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 is starved of oxygen and heart cells die.
A hard substance called plaque can build up in the walls of your coronary arteries. This plaque is made up of cholesterol and other cells.
A heart attack may occur when:
Blood platelets stick to tears in the plaque and form a blood clot that blocks blood from flowing to the heart. This is the most common cause of heart attacks.
A slow buildup of this plaque may almost block one of your coronary arteries.
The cause of heart attacks is not always known. Heart attacks may occur:
When you are resting or asleep
After a sudden increase in physical activity
When you are active outside in cold weather
After sudden, severe emotional or physical stress, including an illness
Many risk factors may lead to a heart attack.
A heart attack is a medical emergency. If you have symptoms of a heart attack, call 911 or your local emergency number right away.
DO NOT try to drive yourself to the hospital.
DO NOT WAIT. You are at greatest risk of sudden death in the early hours of a heart attack.
Chest pain is the most common symptom of a 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.
Some people (the elderly, people with diabetes, and women) may have little or no chest pain. Or, they may have unusual symptoms (shortness of breath, fatigue, and weakness). A "silent heart attack" is a heart attack with no symptoms.
Signs and tests
A doctor or nurse 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 fast or uneven pulse.
Your blood pressure may be normal, high, or low.
You will have an electrocardiogram (ECG) to look for heart damage. A troponin blood test can show if you have heart tissue damage. This test can confirm that you are having a heart attack.
After a heart attack, you may feel sad. You may feel anxious and worry about being careful about everything you do. All of these feelings are normal. They go away for most people after 2 or 3 weeks. You may also feel tired when you leave the hospital to go home.
Most people who have had a heart attack take part in a cardiac rehab program.
After a heart attack, your chance of having another one is higher than if you never had a heart attack.
How well you do after a heart attack depends on the damage to your heart muscle and heart valves, and where that damage is located.
If your heart can no longer pump blood out to your body as well as it used to, you may develop heart failure. Abnormal heart rhythms can occur, and they can be life threatening.
Usually a person who has had a heart attack can slowly go back to normal activities, including sexual activity. Discuss your activity level with your health care provider.
Anderson JL. ST segment elevation acute myocardial infarction and complications of myocardial infarction. In: Goldman L, Schafer AI, eds. Cecil Medicine. Philadelphia, Pa: Saunders Elsevier; 2011:chap 73.
Antman EM. ST-segment elevation myocardial infarction: pathology, pathophysiology, and clinical features. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsever; 2011:chap 54.
Cannon CP, Braunwald E. Unstable angina and non-ST elevation myocardial infarction. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsever; 2011:chap 56.
Kushner FG, Hand M, Smith SC Jr, King SB 3rd, Anderson JL, Antman EM, et al. 2009 Focused Updates: ACC/AHA Guidelines for the Management of Patients WithST-Elevation Myocardial Infarction (updating the 2004 Guideline and 2007 Focused Update) and ACC/AHA/SCAI Guidelines on Percutaneous Coronary Intervention(updating the 2005 Guideline and 2007 Focused Update): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2009 Dec 1;120(22):2271-306. Epub 2009 Nov 18.
Wright RS, Anderson JL, Adams CD, et al. 2011 ACCF/AHA Focused Update of the Guidelines for the Management of Patients with Unstable Angina/Non-ST-Elevation Myocardial Infarction (Updating the 2007 Guideline). A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines Developed in Collaboration With the American College of Emergency Physicians, Society for Cardiovascular Angiograpy and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2011;57:1920-1959.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.