Acute coronary syndrome (ACS) is a

syndrome A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek language, Greek σύνδρομον, meaning "concurrence". When a sy ...

due to decreased

blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory system is controlled by homeostasis, homeostatic mechanisms of autoregulation, just as hydrau ...

in the

coronary arteries The coronary arteries are the arteries, arterial blood vessels of coronary circulation, which transport oxygenated blood to the Cardiac muscle, heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any ...

such that part of the heart muscle is unable to function properly or dies. The most common symptom is centrally located pressure-like

chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with n ...

, often radiating to the left shoulder or angle of the jaw, and associated with

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

and sweating. Many people with acute coronary syndromes present with symptoms other than chest pain, particularly women, older people, and people with

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

. Acute coronary syndrome is subdivided in three scenarios depending primarily on the presence of electrocardiogram (ECG) changes and blood test results (a change in cardiac biomarkers such as troponin levels):

ST elevation myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom is retr ...

(STEMI), non-ST elevation myocardial infarction (NSTEMI), or

unstable angina In dynamical systems instability means that some of the outputs or internal states increase with time, without bounds. Not all systems that are not stable are unstable; systems can also be marginally stable or exhibit limit cycle behavior ...

. STEMI is characterized by complete blockage of a coronary artery resulting in

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

of part of the heart muscle indicated by ST elevation on ECG, NSTEMI is characterized by a partially blocked coronary artery resulting in necrosis of part of the heart muscle that may be indicated by ECG changes, and unstable angina is characterised by ischemia of the heart muscle that does not result in cell injury or necrosis. ACS should be distinguished from ''stable'' angina, which develops during physical activity or stress and resolves at rest. In contrast with stable angina,

occurs suddenly, often at rest or with minimal exertion, or at lesser degrees of exertion than the individual's previous angina ("crescendo angina"). New-onset angina is also considered unstable angina, since it suggests a new problem in a coronary artery.

Signs and symptoms

Symptoms of the acute coronary syndromes are similar. The cardinal symptom of critically decreased blood flow to the heart is

, experienced as tightness, pressure, or burning. Localization is most commonly around or over the chest and may radiate or be located to the arm, shoulder, neck, back, upper abdomen, or jaw. This may be associated with sweating,

, or

shortness of breath Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that con ...

. Previously, the word "atypical" was used to describe chest pain not typically heart-related, however, this word is not recommended and has been replaced by "noncardiac" to describe chest pain that indicates a low likelihood of heart-related pain. In unstable angina, symptoms may appear on rest or on minimal exertion. The symptoms can last longer than those in stable angina, can be resistant to rest or medicine, and can get worse over time. Though ACS is usually associated with coronary thrombosis, it can also be associated with

cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

use. Chest pain with features characteristic of cardiac origin (angina) can also be precipitated by profound

anemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availabl ...

, brady- or

tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal ...

(excessively slow or rapid heart rate), low or

high blood pressure Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major ri ...

, severe aortic valve stenosis (narrowing of the valve at the beginning of the

aorta The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

), pulmonary artery hypertension and a number of other conditions.

Pathophysiology

In those who have ACS,

atheroma An atheroma, or atheromatous plaque, is an abnormal accumulation of material in the tunica intima, inner layer of an arterial wall. The material consists of mostly macrophage, macrophage cells, or debris, containing lipids, calcium and a variabl ...

rupture is most commonly found 60% when compared to atheroma erosion (30%), thus causes the formation of

thrombus A thrombus ( thrombi) is a solid or semisolid aggregate from constituents of the blood (platelets, fibrin, red blood cells, white blood cells) within the circulatory system during life. A blood clot is the final product of the blood coagulatio ...

which block the coronary arteries. Plaque rupture is responsible for 60% in ST elevated

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...

(STEMI) while plaque erosion is responsible for 30% of the STEMI and vice versa for Non ST elevated myocardial infarction (NSTEMI). In plaque rupture, the content of the plaque is lipid rich, collagen poor, with abundant inflammation which is

macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

predominant, and covered with a thin fibrous cap. Meanwhile, in plaque erosion, the plaque is rich with

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...

proteoglycan Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to w ...

