Differential Diagnosis for the Patient's Condition

The patient presents with dyspnea, a history of prolonged substernal chest pain, and specific findings on physical examination and EKG. Based on these symptoms and signs, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Acute Myocardial Infarction (MI) with Mitral Regurgitation: The patient's history of prolonged substernal chest pain is highly suggestive of an acute myocardial infarction. The presence of a systolic murmur at the apex, indicative of mitral regurgitation, could be a complication of the MI, particularly if the infarction involved the papillary muscles. The EKG findings, including negative QRS complexes in leads aVR, V1, V2, and V3, and positive QRS deflections in leads I and II, suggest an inferior wall MI, which can lead to mitral regurgitation due to papillary muscle dysfunction.

• Other Likely Diagnoses

  • Pulmonary Embolism: Although less likely given the chest pain history and EKG changes, pulmonary embolism could explain dyspnea, tachypnea, and hypoxia. The presence of crackles on lung examination could be due to pulmonary infarction.
  • Heart Failure: The patient's symptoms of dyspnea, crackles on lung examination, and hypoxia could be indicative of heart failure, potentially as a consequence of the myocardial infarction or another cardiac condition.

• Do Not Miss Diagnoses

  • Aortic Dissection: Although the presentation is not classic (e.g., tearing chest pain), aortic dissection is a life-threatening condition that must be considered, especially with severe chest pain and hypertension. The absence of typical symptoms does not rule out this diagnosis.
  • Cardiac Tamponade: This condition, which can result from myocardial infarction or aortic dissection, presents with hypotension, muffled heart sounds, and pulsus paradoxus. While not all these signs are present, the potential for cardiac tamponade to develop rapidly makes it a critical diagnosis not to miss.

• Rare Diagnoses

  • Stress-Induced Cardiomyopathy (Takotsubo Cardiomyopathy): This condition mimics acute myocardial infarction but is caused by extreme emotional or physical stress. It could explain the chest pain and EKG changes but would be less likely given the specific EKG pattern described.
  • Coronary Artery Dissection: A rare cause of myocardial infarction, especially in women, which could present similarly to a traditional MI but might have a different management approach.