A 72-year-old man presents with progressive exertional dyspnea, occasional dizziness, and a crescendo-decrescendo systolic murmur best heard at the right upper sternal border radiating to the carotids. A delayed carotid upstroke is noted on examination. Which of the following is the most appropriate initial diagnostic test to confirm the diagnosis and assess severity?

The correct answer to the question "A 72-year-old man presents with progressive exertional dyspnea, occasional dizziness, and a crescendo-decrescendo systolic murmur best heard at the right upper sternal border radiating to the carotids. A delayed carotid upstroke is noted on examination. Which of the following is the most appropriate initial diagnostic test to confirm the diagnosis and assess severity?" is Option C: Transthoracic Echocardiogram (TTE).

The other options — A) Electrocardiogram (ECG), B) Chest X-ray, D) Cardiac Catheterization — are incorrect for this USMLE Exam Prep question. As explained above: The clinical presentation is highly suggestive of aortic stenosis. TTE is the gold standard for diagnosis, assessing valve morphology, transvalvular gradients, and left ventricular function.