Echo Reference — Valve Stenosis
Mitral Stenosis Severity Grading on Echocardiography and MVA Calculator
Severity thresholds for mitral valve area, mean gradient, pressure half-time and pulmonary pressure in rheumatic mitral stenosis — with MVA calculators by pressure half-time and continuity equation, how each measurement is acquired and where it fails, rheumatic versus calcific disease, discordant findings, and the Wilkins score for balloon commissurotomy.
Severity Grading
| Parameter | Mild | Moderate | Severe |
|---|---|---|---|
| Mitral valve area (cm²) | > 2.5 | 1.6 – 2.5 | ≤ 1.5 |
| Pressure half-time (ms) | < 100 | 100 – 149 | ≥ 150 |
| Mean gradient (mmHg)* | < 5 | 5 – 9 | ≥ 10 |
| PASP (mmHg) | < 30 | 30 – 49 | ≥ 50 |
Rheumatic mitral stenosis. Source: ASE 2023 recommendations for echocardiography in rheumatic heart disease, Table 1 [1]. *At a heart rate of 60–80 bpm; gradients rise with tachycardia, exercise, pregnancy and other high-output states.
Thresholds Across References
Valve area categories differ between documents, which is the usual reason two reports grade the same valve differently.
| Reference | Valve area categories |
|---|---|
| ASE 2023 (table above) [1] | Mild > 2.5 cm² · Moderate 1.6–2.5 cm² · Severe ≤ 1.5 cm² |
| ACC/AHA 2020 [3] | Progressive > 1.5 cm² (PHT < 150 ms) · Severe ≤ 1.5 cm² (PHT ≥ 150 ms) |
| ESC/EACTS 2025 [4] | Clinically severe ≤ 1.5 cm² |
| EAE/ASE 2009 — superseded [2] | Mild > 1.5 cm² · Moderate 1.0–1.5 cm² · Severe < 1.0 cm² |
The 2009 categories are no longer current: ASE now directs readers to the ACC/AHA staging and to its 2023 document. A report describing a valve area of 1.2 cm² as moderate is using the superseded scale.
The table applies to rheumatic disease. Calcific mitral stenosis narrows the valve at a different level and needs a different approach — see rheumatic versus calcific mitral stenosis.
MVA Calculator — Pressure Half-Time and Continuity Equation
Two Doppler estimates of mitral valve area. Each is a single-method estimate, to be read alongside planimetry, the gradient at the recorded heart rate, PASP and valve morphology.
MVA by Pressure Half-Time
MVA = 220 ÷ PHT. Gradient, heart rate and rhythm are optional; they add context to the result and to the report line.
Category is the PHT-derived area set against the ASE 2023 rheumatic bands. It is one method's estimate, not an overall severity grade.
How Pressure Half-Time Is Measured
Pressure half-time is the time taken for the peak transmitral pressure gradient to fall by half. Because pressure varies with the square of velocity, that point is where velocity has fallen to peak ÷ √2 — about 71% of peak — and not to half the peak velocity. On a linear slope, PHT = 0.29 × deceleration time.
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MVA by Continuity Equation
MVA = (LVOT area × LVOT VTI) ÷ mitral VTI. Valid only in a regular rhythm, not atrial fibrillation, and with no more than mild mitral or aortic regurgitation.
Category is the continuity-derived area set against the ASE 2023 rheumatic bands. It is one method's estimate, not an overall severity grade.
How Mitral Valve Area Is Measured
Planimetry measures the orifice directly. The Doppler methods infer it from flow and each depends on conditions that are often not met in practice.
