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Low-Gradient AS Diagnosis — RACP Adult Medicine MCQ

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HardCardiologyLow-Gradient AS DiagnosisRACP Adult Medicine

A 70-year-old with LVEF 30% has aortic valve area 0.6 cm2, mean gradient 25 mmHg and low stroke volume. Which test best distinguishes true severe from pseudo-severe low-flow, low-gradient aortic stenosis when contractile reserve is possible?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Use low-dose dobutamine stress echocardiography

The best answer is “Use low-dose dobutamine stress echocardiography”. Low-dose dobutamine increases flow. In true severe stenosis, gradient rises while valve area remains small; in pseudo-severe disease the valve area increases as flow improves. The study also assesses flow reserve. Exercise is unsafe or uninformative in many symptomatic low-flow patients, and repeat resting studies do not resolve flow dependence.

Reference: Heart Foundation: Australian clinical guidelines and position statements: https://www.heartfoundation.org.au/for-professionals/clinical-guidelines-position-statements ACC/AHA: Valvular heart disease guideline: https://www.acc.org/Guidelines/Hubs/Valvular-Heart-Disease