A 55-year-old man presents to the emergency department with chest pressure and diaphoresis. His symptoms started at work when he was lifting boxes. He states that he currently feels crushing pressure over his chest. He is given aspirin and an ECG is performed in triage, as seen in Figure A. His past medical history is notable for diabetes and obesity. He has smoked 1 pack of cigarettes per day for the past 30 years. His temperature is 97.9°F (36.6°C), blood pressure is 155/99 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 98% on room air. Physical exam reveals an uncomfortable, diaphoretic man. His heart and breath sounds are unremarkable. A repeat ECG in the emergency department is performed, also seen in Figure A. The patient’s chest pain is worse when the ECG in the emergency department is taken, compared to the one taken in triage. He is given nitroglycerin, with minimal improvement in his symptoms. A troponin level is drawn. Which of the following is the most appropriate next step in management?
Repeat ECG in 10 minutes
Cardiac catheterization
Heparin
Chest radiograph
Repeat ECG in 10 minutes
This patient is presenting with a pattern of chest pain (pressure and diaphoresis) that is highly concerning for an acute myocardial infarction. This patient initially has ST depressions (in triage) followed by ST segment normalization and possibly hyperacute T waves which raises concern for an acute ST elevation myocardial infarction (STEMI) requiring frequent ECGs to determine if a STEMI evolves.

A STEMI presents with crushing substernal chest pain, diaphoresis, chest pressure, nausea, vomiting, and abdominal pain among many other possible presentations. When a patient presents with symptoms concerning for a STEMI, aspirin should be administered and an ECG should be performed. Early in a myocardial infarction, ST depressions with hyperacute T waves may be present. As the infarction evolves, the T waves may become more acute and the ST segment will begin to elevate. There may be a brief period of pseudonormalization where the ST segment appears to be normal. If the patient appears better, this can be reassuring. However, ongoing chest pain in the setting of these findings raises concern for pseudonormalization of the ST segment (an ST segment that is going to continue to rise). Nitroglycerin can be administered to see if the patient can become chest pain-free, and serial ECGs should be performed to determine if a STEMI is present. If symptoms resolve and the ECG is stable, this is reassuring and medical optimization and an elective catheterization may be performed. If the ECG evolves into a STEMI, then cardiac catheterization is indicated emergently.

Daga et al. discuss STEMI and its workup. They note the ECG manifestations, and the pathophysiology in addition to the appropriate workup of acute coronary syndrome. They recommend aspirin and catheterization in an acute STEMI.

Figure/Illustration A demonstrates an initial ECG with ST depression (blue arrows) followed by pseudonormalization of the ST segment (green arrows) and possibly hyperacute T waves (black arrows), which are concerning for ischemia.

Incorrect Answers:
Answer A: Cardiac catheterization may be required in this patient; however, if the patient’s chest pain improves or if the troponin is negative, it is unlikely he is having an acute myocardial infarction requiring immediate catheterization. Repeating the ECG will allow for triaging of the patient and will aid in determining if emergency cardiac catheterization is needed.

Answer B: Chest radiography is appropriate in the workup of chest pain as it can rule out diagnoses such as pneumothorax or may suggest diagnoses such as an aortic dissection (type A) if there is a widened mediastinum. In this patient, the ST segment changes and characteristic history make acute coronary syndrome a more likely diagnosis, and while a chest radiograph should be performed at some point, repeating the ECG is a more dire initial step in management.

Answer C: CK-MB level could be helpful in determining if a myocardial infarction has occurred as it elevates rapidly and also decreases fairly rapidly. This makes it useful when diagnosing a new myocardial infarction after a recent infarction as the troponin may still be elevated from the previous infarction. This patient has no history of recent myocardial infarction, and a repeat ECG is more dire to determine if this patient needs emergent intervention. Of note, the decision for emergent catheterization should not wait on cardiac biomarkers.

Answer D: Heparin should not be given empirically to patients in chest pain. It does not necessarily decrease mortality but does increase the risk of bleeding. It is often given to patients with an NSTEMI.

Bullet Summary:
Pseudonormalization occurs when an ST depression begins to elevate and appears normal in the setting of a myocardial infarction, requiring close monitoring and serial ECGs to ensure that a ST elevation myocardial infarction does not occur.