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Potentially life-threatening emergency
Acute coronary syndrome
Other Resources UpToDate PubMed
Potentially life-threatening emergency

Acute coronary syndrome

Contributors: Scott Echternacht, Michael W. Winter MD, Paritosh Prasad MD, Ryan Hoefen MD, PhD
Other Resources UpToDate PubMed

Synopsis

Acute coronary syndrome (ACS) is caused by acute myocardial ischemia (insufficient coronary blood flow to meet the metabolic demand of the downstream myocardial tissue). When the severity and duration of ischemia are sufficient to cause necrosis of the downstream myocardial tissue, the result is a myocardial infarction. The most prominent presenting symptom is usually severe chest pain, often described as a crushing pressure-like sensation, that may radiate to the left shoulder and/or jaw. Associated symptoms may include diaphoresis and nausea. Some patients present with shortness of breath, dizziness, back pain, nausea, and/or diaphoresis in the absence of chest discomfort. Patients most likely to have these "atypical" presentations include women, elderly patients, and patients with diabetes.

ACS is most commonly due to coronary artery atherosclerosis, the long-term result of a cascade of chronic inflammatory processes that lead to the development of plaques. The fibrous cap over the plaques may be unstable and can rupture, leading to thrombosis, which can partially or completely obstruct blood flow. Risk factors for atherosclerotic disease include hypertension, hyperlipidemia, diabetes, smoking, increased weight, increased age, male sex, renal insufficiency, sedentary lifestyle, Western diet, and family history of atherosclerotic disease. In the United States, ACS is most common in the sixth decade of life and has a male to female ratio of 3:2.

Less common causes of arterial obstruction that can result in ACS include embolic events, vasospasm, and coronary artery dissection. ACS may also occur as a result of diffuse myocardial ischemia and infarction in the setting of noncardiac disease such as severe anemia, hypoxemia, or sepsis. Rarely, acute rupture of the ventricular wall can occur in late-presenting cases of myocardial infarction.

ACS is a major cause of morbidity and mortality throughout the world; however, while overall cases have declined, cases of non-ST-elevation myocardial infarction (NSTEMI) have risen due to increasingly sensitive troponin assays. 

ACS includes the following 3 diagnoses, which represent a spectrum of disease severity and are differentiated by ECG findings and serum cardiac enzyme (troponin) levels:
  • ST-elevation myocardial infarction (STEMI) – New ST segment elevations on ECG and elevated cardiac enzyme levels.
  • Non-ST-elevation myocardial infarction (NSTEMI) – Elevated cardiac enzyme levels without ST elevations. ST depressions and/or T-wave inversions may or may not be present on ECG.
  • Unstable angina (UA) – Chest pain and/or other symptoms of ischemia that are new, worsening, or occurring at rest in the absence of abnormal cardiac enzyme levels. ST segment depression and T-wave inversion may or may not be present on ECG. This is distinguished from stable angina, in which chronic coronary artery disease causes chest discomfort that is provoked by exertion and resolves with rest in a predictable manner.

Codes

ICD10CM:
I20.0 – Unstable angina
I21.9 – Acute myocardial infarction, unspecified

SNOMEDCT:
394659003 – Acute coronary syndrome

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Cardiac causes of chest pain: Pulmonary causes: Gastrointestinal causes: Musculoskeletal causes: Psychiatric causes: Infectious causes:

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed:04/20/2020
Last Updated:01/26/2021
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Potentially life-threatening emergency
Acute coronary syndrome
Acute coronary syndrome (Prodromal Symptoms) : Chest pain, Fatigue, Malaise, Dyspnea
Copyright © 2021 VisualDx®. All rights reserved.