, glycoaminoglycan, but without fibrous caps, no inflammatory cells, and no large lipid core. After the

are unblocked, there is a risk of reperfusion injury due spreading inflammatory mediators throughout the body. Investigations is still underway on the role of cyclophilin D in reducing the reperfusion injury. Other, less common, causes of acute coronary syndrome include spontaneous coronary artery dissection, ischemia in the absence of obstructive coronary artery disease (INOCA), and myocardial infarction in the absence of obstructive coronary artery disease (MINOCA).

Diagnosis

Electrocardiogram

In the setting of acute chest pain, the electrocardiogram (ECG or EKG) is the investigation that most reliably distinguishes between various causes. The ECG should be done as early as practicable, including in the ambulance if possible. ECG changes indicating acute heart damage include: ST elevation, new left bundle branch block and ST depression amongst others. The absence of ECG changes does not immediately distinguish between unstable angina and NSTEMI.

Blood tests

Change in levels of cardiac biomarkers, such as

troponin I Troponin I is a cardiac and skeletal muscle protein family. It is a part of the troponin protein complex, where it binds to actin in thin myofilaments to hold the actin-tropomyosin complex in place. Troponin I prevents myosin from binding to act ...

and

troponin T Troponin T (shortened TnT or TropT) is a part of the troponin complex, which are proteins integral to the contraction of skeletal and heart muscles. They are expressed in skeletal and cardiac myocytes. Troponin T binds to tropomyosin and help ...

, are indicative of

including both STEMI and NSTEMI, however their levels are not affected in

Prediction scores

A combination of cardiac biomarkers and risk scores, such as ''HEART'' score and '' TIMI'' score, can help assess the possibility of

in the emergency setting.

Prevention

Acute coronary syndrome often reflects a degree of damage to the coronaries by

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

. Primary prevention of atherosclerosis is controlling the risk factors: healthy eating, exercise, treatment for

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

and

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

, avoiding

smoking Smoking is a practice in which a substance is combusted, and the resulting smoke is typically inhaled to be tasted and absorbed into the bloodstream of a person. Most commonly, the substance used is the dried leaves of the tobacco plant, whi ...

and controlling

cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

levels; in patients with significant risk factors,

aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...

has been shown to reduce the risk of cardiovascular events. Secondary prevention is discussed in

. After a ban on smoking in all enclosed public places was introduced in Scotland in March 2006, there was a 17% reduction in hospital admissions for acute coronary syndrome. 67% of the decrease occurred in non-smokers.

Treatment

People with presumed ACS are typically treated with

clopidogrel Clopidogrel, sold under the brand name Plavix among others, is an antiplatelet drug, antiplatelet medication used to reduce the risk of Cardiovascular disease, heart disease and stroke in those at high risk. It is also used together with aspi ...

or ticagrelor,

nitroglycerin Nitroglycerin (NG) (alternative spelling nitroglycerine), also known as trinitroglycerol (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by ...

, and, if the chest discomfort persists,

morphine Morphine, formerly also called morphia, is an opiate that is found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (''Papaver somniferum''). It is mainly used as an analgesic (pain medication). There are ...

. Other analgesics such as

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...

are of unknown benefit.

Angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...

is recommended in those who have either new ST elevation or a new left or right bundle branch block on their ECG. Unless the person has low oxygen levels additional oxygen does not appear to be useful.

STEMI

If the ECG confirms changes suggestive of

( ST elevation in specific leads, a new left bundle branch block or a true posterior MI pattern), thrombolytics may be administered or

percutaneous coronary intervention Percutaneous coronary intervention (PCI) is a minimally invasive non-surgical procedure used to treat stenosis, narrowing of the coronary artery, coronary arteries of the heart found in coronary artery disease. The procedure is used to place and ...

may be performed. In the former, medication is injected that stimulates

fibrinolysis Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other c ...

