Acute coronary syndrome


Acute coronary syndrome is a term that describes a range of conditions related to sudden, reduced blood flow to the heart. These conditions include a heart attack and unstable angina.

A heart attack happens when cell death damages or destroys heart tissue. A heart attack also is known as a myocardial infarction.

Unstable angina occurs when blood flow to the heart decreases. It's not severe enough to cause cell death or a heart attack. But the reduced blood flow may increase your risk of a heart attack.

Acute coronary syndrome often causes severe chest pain or discomfort. It is a medical emergency that needs a diagnosis and care right away. The goals of treatment include improving blood flow, treating complications and preventing future problems.


The symptoms of acute coronary syndrome usually begin suddenly. They include:

  • Chest pain or discomfort. This is often described as aching, pressure, tightness or burning. Chest pain also is called angina.
  • Pain that starts in the chest and spreads to other parts of the body. These areas include the shoulders, arms, upper belly area, back, neck or jaw.
  • Nausea or vomiting.
  • Indigestion.
  • Shortness of breath, also called dyspnea.
  • Sudden, heavy sweating.
  • Racing heartbeat.
  • Feeling lightheaded or dizzy.
  • Fainting.
  • Unusual fatigue.

Chest pain or discomfort is the most common symptom. But symptoms may vary quite a bit depending on your age, sex and other medical conditions. You're more likely to have symptoms without chest pain or discomfort if you're a woman, an older adult or have diabetes.

When to see a doctor

Acute coronary syndrome is a medical emergency. Chest pain or discomfort can be a symptom of many life-threatening conditions. Get emergency help for a diagnosis and appropriate care right away. Do not drive yourself to the hospital.


Acute coronary syndrome usually results from the buildup of fatty deposits on the walls of blood vessels that deliver blood, oxygen and nutrients to heart muscles. Fatty deposits also are called plaque. The blood vessels that supply the heart also are known as coronary arteries.

When a fatty deposit ruptures or splits, a blood clot forms. This clot blocks the flow of blood to heart muscles.

When the supply of oxygen to cells is too low, cells in the heart muscles can die. The death of cells results in damage to muscle tissues. This is called a heart attack.

Even when there is no cell death, the drop in oxygen still results in heart muscles that don't work the way they should. This change may be short-lived or permanent. When acute coronary syndrome doesn't result in cell death, it is called unstable angina.

Risk factors

The risk factors for acute coronary syndrome are the same as those for other types of heart disease. Risk factors include:

  • Getting older.
  • High blood pressure.
  • High blood cholesterol.
  • Smoking tobacco.
  • Lack of physical activity.
  • Eating an unhealthy diet.
  • Obesity or overweight.
  • Diabetes.
  • Personal or family history of chest pain, heart attacks or stroke.
  • History of high blood pressure, preeclampsia or diabetes during pregnancy, and early menopause.
  • COVID-19 infection.


Acute coronary syndrome requires emergency medical care at a hospital. Tests are done to check the heart and determine the cause. Some tests may be done while your health care team asks you questions about your symptoms or medical history.

Tests for acute coronary syndrome may include:

  • Electrocardiogram (ECG or EKG). This quick test measures the heart's electrical activity. Sensors called electrodes are attached to the chest and sometimes to the arms or legs. Changes in the heartbeat may mean the heart is not working properly. Certain patterns in electrical signals may show the general location of a blockage. The test may be repeated several times.
  • Blood tests. Certain heart proteins slowly leak into the blood after heart damage from a heart attack. Blood tests can be done to check for these proteins.

Your symptoms and test results can help your health care team make a diagnosis of acute coronary syndrome. This information also can help classify your condition as a heart attack or unstable angina.

Other tests may be done to learn more about your condition and rule out other causes of symptoms. The tests also may help determine treatment.

  • Coronary angiogram. This test helps health care providers see blockages in the heart arteries. A long, thin flexible tube called a catheter is inserted in a blood vessel, usually in the groin or wrist. It's guided to the heart. Dye flows through the catheter to arteries in the heart. A series of X-rays show how the dye moves through the arteries. The catheter also may be used for treatment.
  • Echocardiogram. This test uses sound waves to create pictures of the beating heart. It shows how blood flows through the heart and heart valves. An echocardiogram can help determine whether the heart is pumping correctly.
  • Myocardial perfusion imaging. This test shows how well blood flows through the heart muscle. A tiny, safe amount of radioactive substance is given by IV. A specialized camera takes pictures of the substance as it travels through the heart. The test helps find areas of poor blood flow or damage in the heart.
  • Computerized tomography (CT) angiogram. This test looks at the arteries that supply blood to the heart. It uses a powerful X-ray machine to create images of the heart and its blood vessels.
  • Stress test. A stress test shows how well your heart works when you exercise. It often involves walking on a treadmill or riding a stationary bike while the heart is checked. If you can’t exercise, you might be given medicine. This test is done only when you have no symptoms of acute coronary syndrome or another life-threatening heart condition when you are at rest. Other tests may be done during the stress test to see how well the heart works.


