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Alternative Names Return to topMyocardial infarction; MI; Acute MI; ST-elevation myocardial infarction; non-ST-elevation myocardial infarction
Definition Return to top
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 Return to top
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:
Occasionally, sudden overwhelming stress can trigger a heart attack.
Risk factors for heart attack and coronary artery disease include:
Symptoms Return to top
Chest pain is a major symptom of heart attack. You may feel the pain in only one part of your body, or it may move from your chest to your arms, shoulder, neck, teeth, jaw, belly area, or back.
The pain can be severe or mild. It can feel like:
The pain usually lasts longer than 20 minutes. Rest and a medicine called nitroglycerin do not completely relieve the pain of a heart attack. Symptoms may also go away and come back.
Other symptoms of a heart attack include:
Some people (the elderly, people with diabetes, and women) may have little or no chest pain. Or, they may experience unusual symptoms (shortness of breath, fatigue, weakness). A "silent heart attack" is a heart attack with no symptoms.
Exams and Tests Return to top
A heart attack is a medical emergency. If you have symptoms of a heart attack, seek immediate medical help. Call 911 or your local emergency number immediately. DO NOT try to drive yourself to the hospital. DO NOT DELAY, because you are at greatest risk of sudden cardiac death in the early hours of a heart attack.
The health care provider will perform a physical exam and listen to your chest using a stethoscope. The doctor may hear abnormal sounds in your lungs (called crackles), a heart murmur, or other abnormal sounds.
You may have a rapid pulse. Your blood pressure may be normal, high, or low.
Tests to look at your heart include:
Blood tests can help show if you have substances produced by heart tissue damage or a high risk for heart attack. These tests include:
Treatment Return to top
If you had a heart attack, you will need to stay in the hospital, possibly in the intensive care unit (ICU). You will be hooked up to an ECG machine, so the health care team can look at how your heart is beating.
Life-threatening irregular heartbeats (arrhythmias) are the leading cause of death in the first few hours of a heart attack. These arrythmias may be treated with medications or electrical cardioverson/defibrillation.
The health care team will give you oxygen, even if your blood oxygen levels are normal. This is done so that your body tissues have easy access to oxygen and your heart doesn't have to work as hard.
An intravenous line (IV) will be placed into one of your veins. Medicines and fluids pass through this IV. You may need a tube inserted into your bladder (urinary catheter) so that doctors can see how much fluid your body removes.
ANGIOPLASTY AND STENT PLACEMENT
Angioplasty, also called percutaneous coronary intervention (PCI), is the preferred emergency procedure for opening the arteries for some types of heart attacks. It should preferably be performed within 90 minutes of arriving at the hospital and no later than 12 hours after a heart attack.
Angioplasty is a procedure to open narrowed or blocked blood vessels that supply blood to the heart.
A coronary artery stent is a small, metal mesh tube that opens up (expands) inside a coronary artery. A stent is often placed after angioplasty. It helps prevent the artery from closing up again. A drug eluting stent has medicine in it that helps prevent the artery from closing.
THROMBOLYTIC THERAPY (CLOT-BUSTING DRUGS)
Depending on the results of the ECG, certain patients may be given drugs to break up the clot. It is best if these drugs are given within 3 hours of when the patient first felt the chest pain. This is called thrombolytic therapy. The medicine is first given through an IV. Blood thinners taken by mouth may be prescribed later to prevent clots from forming.
Thrombolytic therapy is not appropriate for people who have:
Thrombolytic therapy is extremely dangerous in women who are pregnant or in people who have:
OTHER MEDICINES FOR HEART ATTACKS
Many different medicines are used to treat and prevent heart attacks. Nitroglycerin helps reduce chest pain. You may also receive strong medicines to relieve pain.
Antiplatelet medicines help prevent clots from forming. Aspirin is an antiplatelet drug. Another one is clopidogrel (Plavix). Ask your doctor which of these drugs you should be taking. Always talk to your health care provider before stopping either of these drugs.
Other medications you may receive during or after a heart attack include:
CORONARY ARTERY BYPASS SURGERY
Coronary angiography may reveal severe coronary artery disease in many vessels, or a narrowing of the left main coronary artery (the vessel supplying most of the blood to the heart). In these circumstances, the cardiologist may recommend emergency coronary artery bypass surgery (CABG). This procedure is also called "open heart surgery." The surgeon takes either a vein or artery from another location in your body and uses it to bypass the blocked coronary artery.
Support Groups Return to top
See:Heart disease -- resources
Outlook (Prognosis) Return to top
How well you do after a heart attack depends on the amount and location of damaged tissue. Your outcome is worse if the heart attack caused damage to the signaling system that tells the heart to contract.
About a third of heart attacks are deadly. If you live 2 hours after an attack, you are likely to survive, but you may have complications. Those who do not have complications may fully recover.
Usually a person who has had a heart attack can slowly go back to normal activities, including sexual activity.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Immediately call your local emergency number (such as 911) if you have symptoms of a heart attack.
Prevention Return to top
To prevent a heart attack:
If you have one or more risk factors for heart disease, talk to your doctor about possibly taking aspirin to help prevent a heart attack. Aspirin therapy (75 mg to 325 mg a day) or a drug called clopidogrel may be prescribed for women at high risk for heart disease.
Aspirin therapy is recommended for women over age 65 to prevent a heart attack and stroke. However, it is only recommended if blood pressure is controlled and the benefit is likely to outweigh the risk of gastrointestinal side effects. Regular use of aspirin is not recommended for healthy women under age 65 to prevent heart attacks.
New guidelines no longer recommend hormone replacement therapy, vitamins E or C, antioxidants, or folic acid to prevent heart disease.
After a heart attack, you will need regular follow-up care to reduce the risk of having a second heart attack. Often, a cardiac rehabilitation program is recommended to help you gradually return to a normal lifestyle. Always follow the exercise, diet, and medication plan prescribed by your doctor.
References Return to top
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.Update Date: 4/23/2009 Updated by: 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.