, destroying blood clots obstructing the

. In the latter, a flexible catheter is passed via the femoral or

radial artery In human anatomy, the radial artery is the main artery of the lateral aspect of the forearm. Structure The radial artery arises from the bifurcation of the brachial artery in the antecubital fossa. It runs distally on the anterior part of the ...

and advanced to the heart to identify blockages in the

. When occlusions are found, they can be intervened upon mechanically with

angioplasty Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty, is a minimally invasive procedure, minimally invasive endovascular surgery, endovascular Medical procedure, procedure used to widen narrowed or obstructe ...

and usually

stent In medicine, a stent is a tube usually constructed of a metallic alloy or a polymer. It is inserted into the Lumen (anatomy), lumen (hollow space) of an anatomic vessel or duct to keep the passageway open. Stenting refers to the placement of ...

deployment if a lesion, termed the ''culprit'' lesion, is thought to be causing myocardial damage. Data suggest that rapid triage, transfer and treatment is essential. The time frame for door-to-needle thrombolytic administration according to American College of Cardiology (ACC) guidelines should be within 30 minutes, whereas the door-to-balloon

(PCI) time should be less than 90 minutes. It was found that

thrombolysis Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of thrombus, blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism ( ...

is more likely to be delivered within the established ACC guidelines among patients with STEMI as compared to PCI according to a 2009 case control study.

NSTEMI and NSTE-ACS

If the ECG does not show typical changes consistent with STEMI, the term "non-ST segment elevation ACS" (NSTE-ACS) may be used and encompasses "non-ST elevation MI" (NSTEMI) and unstable angina. The accepted management of unstable angina and acute coronary syndrome is therefore empirical treatment with aspirin, a second platelet inhibitor such as clopidogrel, prasugrel or ticagrelor, and heparin (usually a low-molecular weight heparin), with intravenous

and

opioid Opioids are a class of Drug, drugs that derive from, or mimic, natural substances found in the Papaver somniferum, opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, ...

s if the pain persists. The heparin-like drug known as fondaparinux appears to be better than enoxaparin. If there is no evidence of ST segment elevation on the electrocardiogram, delaying urgent

until the next morning is not inferior to doing so immediately. Using

statins Statins (or HMG-CoA reductase inhibitors) are a class of medications that lower cholesterol. They are prescribed typically to people who are at high risk of cardiovascular disease. Low-density lipoprotein (LDL) carriers of cholesterol play ...

in the first 14 days after ACS reduces the risk of further ACS.

Cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

-associated ACS should be managed in a manner similar to other patients with acute coronary syndrome except

beta blocker Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms ( arrhythmia), and to protect the heart from a second heart attack after a first heart attack ( secondary prevention ...

s should not be used and

benzodiazepines Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat co ...

should be administered early.

Prognosis

Prediction scores

The TIMI risk score can identify high risk patients in ST-elevation and non-ST segment elevation MI ACS and has been independently validated. Based on a global registry of 102,341 patients, th
GRACE risk score
stimates in-hospital, 6 months, 1 year, and 3-year mortality risk after a heart attack. It takes into account clinical (blood pressure, heart rate, EKG findings) and medical history. Nowadays, GRACE risk score is also used within non-ST elevation ACS patients as a high-risk criteria(GRACE score > 140), which may favor early invasive strategy within 24 hours of the heart attack.

Biomarkers

Coronary CT angiography combined with troponin levels is also helpful to triage those who are susceptible to ACS. F-fluoride

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

is also helpful in identifying those with high risk, lipid-rich coronary plaques.

Day of admission

Studies have shown that for ACS patients, weekend admission is associated with higher mortality and lower utilization of invasive cardiac procedures, and those who did undergo these interventions had higher rates of mortality and complications than their weekday counterparts. This data leads to the possible conclusion that access to diagnostic/interventional procedures may be contingent upon the day of admission, which may impact mortality. This phenomenon is described as weekend effect.

Research

A study published in 2024 found that women with acute coronary syndrome in India experience worse outcomes.

References

External links

{{DEFAULTSORT:Acute Coronary Syndrome Medical emergencies Ischemic heart diseases Syndromes affecting the heart