Acute coronary syndrome
Syndrome of decreased coronary blood flow causing heart muscle damage.
Wikipedia / Wikimedia Commons
Acute coronary syndrome (ACS) happens when blood flow through the coronary arteries drops, leaving part of the heart muscle unable to work properly or causing it to die. The main symptom is a pressure-like chest pain centered in the chest, which often spreads to the left shoulder or jaw and comes with nausea and sweating. However, many people—especially women, older adults, and those with diabetes—experience symptoms other than chest pain.
ACS is divided into three types based on ECG findings and blood tests for cardiac biomarkers like troponin: ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), and unstable angina. In STEMI, a coronary artery is fully blocked, leading to heart muscle death and ST elevation on the ECG. In NSTEMI, the artery is partially blocked, also causing heart muscle death, which may show up on the ECG. Unstable angina involves heart muscle ischemia without cell death or injury.
ACS differs from stable angina, which comes on during physical activity or stress and goes away with rest. Unstable angina appears suddenly, often at rest or with little exertion, or at a lower activity level than the person’s usual angina (called crescendo angina). New-onset angina is also considered unstable, as it points to a new problem in a coronary artery.
**Signs and symptoms** Symptoms across the acute coronary syndromes are similar. The key sign is chest pain described as tightness, pressure, or burning. It is usually felt around or over the chest and can spread to the arm, shoulder, neck, back, upper abdomen, or jaw. Sweating, nausea, or shortness of breath may accompany it. The term "atypical" was once used for chest pain not typical of heart issues, but this is no longer recommended; "noncardiac" is now preferred for pain with a low likelihood of heart origin.
In unstable angina, symptoms can occur at rest or with minimal effort. They may last longer than stable angina, resist rest or medication, and worsen over time. While ACS is often linked to coronary thrombosis, it can also be triggered by cocaine use. Chest pain with cardiac features (angina) can also result from severe anemia, very slow or fast heart rate, low or high blood pressure, severe aortic valve stenosis, pulmonary artery hypertension, and other conditions.
**Pathophysiology** In ACS, atheroma rupture is found in about 60% of cases, compare
- field
- Cardiology
- known_for
- Syndrome of decreased coronary blood flow causing heart muscle dysfunction or death
- subtypes
- STEMI, NSTEMI, unstable angina
- cardinal_symptom
- Centrally located pressure-like chest pain
- common_cause
- Atheroma rupture (60%) or erosion (30%) leading to thrombus formation
Lore & Background
Acute coronary syndrome is subdivided into three scenarios depending primarily on the presence of electrocardiogram (ECG) changes and blood test results: ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), or unstable angina. STEMI is characterized by complete blockage of a coronary artery resulting in necrosis of part of the heart muscle indicated by ST elevation on ECG. NSTEMI is characterized by a partially blocked coronary artery resulting in necrosis that may be indicated by ECG changes. Unstable angina is characterized by ischemia of the heart muscle that does not result in cell injury or necrosis.
Reader's Guide
Acute coronary syndrome represents a critical medical condition requiring rapid diagnosis and treatment. Its significance lies in the high morbidity and mortality associated with myocardial infarction and unstable angina. The distinction between STEMI, NSTEMI, and unstable angina guides immediate management: STEMI typically requires urgent reperfusion via thrombolytics or percutaneous coronary intervention within specific time frames, while NSTE-ACS is managed with antiplatelet therapy, anticoagulation, and delayed angiography if appropriate. The syndrome's pathophysiology most commonly involves atheroma rupture or erosion leading to thrombus formation. Prevention focuses on controlling atherosclerosis risk factors, and smoking bans have been associated with reduced hospital admissions. Prognosis can be estimated using risk scores such as TIMI and GRACE, which help identify high-risk patients. The condition also has less common causes including spontaneous coronary artery dissection and ischemia without obstructive coronary artery disease.
Did You Know?
- Many people with acute coronary syndromes present with symptoms other than chest pain, particularly women, older people, and people with diabetes mellitus.
- In plaque rupture, the content is lipid rich, collagen poor, with abundant macrophage-predominant inflammation and a thin fibrous cap.
- After a ban on smoking in all enclosed public places in Scotland in March 2006, there was a 17% reduction in hospital admissions for acute coronary syndrome.
- Cocaine-associated ACS should be managed similarly to other ACS except beta blockers should not be used and benzodiazepines should be administered early.
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