Paradoxical LFLG AS with Preserved EF — EECC MCQ

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HardHeart FailureParadoxical LFLG AS with Preserved EFEECC

A 70-year-old man with HFpEF has severe aortic stenosis. His echocardiographer notes that the indexed stroke volume is 28 mL/m² (low flow). The mean gradient is 35 mmHg and AVA is 0.8 cm². What condition is this?

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Correct answer: A — Paradoxical low-flow, low-gradient severe AS with preserved LVEF — despite normal LVEF, the stroke volume is low (SVi <35 mL/m²) due to concentric LVH/small LV cavity, causing misleadingly low gradients; CT aortic valve calcium scoring is essential for confirming true severity

Paradoxical low-flow, low-gradient (LFLG) severe AS with preserved LVEF is a challenging diagnostic entity: (1) LVEF is ≥50% (normal); (2) SVi is <35 mL/m² (low — due to concentric LVH causing a small LV cavity with reduced stroke volume despite normal EF); (3) mean gradient is <40 mmHg (misleadingly low due to reduced transvalvular flow); (4) AVA is ≤1.0 cm² (may reflect true severe AS or be falsely low from measurement error). Diagnosis requires: (1) CT aortic valve calcium scoring — the most important test: >2,000 AU men, >1,200 AU women confirms severe AS regardless of gradient; (2) exclude measurement errors (LVOT diameter); (3) assess for other causes of low SVi (HFpEF, significant MR). The 2025 ESC VHD Guidelines recommend CT calcium scoring as the primary tool for resolving this diagnostic dilemma.

Reference: ESC/EACTS (2025): VHD Guidelines