AR Severity Criteria: How to Read VC, EROA, Regurgitant Volume, and Regurgitant Fraction
AR severity is not decided by a single number. The AR Severity Tool looks for concordance across echo findings — and when signals conflict, returns that conflict as the result.
Read AR severity by concordance across VC, EROA, regurgitant volume, regurgitant fraction, and diastolic flow reversal. PHT is context, not a primary severity signal.
Key takeaway
The AR Severity Tool is built around concordance. Two or more severe signals establish a severe AR pattern. One severe signal leaves uncertainty. Severe and non-severe signals together produce a discordant result — not because the tool failed, but because the data need review.
Key points
- The main quantitative severe signals are VC ≥ 0.60 cm, EROA ≥ 0.30 cm², regurgitant volume ≥ 60 mL/beat, and regurgitant fraction ≥ 50%.
- A qualitative grade of severe counts as one severe signal in the tool.
- Descending aortic holodiastolic flow reversal counts as one severe signal.
- Abdominal aortic holodiastolic reversal is treated as strong supportive context, not a counted severe signal by itself.
- Two or more severe signals produce severe_ar_pattern. One severe signal produces possible / likely / discordant depending on the rest of the data.
- discordant_ar does not mean moderate AR. It means severe and non-severe data coexist.
- PHT is accepted as context but is not counted as a severe signal.
When to read this
Read this when the AR Severity Tool does not return severe_ar_pattern but clinical suspicion remains high, or when the parameters do not agree — for example, severe VC with non-severe regurgitant volume, or short PHT with otherwise non-severe quantitative data.
The five severe AR parameters
| Parameter | Severe threshold | What it measures | Key limitation |
|---|---|---|---|
| Vena contracta (VC) | ≥ 0.60 cm | Width of the regurgitant jet at its narrowest point at the valve level | Sensitive to gain settings, beam angle, and image quality |
| EROA (PISA method) | ≥ 0.30 cm² | Cross-sectional area of the regurgitant orifice, estimated from the proximal isovelocity surface area | Assumes spherical flow convergence — less reliable for eccentric or complex jets |
| Regurgitant volume | ≥ 60 mL/beat | Volume of blood regurgitating per beat (EROA × AR velocity–time integral) | Requires accurate LVOT diameter and stroke-volume measurements |
| Regurgitant fraction | ≥ 50% | Proportion of total LV stroke volume that regurgitates | Depends on the accuracy of both forward and total stroke volume |
| Qualitative grade (severe) | Visual grading | Integrated visual assessment of jet width, density, and reach relative to LV dimensions | Operator-dependent — use as corroborating evidence, not as the sole grading basis |
| Descending aortic holodiastolic reversal | Present | Retrograde diastolic flow throughout diastole in the descending aorta — indicates significant regurgitant volume reaching the peripheral circulation | Site matters: descending aorta counts as a signal; abdominal aorta alone is supportive context only |
| Pressure half-time (PHT) | No threshold — context only | Rate of LV–aortic diastolic pressure equalization — reflects loading conditions and LV compliance, not regurgitant volume directly | PHT is not a counted severe signal. A short PHT does not independently confirm severe AR. |
AR severity ranges: mild, moderate, and severe
| Parameter | Mild | Moderate | Severe | Key limitation |
|---|---|---|---|---|
| Vena contracta (VC) | < 0.3 cm | 0.3–0.6 cm | > 0.6 cm | Sensitive to gain settings, beam angle, and image quality |
| EROA (PISA method) | < 0.10 cm² | 0.10–0.29 cm² | ≥ 0.30 cm² | PISA assumptions may break down with eccentric or complex jets |
| Regurgitant volume | < 30 mL/beat | 30–59 mL/beat | ≥ 60 mL/beat | Depends on accurate LVOT diameter and stroke-volume measurements |
| Regurgitant fraction | < 30% | 30–49% | ≥ 50% | Requires accurate estimates of both total and forward stroke volume |
| Qualitative grade | mild | moderate | severe | Operator-dependent; do not use as the sole basis for grading |
| Descending aortic holodiastolic flow reversal | Usually absent | Supportive finding | Present | Descending aortic reversal counts as a severe signal; abdominal aortic reversal alone is supportive context |
| Pressure half-time (PHT) | — | — | — | PHT is not a counted severe signal. A short PHT does not independently confirm severe AR |
Why concordance matters more than any single parameter
Every parameter has limitations. Vena contracta depends on image quality, gain, and beam alignment. PISA-derived EROA assumes a simplified flow convergence geometry and can be unreliable in eccentric or complex jets. Regurgitant volume depends on accurate diameter and stroke-volume measurements. Regurgitant fraction depends on the accuracy of both forward and total stroke volume.