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| Method | Technique | Strengths and limits |
|---|---|---|
| 2D planimetry | Parasternal short axis. The plane is swept from apex to base to find the leaflet tips — the smallest orifice in space — and the inner edge is traced, including any open commissure, on the frame of maximal opening in mid-diastole. Zoom mode, cine-loop review, and gain just sufficient to show the whole contour. | Reference method; largely independent of flow, heart rate and chamber compliance. Overestimates when the plane is oblique or basal to the tips; excess gain underestimates. Difficult with heavy calcification, poor windows, or an irregular orifice after commissurotomy. |
| 3D planimetry | Multiplanar reconstruction from a 3D dataset (transthoracic or transoesophageal), with the cropping plane aligned to the leaflet tips in two orthogonal long-axis views. | Reduces the plane-position error of 2D and is preferred when available. Needs adequate image quality; spatial and temporal resolution are lower than 2D. |
| Pressure half-time | MVA = 220 ÷ PHT. CW Doppler through the mitral orifice, tracing the E-wave deceleration slope. With a bimodal slope, the mid-diastolic slope is traced rather than the early steep segment. In atrial fibrillation, short diastoles are avoided and several cycles averaged. | Quick and widely available. Depends on net atrioventricular compliance and the starting gradient as well as valve area — see sources of error. Tends to overestimate area in calcific disease. |
| Continuity equation | MVA = (LVOT area × LVOT VTI) ÷ mitral VTI, with the mitral VTI from CW Doppler. | Useful when planimetry and PHT are unreliable. Not valid in atrial fibrillation or with significant regurgitation: mitral regurgitation makes the calculated area too small, aortic regurgitation makes it too large. Any error in LVOT diameter is squared. |
| PISA | MVA = 2πr² × aliasing velocity ÷ peak mitral velocity × (α ÷ 180), where r is the radius of the convergence zone on the atrial side and α the opening angle of the leaflets. | Can be used when mitral regurgitation is significant. Technically demanding, with several measurements each contributing error. |
Techniques follow the EAE/ASE valve stenosis recommendations [2] and the ASE 2023 rheumatic heart disease document [1].
Gradient, Heart Rate and Flow
The mean gradient is traced from the CW Doppler mitral inflow envelope, with the beam aligned to the jet under colour Doppler guidance. It rises with heart rate and with flow: a patient with a valve area of 1.2 cm² can have a mean gradient below 5 mmHg at 65 bpm and above 15 mmHg at 110 bpm or during exercise. Heart rate and rhythm belong beside every reported gradient; without them, interpretation is limited.
Measurement Pitfalls
Pressure Half-Time — Sources of Error
Half-time is governed by valve area, by the gradient at the start of diastole, and by the net compliance of the left atrium and left ventricle together. When compliance or the starting gradient is unusual, 220 ÷ PHT no longer tracks area.
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| Situation | Effect on PHT | Effect on the MVA estimate |
|---|---|---|
| Significant aortic regurgitation | Shortened — LV diastolic pressure rises faster | Overestimated; stenosis understated |
| Reduced LV compliance (hypertrophy, restrictive filling, older age) | Shortened | Overestimated |
| Atrial septal defect | Shortened — the left atrium decompresses through the defect | Overestimated |
| Increased net atrioventricular compliance | Prolonged | Underestimated; stenosis overstated |
| Early after balloon commissurotomy | Unreliable for days to weeks — the gradient falls abruptly while net compliance is still changing | Error in either direction; planimetry is used instead, by 3D where available |
| Bimodal deceleration slope | Too short if the early steep segment is traced | Overestimated; the mid-diastolic slope is the one to trace |
| Half velocity used in place of peak ÷ √2 | Too long — 0.5 × deceleration time instead of 0.29 × | Underestimated; stenosis overstated |
| Tachycardia, short diastole, E–A fusion | Slope too short to trace reliably | Unreliable; measured at a controlled rate, or on longer cycles in atrial fibrillation |
| Calcific mitral stenosis | Often short relative to the true area | Overestimated — see calcific disease |
The 220 constant is empirical, derived in rheumatic mitral stenosis [5]; the dependence on gradient and compliance was shown immediately after balloon valvotomy [6].
