majority of cases of aortic dissection, the12‐lead ECG will be abnormal, but will not show ST‐segment elevation unless the origin of a coronary artery is occluded by the dissection [74]. Without imaging capability that exists in the hospital, EMS clinicians may suspect, but cannot identify, aortic dissection definitively [75, 76]. If aortic dissection is suspected, morphine can be used for pain control but aspirin should be avoided, since patients with acute aortic syndrome who receive antithrombotic agents such as aspirin or fibrinolytics are more likely to bleed [77].
Pericarditis
Individuals with pericarditis may present to EMS with ST‐segment elevation on an ECG that looks similar to an extensive myocardial infarction. Administration of fibrinolytics in this condition may be fatal because these patients can bleed into the pericardial sac, resulting in pericardial tamponade. Aspirin administration is somewhat less concerning because anti‐inflammatory medications are part of the recommended treatment.
Pneumothorax
A pneumothorax may cause chest pain, shortness of breath, hypoxia, and diaphoresis. Clinical signs may point more to this diagnosis than to acute myocardial infarction. EMS systems should have a separate protocol for management of a pneumothorax. Oxygen and morphine may help the patient. Nitroglycerin should be avoided because it can cause hypotension by further decreasing venous return if the patient is developing a tension pneumothorax. If a developing tension pneumothorax is evident, needle decompression is required.
Pulmonary Embolism
Pulmonary embolism is a great masquerader because its symptoms may be similar to those of other causes of chest pain and shortness of breath. Its presentation can easily be confused with myocardial infarction or anxiety. Treatment should focus on maximizing oxygenation to the patient. If pulmonary embolism is suspected, nitroglycerin should be avoided because it can cause significant hypotension. Administration of fibrinolytics may potentially benefit the patient, but it is preferable to delay administration until the patient has reached a hospital and undergone definitive diagnostic imaging.
Esophageal Perforation
A patient with a perforated esophagus may present with chest pain. A careful and focused history and examination will often help differentiate this condition from other causes of chest pain. Nitroglycerin should be avoided because it may cause significant hypotension, and fibrinolytics are contraindicated because of the need for immediate surgery.
Summary
Quality prehospital care of patients with chest pain can relieve discomfort and improve outcome. EMS systems should have the capability to perform prehospital 12‐lead ECGs, and regional protocols should focus on delivering patients with STEMI to PCI centers promptly. Prehospital activation of the cardiac catheterization laboratory is highly effective at shortening the time to definitive reperfusion treatment and should be encouraged.
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