Minnesota, Minneapolis, MN. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Anderson JL, Adams CD, Antman EM, Bridges CR, Califf RM, Casey DE Jr., et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine. J Am coll Cardiol. 2007;50:e1-e157.

King SB 3rd, Smith SC Jr., Hirschfeld JW Jr., Jacobs AK, Morrison DA, Williams DO, et al. 2007 Focused Update of the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines: 2007 Writing Group to Review New Evidence and Update the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention. Writing on Behalf of the 2005 Writing Committee. Circulation. 2008;117:261-295.

Antman Em. ST-Elevation myocardial infarction: managemtn. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsever; 2007:chap 51.

Goodman SG, Menon V, Cannon CP, Steg G, Ohman EM, Harrington RA, et al. Acute ST-segment elevation myocardial infarction: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th edition). Chest. 2008;133:708S-775S.

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