Planimetry, Gradient and Associated Lesions
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| Pitfall | Effect | Approach |
|---|---|---|
| Planimetry plane basal to the leaflet tips | Valve area overestimated | Sweep from apex to base and take the smallest orifice; confirm with 3D |
| Oblique short-axis plane | Valve area overestimated | Check alignment in the long-axis view; biplane or 3D imaging |
| Gain setting | Excess gain narrows the traced orifice and underestimates area; drop-out does the opposite | Gain just sufficient to show the complete contour |
| Frame selection | The orifice varies through diastole; a single frozen frame may not show maximal opening | Cine-loop review; trace maximal opening in mid-diastole |
| CW beam off the inflow jet | Gradient underestimated | Colour-guided alignment from the apical window |
| Gradient reported without heart rate or rhythm | 8 mmHg at 65 bpm and 8 mmHg at 110 bpm require different haemodynamic interpretation | Both recorded with every gradient |
| Atrial fibrillation | Beat-to-beat variation in gradient and half-time | Average of five cycles with the least R–R variation, as close as possible to a normal rate |
| Coexisting mitral regurgitation | Higher transmitral flow and gradient for a given area; continuity-derived area too small | Planimetry; quantify the regurgitation — see mitral regurgitation grading |
| Coexisting aortic regurgitation | Shorter half-time; continuity-derived area too large | Planimetry |
| PASP read as a severity criterion | PASP also reflects pulmonary vascular disease, lung disease and other causes of raised left atrial pressure | Reported as a haemodynamic consequence — see pulmonary haemodynamics |
Rheumatic Versus Calcific Mitral Stenosis
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| Feature | Rheumatic | Calcific (annular calcification) |
|---|---|---|
| Mechanism | Commissural fusion, leaflet-tip thickening, chordal fusion and shortening | Annular calcification extending onto the leaflet bases; commissures typically not fused |
| Narrowest level | Leaflet tips — a funnel-shaped orifice | Annulus and leaflet bases — a tubular inflow; the tips often stay mobile |
| 2D appearance | Diastolic doming of the anterior leaflet with a restricted posterior leaflet | Bulky annular calcium with acoustic shadowing and restricted leaflet bases |
| Planimetry | Reference method, at the leaflet tips | Unreliable in 2D — irregular, non-planar orifice; 3D may help |
| Pressure half-time | Usable, with the caveats above | Tends to overestimate valve area |
| Continuity equation | Alternative method | Closer to invasive area when mitral and aortic regurgitation are no more than mild |
| Mean gradient | Supportive | Often the most practical measure; quoted with heart rate |
| Balloon commissurotomy | Effective when the anatomy is suitable | No role — there is no commissural fusion to split |
In a catheter-comparison study of 40 patients with calcific mitral stenosis, pressure half-time overestimated valve area and the continuity equation agreed better with the invasive measurement [7]. Echo and catheter data were not simultaneous, and patients with more than mild mitral or aortic regurgitation were excluded. The study supports continuity as the preferred Doppler estimate in that setting; it does not make the method reliable in every patient with annular calcification.
Discordant Findings and Stress Echo
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| Pattern | Common explanations | Next step |
|---|---|---|
| MVA ≤ 1.5 cm² with mean gradient < 5 mmHg | Low transmitral flow — bradycardia, reduced stroke volume, atrial fibrillation — or an underestimated area | Area confirmed by planimetry, 3D where available; heart rate and stroke volume index recorded. Severe stenosis is not excluded. |
| MVA > 1.5 cm² with mean gradient ≥ 10 mmHg | Tachycardia, a high-output state (pregnancy, anaemia, thyrotoxicosis), significant mitral regurgitation, or a half-time that overestimates area | Repeat at a controlled heart rate; quantify the regurgitation; re-measure area by planimetry |
| Half-time and planimetry disagree | A half-time error (aortic regurgitation, compliance, recent procedure, bimodal slope) or a planimetry plane error | Good-quality planimetry takes precedence; 3D or continuity as a third method |
| Symptoms out of proportion to resting findings | Rate- and flow-dependent rise in gradient and pulmonary pressure on exertion | Exercise echo |
Stress Echo in Mitral Stenosis
Exercise is preferred to dobutamine: it reproduces the physiological rise in heart rate and flow, and symptoms and workload are observed at the same time [4, 8]. Reported markers of an abnormal haemodynamic response are a mean gradient above 15 mmHg with exercise (above 18 mmHg with dobutamine) and a PASP above 60 mmHg with exercise [8].
