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Dobutamine Stress Echo in Low-flow AS — EECC MCQ

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HardCardiac ImagingDobutamine Stress Echo in Low-flow ASEECC

A 72-year-old woman with low-flow low-gradient aortic stenosis (LVEF 32%, AVA 0.8 cm², mean gradient 25 mmHg) undergoes dobutamine stress echocardiography. At peak dobutamine, her stroke volume increases by 20% and the mean gradient rises to 45 mmHg while AVA remains 0.8 cm². What does this indicate?

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Correct answer: C — True severe AS with contractile reserve — the increase in flow (stroke volume) unmasks the true severity (gradient rises, AVA remains small); this patient will benefit from AVR

Low-dose dobutamine stress echocardiography is the key investigation for classical low-flow low-gradient AS (LVEF <50%, gradient <40 mmHg, AVA ≤1.0 cm²). It differentiates: (1) True severe AS with contractile reserve (this case): stroke volume increases (≥20% = contractile reserve present), gradient rises (confirming fixed obstruction), AVA remains ≤1.0 cm² — patient benefits from AVR; (2) Pseudo-severe AS: stroke volume increases, gradient rises modestly, AVA increases >1.0 cm² — the valve was opening suboptimally due to low output, not true stenosis — AVR not beneficial; (3) No contractile reserve: stroke volume does not increase — true severity cannot be determined; CT aortic valve calcium scoring becomes crucial (>2000 AU men = likely severe). The 2025 ESC VHD Guidelines recommend dobutamine stress echo for all low-flow low-gradient AS cases.

Reference: ESC/EACTS (2025): VHD Guidelines