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.

May 16, 2023

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  1. Overview of acute coronary syndromes (ACS). Merck Manual Professional Version. https://www.merckmanuals.com/professional/cardiovascular-disorders/coronary-artery-disease/overview-of-acute-coronary-syndromes-acs. Accessed Jan. 21, 2023.
  2. Varghese T, et al. Non-ST elevation acute coronary syndrome in women and the elderly: Recent updates and stones still left unturned. F1000 Research. 2020; doi:10.12688/f1000research.16492.1.
  3. Reeder GS, et al. Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency room. https://www.uptodate.com/contents/search. Accessed Jan. 21, 2023.
  4. What is coronary heart disease? National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-topics/ischemic-heart-disease. Accessed Jan. 21, 2023.
  5. Lopez-Jimenez F (expert opinion). Mayo Clinic. Feb. 7, 2023.
  6. Bergmark BA, et al. Acute coronary syndromes. The Lancet. 2022; doi: 10.1016/S0140-6736(21)02391-6.
  7. Guedeney P, et al. Diagnosis and management of acute cornary syndrome: What is new and why? Insight from the 2020 European Society of Cardiology Guidelines. Journal of Clinical Medicine. 2020; doi:10.3390/jcm9113474.
  8. Lawton JS, al. 2021 ACC/AHA/SCAI guideline for coronary artery revascularization: Executive summary: A report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022; doi: 10.1161/CIR.0000000000001039.
  9. Myocardial perfusion imaging (MPI) test. American Heart Association. https://www.heart.org/en/health-topics/heart-attack/diagnosing-a-heart-attack/myocardial-perfusion-imaging-mpi-test. Accessed March 16, 2023.
  10. Soman P, et al. Noninvasive testing and imaging for diagnosis in patients at low to intermediate risk for acute coronary syndrome. https://www.uptodate.com/contents/search. Accessed Jan. 21, 2023.
  11. Types of heart medications. American Heart Association. https://www.heart.org/en/health-topics/heart-attack/treatment-of-a-heart-attack/cardiac-medications. Accessed Jan. 21, 2023.
  12. Heart procedures and surgeries. American Heart Association. https://www.heart.org/en/health-topics/heart-attack/treatment-of-a-heart-attack/cardiac-procedures-and-surgeries. Accessed Jan. 21, 2023.
  13. 2020-2025 Dietary Guidelines for Americans. U.S. Department of Health and Human Services and U.S. Department of Agriculture. https://www.dietaryguidelines.gov. Accessed March 16, 2023.
  14. Lloyd-Jones DM, et al. Life's essential 8: Updating and enhancing the American Heart Association's construct of cardiovascular health: A presidential advisory from the American Heart Association. Circulation. 2022; doi:10.1161/CIR.0000000000001078.
  15. American Heart Association adds sleep to cardiovascular health checklist. American Heart Association. https://newsroom.heart.org/news/american-heart-association-adds-sleep-to-cardiovascular-health-checklist. Accessed March 16, 2023.