Wilkins Score and Balloon Commissurotomy Suitability
The Wilkins (Massachusetts General Hospital) score grades four features of rheumatic valve morphology from 1 to 4, for a total of 4–16 [9]. A score of 8 or less is conventionally taken as favourable for percutaneous balloon mitral commissurotomy (PBMC). The score does not assess the commissures, predicts post-procedural mitral regurgitation poorly, and does not decide suitability alone.
Wilkins Score
One grade for each component; the total appears once all four are selected. Full descriptors are in the table below.
A morphology score only. Commissural fusion and calcification, mitral regurgitation and left atrial thrombus are assessed separately — see the checklist below.
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| Component | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Leaflet mobility | Highly mobile valve with restriction of only the leaflet tips | Mid and base portions of the leaflets have normal mobility | Valve continues to move forward in diastole, mainly from the base | No or minimal forward movement of the leaflets in diastole |
| Leaflet thickening | Leaflets near normal in thickness (4–5 mm) | Mid-leaflets normal; considerable thickening of the margins (5–8 mm) | Thickening extending through the entire leaflet (5–8 mm) | Considerable thickening of all leaflet tissue (> 8–10 mm) |
| Calcification | A single area of increased echo brightness | Scattered areas of brightness confined to the leaflet margins | Brightness extending into the mid-portion of the leaflets | Extensive brightness throughout much of the leaflet tissue |
| Subvalvular thickening | Minimal thickening just below the mitral leaflets | Thickening of chordal structures extending up to one-third of the chordal length | Thickening extending to the distal third of the chordae | Extensive thickening and shortening of all chordal structures, extending down to the papillary muscles |
| Total score | Conventional band | What it suggests |
|---|---|---|
| ≤ 8 | Favourable | A higher likelihood of a good immediate result. Not sufficient alone: commissural anatomy, mitral regurgitation and left atrial thrombus still decide suitability. |
| 9 – 11 | Intermediate | Results are less predictable. Individualised by commissural morphology, subvalvular disease, clinical profile and surgical risk. |
| ≥ 12 | Unfavourable | A lower likelihood of a good or durable result. Surgery is usually considered when operative risk is acceptable; PBMC can still be reasonable in selected patients at high surgical risk. |
Eligibility Checklist Before PBMC
Suitability is decided on anatomy, associated lesions and the clinical picture together. The items below follow the ESC/EACTS contraindications and the ACC/AHA recommendations [3, 4].
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| Item | What to establish |
|---|---|
| Severity | Rheumatic stenosis with a valve area of 1.5 cm² or less. A larger area is a contraindication unless symptoms have no other explanation and the anatomy is favourable. |
| Commissural fusion | Present at one or both commissures. PBMC works by splitting fused commissures; absence of fusion is a contraindication. |
| Commissural calcification | Severe or bicommissural calcification is a contraindication. Asymmetric calcification raises the risk of leaflet tear and regurgitation. |
| Mitral regurgitation | ESC/EACTS: more than mild regurgitation is a contraindication. ACC/AHA: less than moderate (2+) regurgitation is required. |
| Left atrial thrombus | Excluded by transoesophageal echo before the procedure, including the appendage. |
| Other valve disease | Severe concomitant aortic valve disease, or severe combined tricuspid stenosis and regurgitation requiring surgery, is a contraindication. |
| Coronary disease | Concomitant coronary artery disease requiring bypass surgery is a contraindication. |
| Clinical profile | Older age, previous commissurotomy, NYHA class IV, permanent atrial fibrillation and severe pulmonary hypertension are unfavourable characteristics, not contraindications. |
Additional Scores — Padial and Nunes
Two further models address what the Wilkins score leaves out. Each answers a different question and neither replaces the checklist above.
