American Board of Internal Medicine (ABIM) Certification Practice Exam

What mean gradient value qualifies for very severe aortic stenosis?

1. Less than 20 mm Hg

2. 20-39 mm Hg

3. 40-59 mm Hg

4. 60 mm Hg or greater

The correct answer is: 60 mm Hg or greater

Very severe aortic stenosis is characterized by significant obstruction to left ventricular outflow, which is reflected in the mean gradient across the aortic valve. A mean gradient of 60 mm Hg or greater indicates a high level of pressure difference between the left ventricle and the aorta during systole, suggesting that the aortic valve is severely narrowed. To provide context, this high mean gradient correlates with symptomatic severe aortic stenosis and a need for surgical intervention. This level of obstruction typically leads to pronounced left ventricular hypertrophy, decreased cardiac output during exertion, and significant cardiovascular strain. In contrast, a mean gradient of less than 20 mm Hg would usually suggest mild aortic stenosis, while gradients between 20-39 mm Hg and 40-59 mm Hg denote moderate to severe stenosis, but do not reach the threshold that indicates very severe aortic stenosis. This threshold is critical for making clinical decisions regarding the timing and type of intervention required, such as valve replacement.