Aortic stenosis
Concordant or discordant grading, flow and calcium, cardiac damage — and when an asymptomatic patient needs a valve.
Numbers to remember
- Severe: Vmax ≥4.0 m/s, mean gradient ≥40 mmHg, AVA <1.0 cm² (AVAi <0.6 cm²/m²), DVI <0.25 [5,6,7]
- Low flow: SVi <35 mL/m² [5]
- Calcium score (CT): severe likely at ≥2000 AU men / ≥1200 AU women [5,172]
- Very severe: Vmax ≥5 m/s or rapid progression ≥0.3 m/s/year [6,60]
- Zva ≥4.5 mmHg/mL/m² = high global afterload [158]
Questions echo must answer
Aortic stenosis is graded by velocity, gradient and valve area. The difficulty is discordance (a small area with a low gradient), which is resolved by measuring flow and calcium [5,172]. Timing is shifting towards earlier intervention: three randomised trials showed benefit of early AVR in asymptomatic severe AS [61,62,63].
- SeverityVmax, mean gradient, AVA by continuity and DVI [5].
- Concordant or discordant?If discordant, what is the flow (SVi) and the LVEF? [5]
- MorphologyTricuspid, bicuspid or rheumatic; calcification; aortic dimensions [5,9].
- Cardiac damageLV hypertrophy, GLS, LVEF, LA, PH, TR and RV — the Généreux stages [58,103,187].
- Global loadValvulo-arterial impedance, hypertension [113,158].
Acquisition protocol
- PLAX zoomLVOT diameter in mid-systole, inner edge to inner edge, at the annulus or 0.5–1 cm below — the same level as the PW sample [5].
- A5C / A3C PWLVOT VTI with the sample just proximal to the flow acceleration (a clean envelope with a closing click) [5].
- Multi-window CWApical, right parasternal, suprasternal and subcostal. Use a dedicated pencil probe. Record the highest clean envelope [5].
- DerivedAVA = LVOT area × VTI-LVOT / VTI-AV; DVI = VTI-LVOT / VTI-AV; SVi [5,79].
- MorphologyPSAX in systole for cusp number and a raphe; calcification grade.
- LVWall thickness, mass, LVEF, GLS [187].
- AortaRoot and ascending aorta (bicuspid aortopathy) [9].
- ConsequencesLAVI, E/e′, TR velocity, TAPSE [58].
- BPRecord blood pressure at the time of the study (for Zva) [158].
- LVOT diameter and PW VTI (same level)
- Vmax and MG (window __)
- AVA, AVAi, DVI
- SVi (flow)
- Morphology and calcification
- LVEF, GLS, LV mass
- Aortic dimensions
- Cardiac damage stage
- BP recorded; Zva
Diagnosis & severity
| Aortic sclerosis | Mild | Moderate | Severe | |
|---|---|---|---|---|
| Vmax (m/s) | ≤2.5 | 2.6–2.9 | 3.0–3.9 | ≥4.0 |
| Mean gradient (mmHg) | — | <20 | 20–39 | ≥40 |
| AVA (cm²) | — | >1.5 | 1.0–1.5 | <1.0 |
| AVAi (cm²/m²) | — | >0.85 | 0.60–0.85 | <0.6 |
| DVI | — | >0.50 | 0.25–0.50 | <0.25 |
Source: EACVI/ASE [5].
Discordant grading (AVA <1.0 cm² but MG <40 mmHg) [5,6]
| Pattern | Definition | Next step |
|---|---|---|
| Classical low-flow low-gradient | LVEF <50%, SVi <35 | Low-dose dobutamine: true severe if MG ≥40 with AVA ≤1.0; flow reserve if SV rises ≥20% |
| Paradoxical low-flow low-gradient | LVEF ≥50%, SVi <35 | Re-check measurements; CT calcium score |
| Normal-flow low-gradient | LVEF ≥50%, SVi ≥35 | Usually moderate AS or measurement error |
Staging cardiac damage [58,103]
Stage 0: no damage. Stage 1: LV damage (LVH, EF <60%, E/e′ >14). Stage 2: LA or mitral damage (LAVI >34, AF, moderate–severe MR). Stage 3: pulmonary vasculature or tricuspid damage (PASP ≥60, moderate–severe TR). Stage 4: RV dysfunction. Each stage increases mortality after AVR.
Thresholds that change management
- Symptomatic severe AS (high-gradient, or low-flow confirmed) → AVR. Choose TAVI or SAVR according to age, anatomy and surgical risk in the Heart Team [6,7].
- Asymptomatic severe AS with LVEF <50% → AVR [6,7].
- Asymptomatic severe AS with LVEF ≥50% → early intervention reduced events in RECOVERY (very severe AS), AVATAR and EARLY TAVR. The 2025 ESC/EACTS guideline supports considering early intervention in selected low-risk patients [6,61,62,63].
- Markers favouring early intervention: Vmax ≥5 m/s, rapid progression ≥0.3 m/s/year with heavy calcification, symptoms or a fall in BP on exercise testing, markedly raised BNP, reduced GLS [6,60,187].
- Moderate AS with LV dysfunction is associated with high risk. It is being tested in trials and is not yet an indication by itself [6].
Pitfalls & mimics
PitfallThe LVOT diameter is squared. A 1 mm error changes the AVA by about 10%. The LVOT is often elliptical, so the AVA is underestimated. When the numbers disagree, trust the DVI and the calcium score [5,172].
- Doppler misalignment underestimates. Always use multiple windows, including the right parasternal [5].
- Contamination by an MR jet creates an apparently high "AS" velocity. The MR jet begins earlier (isovolumic contraction) and lasts longer.
- Pressure recovery in a small ascending aorta (<30 mm) makes Doppler overestimate the gradient [5].
- Hypertension at the time of the study lowers the gradient. Repeat when BP is controlled [5].
- Atrial fibrillation: average 5 beats; avoid post-extrasystolic beats.
- Subvalvular or supravalvular obstruction and dynamic LVOTO (HCM) mimic valvular AS.