Acute coronary syndrome

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Acute coronary syndrome (ACS) is a group of cardiac diagnoses along a spectrum of severity due to the interruption of coronary blood flow to the myocardium, which in decreasing severity are:

ST elevation myocardial infarction (STEMI)
non-ST elevation myocardial infarction (NSTEMI)
unstable angina

Stable angina is not considered an ACS.

Epidemiology

Of all patients who present to emergency departments with symptoms of ACS, only 20-25% will have ACS confirmed as their discharge diagnosis ^1,2.

Pathology

Aetiology

The most common cause by far is atherosclerotic plaque rupture in coronary artery disease. Other less common causes include:

aortic or coronary artery dissection
vasculitis
connective tissue diseases
drugs: cocaine
coronary artery spasm

Unusual variants:

Kounis syndrome: allergic / hypersensivity precipitant

Differential diagnosis

Several other pathological entities may mimic an acute coronary syndrome in both electrocardiographic appearance and clinical presentation;

the differential diagnosis for ST segment elevation on the ECG includes ⁵:
- myocarditis and/or pericarditis
- left ventricular hypertrophy
- left ventricular aneurysm
- takotsubo cardiomyopathy
- electrolyte abnormalities
  - including hyperkalemia and hypercalcemia
- acute pulmonary embolism
- coronary artery vasospasm
- acute CNS pathology
  - including subarachnoid hemorrhage and intracranial hemorrhage
- benign early repolarization
- elevated intraabdominal/intrathoracic pressure
  - critically ill patients with free fluid and/or air in their thorax/abdominal cavity may, rarely, present with bizarre ECG patterns, including ST segment elevations
    - the "spiked helmet sign" refers to the characteristic appearance of the sharp upstroke of the baseline leading into ST elevation ³
    - most commonly noted to occur in massive gastric dilatation, small bowel obstruction, and pneumothorax⁴

Other causes of acute chest pain which may mimic the presentation of ACS include;

thoracic aortic dissection
esophageal rupture
pulmonary embolism
pneumothorax
cardiac tamponade

~~-<a href="/articles/kounis-syndrome">Kounis syndrome</a>: allergic / hypersensivity precipitant</li></ul>~~
+<a href="/articles/kounis-syndrome">Kounis syndrome</a>: allergic / hypersensivity precipitant</li></ul><h4>Differential diagnosis</h4>Several other pathological entities may mimic an acute coronary syndrome in both electrocardiographic appearance and clinical presentation;<ul><li>the differential diagnosis for ST segment elevation on the ECG includes 5:<ul>
+<li>
+<a title="Myocarditis" href="/articles/myocarditis">myocarditis</a> and/or <a title="Pericarditis" href="/articles/pericarditis">pericarditis</a>
+</li>
+<li><a title="Left ventricular enlargement" href="/articles/left-ventricular-enlargement">left ventricular hypertrophy</a></li>
+<li><a title="Left ventricular aneurysm" href="/articles/left-ventricular-aneurysm">left ventricular aneurysm</a></li>
+<li><a title="Takotsubo cardiomyopathy" href="/articles/takotsubo-cardiomyopathy">takotsubo cardiomyopathy</a></li>
+<li>electrolyte abnormalities<ul><li>including hyperkalemia and hypercalcemia</li></ul>
+</li>
+<li><a title="Acute pulmonary embolism" href="/articles/pulmonary-embolism">acute pulmonary embolism</a></li>
+<li><a title="coronary vasospasm" href="/articles/coronary-vasospasm">coronary artery vasospasm</a></li>
+<li>acute CNS pathology<ul><li>including <a title="Subarachnoid hemorrhage" href="/articles/subarachnoid-haemorrhage">subarachnoid hemorrhage</a> and <a title="Intracranial hemorrhage" href="/articles/intracranial-haemorrhage">intracranial hemorrhage</a>
+</li></ul>
+</li>
+<li>benign early repolarization</li>
+<li>elevated intraabdominal/intrathoracic pressure<ul><li>critically ill patients with <a title="Free fluid (summary)" href="/articles/free-intraperitoneal-fluid-summary">free fluid</a> and/or air in their thorax/abdominal cavity may, rarely, present with bizarre ECG patterns, including ST segment elevations<ul>
+<li>the "spiked helmet sign" refers to the characteristic appearance of the sharp upstroke of the baseline leading into ST elevation 3
+</li>
+<li>most commonly noted to occur in massive g<a title="gastric dilatation" href="/articles/gastric-dilatation">astric dilatation</a>, <a title="Small bowel obstruction" href="/articles/small-bowel-obstruction">small bowel obstruction</a>, and <a title="Pneumothorax" href="/articles/pneumothorax">pneumothorax</a> 4
+</li>
+</ul>
+</li></ul>
+</li>
+</ul>
+</li></ul>Other causes of acute chest pain which may mimic the presentation of ACS include;<ul>
+<li>thoracic <a title="Aortic dissection" href="/articles/aortic-dissection">aortic dissection</a>
+</li>
+<li><a title="Esophageal rupture" href="/articles/oesophageal-perforation">esophageal rupture</a></li>
+<li>pulmonary embolism</li>
+<li>pneumothorax</li>
+<li><a title="Cardiac tamponade" href="/articles/cardiac-tamponade">cardiac tamponade</a></li>
+</ul>

References changed:

3. Littmann L & Monroe M. The "Spiked Helmet" Sign: A New Electrocardiographic Marker of Critical Illness and High Risk of Death. Mayo Clin Proc. 2011;86(12):1245-6. <a href="https://doi.org/10.4065/mcp.2011.0647">doi:10.4065/mcp.2011.0647</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/22134944">Pubmed</a>
4. Tomcsányi J, Frész T, Proctor P, Littmann L. Emergence and Resolution of the Electrocardiographic Spiked Helmet Sign in Acute Noncardiac Conditions. Am J Emerg Med. 2015;33(1):127.e5-7. <a href="https://doi.org/10.1016/j.ajem.2014.06.023">doi:10.1016/j.ajem.2014.06.023</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/25066910">Pubmed</a>
5. Judith Tintinalli, J. Stapczynski, O. John Ma et al. Tintinalli's Emergency Medicine: A Comprehensive Study Guide, Seventh Edition. (2010) ISBN: 9780071770064 - <a href="http://books.google.com/books?vid=ISBN9780071770064">Google Books</a>

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