Padial MR-echo score — risk of severe mitral regurgitation after PBMC
The Padial score predicts severe mitral regurgitation after balloon commissurotomy; it is not a predictor of procedural success [10]. It grades the anterior leaflet, the posterior leaflet, the commissures and the subvalvular apparatus from 1 to 4 each, for a total of 4–16. It weights uneven leaflet disease and asymmetric commissural calcification, where the balloon is more likely to tear a thin, pliable segment than to split the commissure.
| Component | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Leaflet thickening — anterior and posterior scored separately | Near normal (4–5 mm), or only one thick segment | Fibrotic or calcified evenly; no thin areas | Fibrotic or calcified unevenly; thinner segments mildly thickened (5–8 mm) | Fibrotic or calcified unevenly; thinner segments near normal (4–5 mm) |
| Commissural calcification | Fibrosis or calcium in one commissure only | Both commissures mildly affected | Calcium in both commissures, one markedly affected | Calcium in both commissures, both markedly affected |
| Subvalvular disease | Minimal thickening of chordal structures just below the valve | Thickening of chordae extending up to one-third of chordal length | Thickening extending to the distal third of the chordae | Extensive thickening and shortening of all chordae, extending down to the papillary muscles |
In the validation cohort treated with the Inoue balloon, a total of 10 or more predicted severe regurgitation with a sensitivity of 82%, a specificity of 91% and a negative predictive value of 97% [11]. These are results from that study rather than general performance figures.
Nunes score — immediate procedural outcome
The Nunes model adds commissural morphology and leaflet displacement to the prediction of a suboptimal immediate result [12]. It is an additional model, not an accepted replacement for the Wilkins score.
| Variable | How it is measured | Points |
|---|---|---|
| Mitral valve area ≤ 1.0 cm² | By planimetry | 2 |
| Maximum leaflet displacement ≤ 12 mm | Apical four-chamber view: maximal excursion of the leaflets from the annular plane in diastole | 3 |
| Commissural area ratio ≥ 1.25 | Parasternal short axis: ratio of the larger to the smaller area on either side of the orifice midline — a measure of asymmetric commissural disease | 3 |
| Subvalvular involvement | Extensive subvalvular thickening, as against absent or mild | 3 |
| Risk group | Total | Suboptimal result — derivation cohort | Validation cohort |
|---|---|---|---|
| Low | 0 – 3 | 16.9% | 11.8% |
| Intermediate | 5 | 56.3% | 72.7% |
| High | 6 – 11 | 73.8% | 87.5% |
Frequently Asked Questions
Why do mitral stenosis severity thresholds differ between references?
The 2009 EAE/ASE document graded a valve area above 1.5 cm² as mild, 1.0–1.5 cm² as moderate and below 1.0 cm² as severe. Later guidelines moved the severe threshold to 1.5 cm² or less, the level at which symptoms develop and intervention helps. ASE 2023 uses above 2.5 cm², 1.6–2.5 cm² and 1.5 cm² or less. A report should state which scale it uses.
Can severe mitral stenosis have a low gradient?
Yes. The gradient depends on flow and diastolic filling time as well as valve area. Bradycardia, a low stroke volume and atrial fibrillation can all leave the mean gradient below 5 mmHg with a valve area of 1.5 cm² or less. The area is confirmed by planimetry, and exercise echo helps when symptoms and resting findings disagree.
How is mitral valve area calculated from pressure half-time?
MVA (cm²) = 220 ÷ PHT (ms). Pressure half-time is the time for the peak gradient to halve, which is the time for velocity to fall to peak ÷ √2, and equals 0.29 × deceleration time on a linear slope. A half-time of 180 ms gives 1.2 cm².
When is pressure half-time unreliable?
