Differential Diagnosis for a Male with Shortness of Breath and Ejection Systolic Murmur

• Single most likely diagnosis:
  • Mitral Regurgitation (MR) - The presence of an ejection systolic murmur that does not radiate, combined with left atrial enlargement on echo, strongly suggests MR. The murmur of MR is typically a holosystolic or late systolic murmur but can be mistaken for an ejection systolic murmur in some cases, especially if the regurgitation is mild or if there's concurrent aortic stenosis. However, the key finding of left atrial enlargement points towards a condition that increases volume load on the left atrium, such as MR.
• Other Likely diagnoses:
  • Aortic Stenosis (AS) - While AS typically presents with a radiating murmur, the severity and characteristics of the murmur can vary. However, AS would more commonly be associated with left ventricular hypertrophy rather than isolated left atrial enlargement.
  • Left Ventricular Hypertrophy - This can be a consequence of various conditions, including hypertension, AS, or other cardiomyopathies. It might not directly explain the left atrial enlargement unless there's associated diastolic dysfunction or other valvular issues.
• Do Not Miss diagnoses:
  • Cardiac Amyloidosis - Although less common, cardiac amyloidosis can present with shortness of breath, murmurs, and left atrial enlargement. It's a condition that would be critical to diagnose due to its implications for treatment and prognosis.
  • Restrictive Cardiomyopathy - This condition can mimic constrictive pericarditis and presents with symptoms of heart failure. It might not directly cause an ejection systolic murmur but could lead to murmurs due to associated mitral or tricuspid regurgitation.
• Rare diagnoses:
  • Cardiac Tumors - Such as atrial myxomas, which can cause obstructive symptoms and murmurs, along with left atrial enlargement.
  • Cor Triatriatum - A rare congenital anomaly where the left atrium is divided into two chambers, potentially leading to obstructive symptoms and left atrial enlargement.

Given the options provided in the question, A. AS is less likely to be the correct answer because it typically radiates and is associated with left ventricular hypertrophy rather than isolated left atrial enlargement. B. Left Ventricular Hypertrophy might be present but does not directly explain the clinical findings as well as other diagnoses like Mitral Regurgitation. Therefore, neither of the provided options perfectly matches the most likely diagnosis based on the clinical scenario described.