Why EROA 0.20 is not the severe threshold in this tool
This tool does not use EROA 0.20 cm² as the severe diagnostic threshold for secondary MR. ACC/AHA 2020 applies the same quantitative severe range to secondary MR as to primary MR. The key is to separate a guideline severe threshold from a prognostic signal.
You see EROA 0.22 cm² in a patient with HFrEF and secondary MR. A colleague says, 'It is above 0.20, so this is severe secondary MR by guideline criteria.' That interpretation is not accurate. EROA 0.22 cm² may be clinically important in the context of LV dysfunction. But it does not mean the ACC/AHA severe secondary MR threshold has been crossed.
Key takeaway
ACC/AHA 2020 uses the same quantitative severe range for secondary MR as for primary MR: EROA ≥ 0.40 cm² and regurgitant volume ≥ 60 mL/beat. EROA 0.20–0.39 cm² may be prognostically relevant in secondary MR, but it is not a redefined severe threshold. This tool separates 'guideline-severe secondary MR' from 'clinically important secondary MR in context.'
Key points
- ACC/AHA 2020 severe quantitative range for secondary MR includes EROA ≥ 0.40 cm² and regurgitant volume ≥ 60 mL/beat.
- Regurgitant fraction ≥ 50% may be used as an additional severe MR marker when available.
- EROA 0.20–0.39 cm² may be associated with worse outcomes in secondary MR populations, but it does not redefine the guideline severe threshold.
- The prognostic importance of lower EROA values reflects the vulnerability of an already remodeled or failing LV to additional volume load.
- This tool may classify non-severe-range findings as 'clinically important in context' when LV dysfunction, symptoms, or elevated pulmonary pressure are present.
- Calling EROA 0.20 cm² 'severe secondary MR' can conflate a prognostic signal with a guideline diagnosis and may push intervention discussions too early.
When to read this
Read this when the tool returns 'clinically important secondary MR in context' and you wonder whether EROA 0.22 cm² should instead be labeled severe. Also read this when a report or colleague is using EROA 0.20 cm² as the severe threshold for secondary MR.
What ACC/AHA 2020 actually says
ACC/AHA 2020 defines severe secondary MR using the same quantitative severe range as severe primary MR. The key quantitative findings are EROA ≥ 0.40 cm² and regurgitant volume ≥ 60 mL/beat. The guideline does not lower the secondary MR severe threshold to EROA ≥ 0.20 cm². Saying that 'ACC/AHA redefined severe secondary MR as EROA ≥ 0.20 cm²' is a misreading of the evidence.
Where the 0.20 number comes from
The EROA 0.20 cm² signal comes from outcome studies in secondary MR populations. In patients with LV dysfunction or advanced remodeling, EROA values around 0.20 cm² may be associated with HF hospitalization, mortality, or other adverse outcomes. This likely reflects the fact that an already compromised ventricle is less tolerant of additional regurgitant volume.
This finding matters clinically. But it does not change the guideline definition of severe MR. Secondary MR below the severe quantitative range should not be dismissed automatically. It should be interpreted with LV function, symptoms, pulmonary pressure, remodeling severity, and response to GDMT.
How this tool distinguishes the categories
| Category | What it means | Clinical implication |
|---|---|---|
| Guideline-severe secondary MR pattern | EROA ≥ 0.40 cm² or regurgitant volume ≥ 60 mL/beat — ACC/AHA severe range met | Evaluate GDMT optimization, symptoms, LV size/function, PASP, anatomy, and intervention candidacy. |
| Likely severe secondary MR | Strong quantitative signal but incomplete data for confirmation | Confirm with integrated echocardiographic assessment; consider TEE or CMR when needed. |
| Clinically important secondary MR in context | Below ACC/AHA severe quantitative range, but with LV dysfunction, symptoms, or elevated PASP suggesting prognostic importance | Do not label as guideline-severe. Do not dismiss. Optimize GDMT and monitor symptoms, remodeling, and pulmonary pressure. |
| Discordant / indeterminate | Parameters conflict or measurement quality is uncertain | Recheck measurements. Consider repeat TTE, TEE, or CMR. |
Why the distinction matters in practice
Calling EROA 0.22 cm² 'severe secondary MR' can push a patient toward TEER or surgical consultation before GDMT has been adequately optimized. Intervention for secondary MR is not based on EROA above 0.20 alone. In ACC/AHA 2020, TEER is considered for selected patients with chronic severe secondary MR who remain symptomatic despite optimal GDMT and meet anatomic and clinical criteria. The starting point is not 'EROA above 0.20.' It is confirmed severe secondary MR despite optimized medical therapy. Misusing the threshold can overstate intervention urgency and underemphasize the chance that MR may improve or stabilize with GDMT.
Clinically important is not the same as guideline-severe
When this tool returns 'clinically important secondary MR in context,' it means the MR may carry prognostic weight in this patient's LV remodeling or HF context — not that the ACC/AHA severe diagnostic threshold has been crossed. These statements lead to different next steps. 'Clinically important in context' should prompt GDMT optimization, HF stability assessment, pulmonary pressure review, and LV/RV function follow-up. 'Guideline-severe secondary MR' should prompt assessment of persistent symptoms after GDMT, TEER anatomy, LVEF/LVESD/PASP criteria, and whether surgery is being considered for another indication.
Apply this in practice
Use the Secondary MR Severity Tool to interpret your patient's parameters in context.
Secondary MR Severity Tool