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.
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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
Etiology
The most common cause by far is atherosclerotic plaque rupture in coronary artery disease. Other less common causes include:
connective tissue diseases
drugs: cocaine
Unusual variants:
Kounis syndrome: allergic/hypersensitivity precipitant
Differential diagnosis
Several other pathological entities may mimic an acute coronary syndrome in both electrocardiographic appearance and clinical presentation;
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the differential diagnosis for ST segment elevation on the ECG includes 5:
myocarditis and/or pericarditis
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electrolyte abnormalities
including hyperkalemia and hypercalcemia
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acute CNS pathology
including subarachnoid hemorrhage and intracranial hemorrhage
benign early repolarization
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elevated intraabdominal/intrathoracic pressure
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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 pneumothorax 4
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Other serious causes of acute chest pain which may mimic the presentation of ACS include;
thoracic aortic dissection
pulmonary embolism
pneumothorax
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