Differential Diagnosis for the 74-year-old Woman with Chest Pain and Respiratory Distress

Single Most Likely Diagnosis

• Cardiogenic Shock due to Acute Myocardial Infarction (MI): The patient's presentation with chest pain, hyperacute T waves in the lateral leads on ECG, and a history of ischemic cardiomyopathy strongly suggests an acute MI. The signs of shock (hypotension, tachycardia, cool and mottled extremities) and respiratory distress (rales, low SpO2) are consistent with cardiogenic shock, where the heart is unable to pump enough blood to meet the body's needs, often due to extensive myocardial damage.

Other Likely Diagnoses

• Pulmonary Edema: The presence of rales bilaterally and pitting edema, along with the patient's history of ischemic cardiomyopathy, suggests possible pulmonary edema, which could be contributing to her respiratory distress. This could be due to heart failure exacerbation or acute MI.
• Acute Heart Failure: Given the patient's history and symptoms, acute heart failure is a likely diagnosis. The heart's inability to pump blood effectively can lead to fluid buildup in the lungs (causing respiratory distress) and peripheral tissues (causing edema).

Do Not Miss Diagnoses

• Pulmonary Embolism (PE): Although less likely given the ECG findings suggestive of MI, PE can cause sudden onset of chest pain, respiratory distress, and shock. It's crucial to consider PE due to its high mortality rate if untreated.
• Aortic Dissection: This is a life-threatening condition that can cause chest pain and shock. Although the ECG suggests MI, aortic dissection can sometimes present with ECG changes mimicking MI, especially if the dissection involves the coronary arteries.

Rare Diagnoses

• Stress-Induced Cardiomyopathy (Takotsubo Cardiomyopathy): This condition can mimic acute MI and heart failure, causing chest pain, respiratory distress, and signs of cardiogenic shock. It's often triggered by intense emotional or physical stress.
• Cardiac Tamponade: Although less likely without specific signs like pulsus paradoxus mentioned, cardiac tamponade can cause shock and respiratory distress. It would be more likely if there were signs of cardiac chamber compression on imaging.

The expected ultrasound finding based on the likely etiology of shock (cardiogenic shock due to acute MI) would be Elevated E-point septal separation, indicating left ventricular dysfunction, which is consistent with cardiogenic shock.