That is why the tool does not let one number dominate the entire result. Concordance is the signal. When multiple independent findings point in the same direction, the severity call becomes more reliable.
Holodiastolic flow reversal: location matters
Holodiastolic flow reversal in the descending aorta is counted as one severe signal in the tool because it strongly supports severe AR.
Abdominal aortic holodiastolic reversal is also important, but the tool treats it as supportive context rather than a counted severe signal on its own. If one quantitative severe signal is already present, abdominal reversal can raise the result toward likely severe AR. If abdominal reversal is the only major finding entered, the tool returns supportive_severe_ar_finding_only — a warning that significant AR is possible, but the severity picture is incomplete.
What discordant AR means
discordant_ar means that at least one severe signal and at least one non-severe signal are both present. It is not the same as saying "moderate AR." It means the data are internally inconsistent.
Common reasons include LVOT diameter or stroke-volume measurement error, suboptimal color Doppler settings, eccentric jets, altered loading conditions, acute versus chronic physiology, or mixed valve disease.
The next step is not to accept the severe value or the non-severe value at face value. The next step is to find out why the data disagree.
Why PHT is context, not a counted signal
Pressure half-time can be useful context, but it is not counted as a severe signal in the tool.
PHT reflects how quickly aortic and LV diastolic pressures equalize. It does not directly measure regurgitant volume. It is influenced by blood pressure, preload, afterload, LV compliance, and whether AR is acute or chronic.
When PHT conflicts with quantitative parameters, the quantitative measurements and image quality should be reviewed. PHT alone should not drive the severity grade.
Chronic AR: LV response thresholds are separate from severity grading
In chronic severe AR, LV response thresholds are evaluated in the Intervention Navigator — they are not part of severity grading. LV enlargement does not make AR more severe. What it signals is that the ventricle's adaptation to volume overload is changing, which shifts the intervention timing conversation.
| Threshold | Value | Key note |
|---|---|---|
| LVEF | ≤ 55% (inclusive) | 55% itself triggers the LV dysfunction pathway — values at 55% are not reassuring |
| LVESD | > 50 mm (strictly greater than) | 50 mm exactly does not meet the threshold — must be strictly above 50 mm |
| LVESDi | > 25 mm/m² | Indexed alternative — useful when body-size adjustment is clinically relevant |
| LVEDD | > 65 mm | Softer trigger — prompts closer follow-up and specialist discussion, not equivalent in weight to LVEF or LVESD |
LV data and AR grade are answered separately
LVEF and LVEdd entered into the Severity Tool contribute to staging context but do not change the AR grade. The Intervention Navigator evaluates LV response through separate input fields, after severity context is established.
Acute AR: do not apply chronic LV thresholds
In acute AR, normal LVEF and normal LV size are not reassuring
In suspected acute AR, the LV has not had time to dilate or compensate. A normal-sized ventricle facing an abrupt volume burden may have severely elevated filling pressures despite normal LVEF and normal LV dimensions. The chronic LV thresholds (LVEF ≤ 55%, LVESD > 50 mm, LVEDD > 65 mm) were derived from chronic AR populations and do not apply to the acute setting. Acute AR (dissection, endocarditis, prosthetic dehiscence) is an urgent evaluation pathway — not a perioperative management variant of chronic AR.
Perioperative relevance
- AR is better tolerated at higher heart rates — bradycardia prolongs diastole and increases regurgitant fraction. Avoid heart rate targets that are appropriate for AS but harmful in AR.
- High systemic vascular resistance worsens regurgitation. Vasodilators are better tolerated than vasoconstrictors in significant AR.
- In acute AR (dissection, endocarditis, prosthetic dehiscence), the LV has not adapted — normal LV size and normal LVEF do not exclude hemodynamically significant regurgitation.
- discordant_ar in the preoperative setting warrants specialist review before elective non-cardiac surgery. One severe parameter with conflicting data is not sufficient to plan anesthesia as if severity is established.
- Severe AR with recent-onset symptoms or deteriorating LV function is not a stable perioperative risk — it requires cardiology input regardless of the planned procedure.
The most common perioperative misread
Relying on a short PHT alone to confirm severe AR in the perioperative assessment. PHT reflects how quickly aortic and LV diastolic pressures equalize — not how much blood is regurgitating. A short PHT can result from elevated LV diastolic pressure, tachycardia, or reduced LV compliance unrelated to AR severity. In the perioperative context, quantitative parameters (VC, EROA, regurgitant volume, regurgitant fraction) and holodiastolic flow reversal are more reliable anchors.
- Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. J Am Coll Cardiol. 2021;77(4):e25-e197.
- Zoghbi WA, et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation. J Am Soc Echocardiogr. 2017;30(4):303-371.
Related valve learning
Apply this in practice
Enter available severity parameters to see how the tool integrates them into a grade.
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