The immediate goals of treatment for acute coronary syndrome are to:

  • Relieve pain and distress.
  • Improve blood flow.
  • Restore heart function quickly and as much as possible.

Long-term treatment goals are to help the heart work better, manage risk factors and lower the risk of a heart attack. Treatment may include medicine and surgical procedures.


Depending on your diagnosis, medicines may include:

  • Clot busters help break up a blood clot that's blocking an artery. These drugs also are known as thrombolytics.
  • Nitroglycerin improves blood flow by temporarily widening blood vessels.
  • Anti-platelet drugs help prevent blood clots from forming. They include aspirin, clopidogrel (Plavix) and prasugrel (Effient).
  • Beta blockers help relax the heart muscle and slow the heart rate. They decrease the demand on your heart and lower blood pressure. Examples include metoprolol (Lopressor, Toprol-XL) and nadolol (Corgard).
  • Angiotensin-converting enzyme (ACE) inhibitors widen blood vessels and improve blood flow. This helps the heart to work better. Examples include lisinopril (Zestril), benazepril (Lotensin) and others.
  • Angiotensin receptor blockers (ARBs) help control blood pressure. They include irbesartan (Avapro), losartan (Cozaar) and others.
  • Statins lower the amount of cholesterol in the blood. They may stabilize fatty deposits, making them less likely to rupture and form a blood clot. Statins include atorvastatin (Lipitor), simvastatin (Zocor, Flolipid) and others.
  • Other cholesterol-lowering medications such as ezetimibe (Zetia).

Surgery and other procedures

Your health care provider may recommend one of these treatments to restore blood flow to the heart:

  • Angioplasty and stenting. This treatment uses a thin, flexible tube and tiny balloon to open clogged heart arteries. A surgeon inserts the tube in a blood vessel, usually in the groin or wrist, and guides it to the narrowed heart artery. A wire with a deflated balloon on the tip goes through the tube. The balloon is inflated, widening the artery. The balloon is deflated and removed. A small mesh tube is usually placed in the artery to help keep it open. The mesh tube also is called a stent.
  • Coronary artery bypass surgery. This major surgery involves taking a healthy blood vessel from the chest or leg area. This piece of healthy tissue is called a graft. A surgeon attaches the ends of the graft below a blocked heart artery. This creates a new path for blood to flow to the heart.

Lifestyle and home remedies

Heart-healthy lifestyle changes are an important part of preventing a heart attack. Lifestyle changes include the following:

  • Don't smoke. If you smoke, quit. Talk to your health care team if you need help quitting. Also avoid secondhand smoke.
  • Eat a heart-healthy diet. Choose fruits, vegetables and whole grains. Limit low-fat dairy products and lean meats.
  • Be active. Regular exercise helps improve heart health. As a general goal, aim for at least 30 minutes of moderate or vigorous physical activity five or more days a week. If you have not been exercising, talk to your health care team about the best way to begin a healthy and safe exercise routine.
  • Check your cholesterol. Have your blood cholesterol levels checked regularly at a medical office. Avoid high-fat, high-cholesterol meat and dairy. Take a statin or other cholesterol-lowering medicine daily as directed by your health care provider.
  • Control your blood pressure. Have your blood pressure checked regularly by your health care provider. Take blood pressure medicine daily as recommended.
  • Maintain a healthy weight. Too much weight strains the heart. It also can lead to high cholesterol, high blood pressure, diabetes, heart disease and other conditions. Talk with your care team to set realistic goals for weight.
  • Manage stress. Getting more exercise, practicing mindfulness and connecting with others in support groups are some ways to ease stress. Talk to your health care team or a mental health care professional if you need help managing stress.
  • Limit alcohol. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
  • Practice good sleep habits. Poor sleep may increase the risk of heart disease and other chronic conditions. Adults should aim to get 7 to 9 hours of sleep daily. Go to bed and wake at the same time every day, including on weekends. If you have trouble sleeping, talk to your health care team about strategies that might help.

Preparing for an appointment

If you have sudden chest pain or other symptoms of acute coronary syndrome, get emergency care right away or call 911.

How you describe your symptoms helps an emergency medical team make a diagnosis. Be prepared to answer the following questions.

  • When did the symptoms start?
  • How long did they last?
  • What symptoms are you currently having?
  • How would you describe the pain?
  • Where is the pain located?
  • How would you rate the severity of pain?
  • Does anything make the symptoms better or worse?

Last Updated May 16, 2023

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