Differential Diagnosis

The patient presents with tachycardia, a temperature of 38°C, and an otherwise normal physical exam except for the ECG findings. Given the information, here is a structured differential diagnosis:

• Single Most Likely Diagnosis

  • Viral Pericarditis: This condition is characterized by inflammation of the pericardium, often due to viral infections. The patient's fever and tachycardia, along with the pending ECG and troponin results, could support this diagnosis, especially if the ECG shows signs suggestive of pericarditis such as widespread ST elevation.

• Other Likely Diagnoses

  • Viral Myopericarditis: Similar to viral pericarditis but involves both the myocardium and pericardium. The presence of fever and tachycardia, with potential ECG changes and pending troponin levels, makes this a plausible diagnosis.
  • Acute Coronary Syndrome (ACS): Although less likely given the patient's age and the fact that oxygen saturation is normal, ACS cannot be ruled out without further investigation, including the troponin level and detailed ECG analysis.
  • Pneumonia: The fever and tachycardia could also suggest a respiratory infection like pneumonia, especially if the patient has other symptoms such as cough or chest pain.

• Do Not Miss Diagnoses

  • Pulmonary Embolism (PE): Although the oxygen saturation is normal, PE is a critical diagnosis that must be considered, especially if there are any signs of respiratory distress or if the ECG shows signs suggestive of PE, such as the S1Q3T3 pattern.
  • Cardiac Tamponade: A life-threatening condition that could result from pericarditis or other causes. It would typically present with hypotension, muffled heart sounds, and possibly pulsus paradoxus, which are not mentioned but should be considered.
  • Aortic Dissection: A catastrophic condition that requires immediate diagnosis and treatment. It might present with chest pain and differential blood pressures in the arms, neither of which is mentioned, but it's crucial not to miss.

• Rare Diagnoses

  • Myocarditis: An inflammation of the myocardium that can present with fever, tachycardia, and ECG changes. It's less common but should be considered, especially if viral serologies are positive or if there's evidence of myocardial involvement on imaging or biopsy.
  • Stress Cardiomyopathy (Takotsubo Cardiomyopathy): A condition that mimics ACS but is caused by extreme emotional or physical stress. It's rare and typically presents in post-menopausal women with deep emotional stress, but it's an important differential in the appropriate context.