Aortic stenosis vs Hypertrophic cardiomyopathy
How to tell Aortic stenosis and Hypertrophic cardiomyopathy apart when a board question makes them look alike.
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Murmur response to Valsalva maneuver.
Side by side
Older patient with exertional syncope and harsh crescendo-decrescendo murmur radiating to the carotids suggests aortic stenosis.
Younger patient with exertional symptoms and systolic murmur that intensifies with Valsalva suggests hypertrophic cardiomyopathy.
Fixed valvular outflow obstruction from calcific narrowing limits stroke volume during exertion.
Dynamic left ventricular outflow obstruction from septal hypertrophy worsens when preload falls.
Echocardiography shows aortic valve area 1.0 cm2 or less and mean gradient 40 mm Hg or higher in severe disease.
Echocardiography shows asymmetric septal hypertrophy, often septal thickness 15 mm or greater, with dynamic LVOT gradient that increases with provocation.
The trap
Both can present with exertional syncope and systolic murmur, but Valsalva decreases preload and usually softens fixed AS while intensifying dynamic HCM obstruction.
The repair move
Next best step: obtain transthoracic echocardiography to define fixed versus dynamic obstruction, then refer severe symptomatic aortic stenosis for valve replacement or treat obstructive HCM with nonvasodilating beta-blocker and activity counseling.
Try a free question
CoreA 24-year-old athlete has exertional presyncope and a systolic murmur that increases with Valsalva. What is the most likely diagnosis?
Show answer and explanation
Answer: B. Hypertrophic cardiomyopathy. Murmur augmentation with Valsalva in a young patient is characteristic of hypertrophic cardiomyopathy.
Why the other choices are tempting
- A. Incorrect because fixed aortic stenosis typically softens or does not intensify with Valsalva.
- C. Incorrect because mitral regurgitation has a holosystolic blowing murmur at the apex.
- D. Incorrect because ASD classically has fixed split S2 rather than this maneuver-dependent murmur.
- E. Incorrect because pulmonic stenosis has left upper sternal border findings and different radiation pattern.
Flashcards
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How does Valsalva affect the systolic murmur in hypertrophic cardiomyopathy?
It typically becomes louder because reduced preload worsens dynamic outflow obstruction.
What auscultation feature strongly supports aortic stenosis over HCM?
Harsh crescendo-decrescendo murmur radiating to the carotids.
Quick answers
What is the fastest way to tell Aortic stenosis from Hypertrophic cardiomyopathy?
Murmur response to Valsalva maneuver.
What is the key clue for Aortic stenosis?
Older patient with exertional syncope and harsh crescendo-decrescendo murmur radiating to the carotids suggests aortic stenosis.
What is the key clue for Hypertrophic cardiomyopathy?
Younger patient with exertional symptoms and systolic murmur that intensifies with Valsalva suggests hypertrophic cardiomyopathy.
What is the common trap with Aortic stenosis vs Hypertrophic cardiomyopathy?
Both can present with exertional syncope and systolic murmur, but Valsalva decreases preload and usually softens fixed AS while intensifying dynamic HCM obstruction.