With significant aortic regurgitation, reduced left ventricular compliance or an atrial septal defect, all of which shorten the half-time and overestimate valve area; in the days to weeks after balloon commissurotomy; with a bimodal slope, tachycardia or short diastoles; and in calcific mitral stenosis. Planimetry is the fallback in rheumatic disease.
Does a Wilkins score of 8 or less guarantee suitability for balloon commissurotomy?
No. The score describes leaflet and subvalvular morphology only. Absent commissural fusion, severe or bicommissural calcification, more than mild mitral regurgitation (ESC/EACTS) and left atrial thrombus each rule the procedure out whatever the score, and a patient with a higher score may still be offered it when surgical risk is high.
Does the grading table apply to calcific mitral stenosis?
Not directly. The table was developed for rheumatic disease, where the narrowest point is at the leaflet tips. In calcific stenosis the narrowing is at the annulus and leaflet bases, 2D planimetry is unreliable and pressure half-time tends to overestimate area. Mean gradient at a stated heart rate, 3D planimetry and the continuity equation carry more weight.
Related Echo References
References
- Pandian NG, Kim JK, Arias-Godinez JA, et al. Recommendations for the use of echocardiography in the evaluation of rheumatic heart disease: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2023;36(1):3–28. doi:10.1016/j.echo.2022.10.009
- Baumgartner H, Hung J, Bermejo J, et al. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. J Am Soc Echocardiogr. 2009;22(1):1–23. doi:10.1016/j.echo.2008.11.029
- Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease. Circulation. 2021;143(5):e72–e227. doi:10.1161/CIR.0000000000000923
- Praz F, Beyersdorf F, Haugaa K, Prendergast B, et al. 2025 ESC/EACTS guidelines for the management of valvular heart disease. Eur Heart J. 2025; ehaf194. doi:10.1093/eurheartj/ehaf194
- Hatle L, Angelsen B, Tromsdal A. Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound. Circulation. 1979;60(5):1096–1104. doi:10.1161/01.CIR.60.5.1096
- Thomas JD, Wilkins GT, Choong CY, et al. Inaccuracy of mitral pressure half-time immediately after percutaneous mitral valvotomy: dependence on transmitral gradient and left atrial and ventricular compliance. Circulation. 1988;78(4):980–993. doi:10.1161/01.CIR.78.4.980
- Saad JM, O'Sullivan S, et al. The continuity equation is superior to the pressure half-time method in calcific mitral stenosis: a comparison with cardiac catheterization. Eur Heart J Cardiovasc Imaging. 2025. doi:10.1093/ehjci/jeae253
- Lancellotti P, Pellikka PA, Budts W, et al. The clinical use of stress echocardiography in non-ischaemic heart disease: recommendations from the European Association of Cardiovascular Imaging and the American Society of Echocardiography. Eur Heart J Cardiovasc Imaging. 2016;17(11):1191–1229. doi:10.1093/ehjci/jew190
- Wilkins GT, Weyman AE, Abascal VM, Block PC, Palacios IF. Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation. Br Heart J. 1988;60(4):299–308. doi:10.1136/hrt.60.4.299
- Padial LR, Freitas N, Sagie A, et al. Echocardiography can predict which patients will develop severe mitral regurgitation after percutaneous mitral valvulotomy. J Am Coll Cardiol. 1996;27(5):1225–1231. doi:10.1016/0735-1097(95)00594-3
- Padial LR, Abascal VM, Moreno PR, Weyman AE, Levine RA, Palacios IF. Echocardiography can predict the development of severe mitral regurgitation after percutaneous mitral valvuloplasty by the Inoue technique. Am J Cardiol. 1999;83(8):1210–1213. doi:10.1016/S0002-9149(99)00061-2
- Nunes MCP, Tan TC, Elmariah S, et al. The echo score revisited: impact of incorporating commissural morphology and leaflet displacement to the prediction of outcome for patients undergoing percutaneous mitral valvuloplasty. Circulation. 2014;129(8):886–895. doi:10.1161/CIRCULATIONAHA.113.001252