Acute coronary syndrome is a term used to describe a range of conditions associated with sudden, reduced blood flow to the heart.

One such condition is a heart attack (myocardial infarction) — when cell death results in damaged or destroyed heart tissue. Even when acute coronary syndrome causes no cell death, the reduced blood flow changes how your heart works and is a sign of a high risk of heart attack.

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

The signs and symptoms of acute coronary syndrome usually begin abruptly. They include:

• Chest pain (angina) or discomfort, often described as aching, pressure, tightness or burning
• Pain spreading from the chest to the shoulders, arms, upper abdomen, back, neck or jaw
• Nausea or vomiting
• Indigestion
• Shortness of breath (dyspnea)
• Sudden, heavy sweating (diaphoresis)
• Lightheadedness, dizziness or fainting
• Unusual or unexplained fatigue
• Feeling restless or apprehensive

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

When to see a doctor

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

Acute coronary syndrome usually results from the buildup of fatty deposits (plaques) in and on the walls of coronary arteries, the blood vessels delivering oxygen and nutrients to heart muscles.

When a plaque 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 of the heart muscles can die. The death of cells — resulting in damage to muscle tissues — is a heart attack (myocardial infarction).

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

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

• Aging
• High blood pressure
• High blood cholesterol
• Cigarette smoking
• Lack of physical activity
• Unhealthy diet
• Obesity or overweight
• Diabetes
• Family history of chest pain, heart disease or stroke
• History of high blood pressure, preeclampsia or diabetes during pregnancy
• COVID-19 infection

If you have signs or symptoms associated with acute coronary syndrome, an emergency room doctor will likely order several tests. Some tests may be done while your doctor is asking you questions about your symptoms or medical history. Tests include:

• Electrocardiogram (ECG). Electrodes attached to your skin measure the electrical activity in your heart. Abnormal or irregular impulses can mean your heart is not working properly due to a lack of oxygen. Certain patterns in electrical signals may show the general location of a blockage. The test may be repeated several times.
• Blood tests. Certain enzymes may be detected in the blood if cell death has resulted in damage to heart tissue. A positive result indicates a heart attack.

The information from these two tests — as well as your signs and symptoms — is used to make a primary diagnosis of acute coronary syndrome. Your doctor can use the information to determine whether your condition can be classified as a heart attack or unstable angina.

Other tests may be done to learn more about your condition, rule out other causes of symptoms, or to help your doctor personalize your diagnosis and treatment.

• Coronary angiogram. This procedure uses X-ray imaging to see your heart's blood vessels. A long, tiny tube (catheter) is threaded through an artery, usually in your arm or groin, to the arteries in your heart. A dye flows through the tube into your arteries. A series of X-rays show how the dye moves through your arteries, revealing any blockages or narrowing. The catheter may also be used for treatments.
• Echocardiogram. An echocardiogram uses sound waves, directed at your heart from a wand-like device, to produce a live image of your heart. An echocardiogram can help determine whether the heart is pumping correctly.
• Myocardial perfusion imaging. This test shows how well blood flows through your heart muscle. A tiny, safe amount of radioactive substance is injected into your blood. A specialized camera takes images of the substance's path through your heart. They show your doctor whether enough blood is flowing through heart muscles and where blood flow is reduced.
• Computerized tomography (CT) angiogram. A CT angiogram uses a specialized X-ray technology that can produce multiple images — cross-sectional 2-D slices — of your heart. These images can detect narrowed or blocked coronary arteries.
• Stress test. A stress test reveals how well your heart works when you exercise. In some cases, you may receive a medication to increase your heart rate rather than exercising. This test is done only when there are no signs of acute coronary syndrome or another life-threatening heart condition when you are at rest. During the stress test, an ECG, echocardiogram or myocardial perfusion imaging may be used to see how well your heart works.

The immediate goals of treatment for acute coronary syndrome are:

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

Long-term treatment goals are to improve overall heart function, manage risk factors and lower the risk of a heart attack. A combination of drugs and surgical procedures may be used to meet these goals.

Medications

Depending on your diagnosis, medications for emergency or ongoing care (or both) may include the following:

• Thrombolytics (clot busters) help dissolve a blood clot that's blocking an artery.
• Nitroglycerin improves blood flow by temporarily widening blood vessels.
• Antiplatelet drugs help prevent blood clots from forming and include aspirin, clopidogrel (Plavix), prasugrel (Effient) and others.
• Beta blockers help relax your heart muscle and slow your 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, allowing the heart to work better. They include lisinopril (Prinivil, Zestril), benazepril (Lotensin) and others.
• Angiotensin receptor blockers (ARBs) help control blood pressure and include irbesartan (Avapro), losartan (Cozaar) and several others.
• Statins lower the amount of cholesterol moving in the blood and may stabilize plaque deposits, making them less likely to rupture. Statins include atorvastatin (Lipitor), simvastatin (Zocor, Flolipid) and several others.

Surgery and other procedures

Your doctor may recommend one of these procedures to restore blood flow to your heart muscles:

• Angioplasty and stenting. In this procedure, your doctor inserts a long, tiny tube (catheter) into the blocked or narrowed part of your artery. A wire with a deflated balloon is passed through the catheter to the narrowed area. The balloon is then inflated, opening the artery by compressing the plaque deposits against your artery walls. A mesh tube (stent) is usually left in the artery to help keep the artery open.
• Coronary bypass surgery. With this procedure, a surgeon takes a piece of blood vessel (graft) from another part of your body and creates a new route for blood that goes around (bypasses) a blocked coronary artery.

Heart healthy lifestyle changes are an important part of heart attack prevention. Recommendations include the following:

• Don't smoke. If you smoke, quit. Talk to your doctor if you need help quitting. Also, avoid secondhand smoke.
• Eat a heart-healthy diet. Eat a diet with lots of fruits and vegetables, whole grains, and moderate amounts of low-fat dairy and lean meats.
• Be active. Get regular exercise and stay physically active. If you have not been exercising regularly, talk to your doctor about the best exercise to begin a healthy and safe routine.
• Check your cholesterol. Have your blood cholesterol levels checked regularly at your doctor's office. Avoid high-fat, high-cholesterol meat and dairy. If your doctor has prescribed a statin or other cholesterol-lowering medication, take it daily as directed by your doctor.
• Control your blood pressure. Have your blood pressure checked regularly as recommended by your doctor. Take blood pressure medicine daily as recommended.
• Maintain a healthy weight. Excess weight strains your heart and can contribute to high cholesterol, high blood pressure, diabetes, heart disease and other conditions.
• Manage stress. To reduce your risk of a heart attack, reduce stress in your day-to-day activities. Rethink work habits and find healthy ways to minimize or deal with stressful events in your life. Talk to your doctor or a mental health care professional if you need help managing stress.
• Drink alcohol in moderation. If you drink alcohol, do so in moderation. Drinking more than one to two alcoholic drinks a day can raise blood pressure.

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

Your description of symptoms provides important information to help an emergency medical team make a diagnosis. Be prepared to answer the following questions.

• When did signs or symptoms appear?
• How long did they last?
• What symptoms are you currently experiencing?
• How would you describe the pain?
• Where is the pain located?
• How would you rate the severity of pain?
• Does anything worsen or lessen the symptoms?