Acute Coronary Syndrome
A sudden, dangerous drop in blood flow to the heart muscle
Quick Facts
- Type: Cardiovascular emergency
- Includes: Heart attack and unstable angina
- Main cause: Blocked or narrowed coronary arteries
- Urgency: Medical emergency — call emergency services
Overview
Acute coronary syndrome (ACS) is an umbrella term for situations in which blood flow to the heart muscle is suddenly reduced or cut off. It includes heart attack (myocardial infarction) and unstable angina, in which chest pain occurs at rest or worsens unexpectedly. ACS is a medical emergency.
Most cases happen when a fatty plaque inside a coronary artery ruptures and a blood clot forms, narrowing or blocking the artery. Without enough blood and oxygen, heart muscle can become damaged within minutes to hours. If you or someone else has signs of ACS, call emergency services immediately — fast treatment saves heart muscle and lives.
Doctors often divide ACS into categories based on test results, which guide how urgently the blocked artery must be reopened. What these categories share is a sudden, dangerous drop in the heart's blood supply. The longer the heart muscle goes without enough blood, the more damage occurs, which is why every minute counts and why calling for emergency help quickly makes such a difference to the outcome.
Symptoms
The classic symptom is chest pain or pressure, but signs vary and can be subtle, especially in women, older adults, and people with diabetes:
- Chest pain, pressure, tightness, or squeezing, often in the center or left chest
- Pain spreading to the arm, shoulder, jaw, neck, or back
- Shortness of breath
- Cold sweat, nausea, or vomiting
- Lightheadedness or fainting
- Unusual fatigue or a sense of impending doom
These can signal a heart attack. Do not wait — call emergency services right away. Chest discomfort lasting more than a few minutes, or that goes away and comes back, needs emergency evaluation.
Causes
ACS usually results from coronary artery disease, in which fatty deposits (plaques) build up inside the arteries that supply the heart. The acute event is typically caused by:
- Plaque rupture and clotting: A plaque breaks open and a blood clot forms, suddenly narrowing or blocking the artery.
- Severe narrowing: Advanced plaque buildup that critically limits blood flow.
- Coronary spasm: A sudden tightening of an artery, less commonly.
The degree and duration of blockage determine whether the result is unstable angina or a heart attack with muscle damage.
Risk Factors
- High blood pressure and high cholesterol
- Smoking
- Diabetes
- Overweight or obesity and physical inactivity
- A family history of early heart disease
- Older age
- Existing coronary artery disease or a prior heart attack
Diagnosis
ACS is diagnosed urgently using:
- Electrocardiogram (ECG): A rapid test that detects signs of reduced blood flow or a heart attack and guides immediate treatment.
- Blood tests (cardiac troponin): Detect proteins released when heart muscle is injured.
- Coronary angiography: Imaging of the heart's arteries to find and often treat the blockage.
- Other imaging: Such as echocardiography to assess heart function.
Treatment
Treatment aims to restore blood flow quickly and protect the heart:
- Emergency medicines: Such as aspirin and other blood thinners, plus medicines to ease the heart's workload and relieve pain.
- Opening the artery: Angioplasty with a stent, or sometimes clot-dissolving medication, to reopen a blocked artery.
- Bypass surgery: For certain patterns of severe blockage.
- Long-term care: Medications, cardiac rehabilitation, and lifestyle changes to prevent another event.
Because time is critical, calling emergency services at the first signs gives the best chance of limiting heart damage.
Prevention
You can lower the risk of ACS by addressing heart disease risk factors:
- Not smoking, and avoiding secondhand smoke
- Keeping blood pressure, cholesterol, and blood sugar in healthy ranges
- Eating a heart-healthy diet and staying physically active
- Maintaining a healthy weight
- Taking prescribed heart medications as directed
- Attending regular checkups, especially with a family or personal history of heart disease
When to See a Doctor
Acute coronary syndrome is a medical emergency. Call emergency services immediately if you or someone else has:
- Chest pain, pressure, or tightness lasting more than a few minutes
- Pain spreading to the arm, jaw, neck, shoulder, or back
- Shortness of breath, cold sweat, nausea, or lightheadedness
- A feeling of impending doom with chest discomfort
Do not drive yourself if you can avoid it, and do not wait to see if symptoms pass. Fast treatment saves heart muscle and lives.
Frequently Asked Questions
What is acute coronary syndrome?
It is an umbrella term for sudden, serious reductions in blood flow to the heart, including heart attack and unstable angina. It is a medical emergency caused most often by a blood clot forming on a ruptured plaque in a coronary artery.
What should I do if I think I am having a heart attack?
Call emergency services right away. Do not wait to see if the pain passes, and avoid driving yourself if possible. Fast treatment to reopen a blocked artery limits heart muscle damage and can be lifesaving.
What is the difference between a heart attack and unstable angina?
Both are forms of acute coronary syndrome. Unstable angina is chest pain at rest or that suddenly worsens without permanent heart muscle damage, while a heart attack involves actual injury to the heart muscle, detected by blood tests and ECG changes.
Can acute coronary syndrome happen without chest pain?
Yes. Some people, particularly women, older adults, and people with diabetes, may have shortness of breath, nausea, sweating, fatigue, or jaw or back discomfort instead of obvious chest pain. Any sudden, unexplained symptoms suggesting a heart problem should be treated as an emergency.
How is acute coronary syndrome treated?
Treatment includes emergency medicines such as aspirin and other blood thinners, and procedures to reopen the blocked artery, usually angioplasty with a stent or clot-dissolving medication. Long-term care involves medications, cardiac rehabilitation, and lifestyle changes to prevent another event.
References
- American Heart Association. Acute Coronary Syndrome.
- Mayo Clinic. Coronary artery disease — Symptoms and causes.
- National Heart, Lung, and Blood Institute (NHLBI). Heart Attack.
- MedlinePlus, U.S. National Library of Medicine. Acute coronary syndrome.