Primary Degenerative Mitral Regurgitation: An MDT-Focused Framework for Timing Intervention

Primary (Degenerative) Mitral Regurgitation: The UK MDT Playbook for Timing, Imaging, and Choosing the Right Intervention

There’s a moment every valve MDT recognises.

The patient looks well. They’re active. They’re “asymptomatic.” The echo report says “severe MR,” but the LV ejection fraction is still “normal.” The referral letter asks: Can we watch?

And that’s exactly where excellent teams win—or quietly lose.

Degenerative MR is the classic condition where being late feels safe… until it isn’t. By the time the LV finally “admits defeat,” the price has often already been paid.

This isn’t a blog about MR definitions. It’s a consultant’s operational playbook—how to think, how to report, and how to avoid the two most expensive mistakes in degenerative MR:

1. Under-calling severity (especially eccentric jets).
2. Over-waiting for “LV dysfunction” and pretending that EF is an early warning system.

It isn’t.

Step 1 — Stop treating “degenerative MR” like one diagnosis

Degenerative MR is not one entity. It’s a family of diseases with different trajectories, different repair complexity, and different durability profiles.

Phenotype it, or you’re guessing.

The practical phenotype map

• Fibroelastic deficiency (FED): focal chordal rupture, thin leaflets, often a “clean” repair target.
• Barlow / myxomatous disease: redundant tissue, often bileaflet, annular dilatation; repair is feasible but more complex.
• Flail leaflet: often P2 but not always; clinically, this is the phenotype that tends to punish delay.

Expert opinion:
If you don’t specify FED vs Barlow vs flail, you can’t honestly talk about repair probability, complexity, or long-term success.

Step 2 — The natural history numbers that should change your behaviour

Most clinicians have heard “severe MR is bad in the long term.” That’s not useful. What matters is knowing how fast the cliff edge arrives—and which phenotype gets there first.

Flail leaflet severe MR is not a “slow burn”

Landmark flail-leaflet cohorts showed striking long-term event rates under medical management—high rates of heart failure, atrial fibrillation, and progression to death or surgery over time.

Translation for the MDT room:
A “well-looking” patient with flail severe MR is often living on borrowed time. “Watchful waiting” is only defensible if follow-up is tight and your surgical repair pathway is genuinely elite.

Step 3 — Guidelines are moving “earlier,” but they’re also moving “smarter”

The old trap: waiting for EF to drop

ACC/AHA thresholds (EF ≤60% and/or LVESD ≥40 mm) are still quoted widely—and they remain important.

But here’s the hard truth:
EF is often preserved until late in chronic MR. An EF of 62% in severe MR is not “reassuring”; it can be a warning label.

ESC/EACTS 2025: early surgery is no longer just a concept — it is being operationalised

In asymptomatic severe primary MR with preserved LV function, ESC/EACTS explicitly supports considering surgery not only for atrial fibrillation or resting pulmonary hypertension (SPAP >50 mmHg), but also for significant left atrial dilatation when surgical risk is low and a durable repair in a Heart Valve Centre is likely (e.g. LAVI ≥60 mL/m² or LA diameter ≥55 mm).

And the direction of travel is clear: EACTS highlights a new Class I recommendation for mitral valve repair surgery in selected asymptomatic primary MR patients meeting defined criteria.

Expert opinion:
2025 guidance is effectively saying: “Don’t wait for LV damage if you already have strong surrogate signals that the atrium and pulmonary circuit are paying the price.” That’s a grown-up strategy—because it aligns with what experienced MDTs already know.

Step 4a — In the UK, the key question isn’t “surgery or not?”

It’s: “Where will this repair be done, and how good will it be?”

Early surgery only “wins” when repair quality is excellent and residual MR is near-zero.

The KPI isn’t “repair rate.” It’s durable repair with minimal residual MR.

Classic series show very strong long-term freedom from reoperation after degenerative repair, but “freedom from reoperation” is not the same as “no recurrent MR on echo.”

Practical MDT rule:
If your centre delivers predictably durable repair, early intervention becomes rational.
If repair is variable, “early surgery” becomes a slogan that can backfire.

These recommendations assume low procedural risk, high likelihood of durable repair, and a realistic expectation of functional benefit.

Step 4b — The Other Side of the Coin: Frailty, Futility, and Quality of Life

Early intervention in degenerative MR should never be interpreted as a blanket mandate. Frailty, multimorbidity, limited life expectancy, and realistic impact on quality of life must be weighed alongside anatomy and guideline thresholds. In some patients, the question is not whether intervention is technically possible, but whether it is meaningful.

Severe frailty, advanced non-cardiac disease, or limited functional reserve may render both surgery and transcatheter intervention futile, even when anatomical criteria are met. In these scenarios, MDT decisions should prioritise symptom burden, patient goals, proportionality of intervention, and anticipated quality-of-life gain, rather than procedural success alone.

A technically successful valve intervention that does not translate into functional or symptomatic improvement is not a clinical victory.

This is where experienced MDTs earn their value — by knowing not only when to intervene, but when not to.

Step 5 — The echo report must be an MDT tool, not a descriptive paragraph

In UK practice, your echo report is often the single most powerful determinant of timing—especially when symptoms are ambiguous.

The BSE-aligned approach: integrative MR grading, not one-number worship

MR severity should be graded using an integrative approach that respects limitations and avoids single-parameter overconfidence.

The “eccentric jet” trap (the most common way people under-call severe MR)

Eccentric jets can look smaller, cling to the atrial wall, and lull teams into “moderate-to-severe” comfort language.

Operational fix:
• Morphology and mechanism first (prolapse vs flail, segment involvement, chordal rupture)
• Use multiple severity markers, not a single parameter
• Escalate to TOE when needed—especially if intervention is being considered

Step 6 — TEER in degenerative MR

A risk-management tool, not a replacement for high-quality repair

Let’s be honest: TEER has transformed care for the right patient. But degenerative MR is exactly where sloppy thinking causes bad outcomes.

What the contemporary data actually tells you

In a large contemporary cohort, at 1 year after degenerative MR TEER:

• Death: 15.4%
• Reintervention: 3.4%
• HF admission: 9.3%
  
  …and procedural “success” (MR reduction) strongly separated outcomes.

This is the point most people miss:
Residual MR isn’t “acceptable because they’re high risk.” Residual MR is a prognostic toxin.

In patients with advanced frailty or limited life expectancy, even transcatheter intervention may offer little meaningful benefit and should be considered carefully within a patient-centred MDT discussion.

UK best-practice reality

NICE has evaluated percutaneous mitral leaflet repair (TEER) within its interventional procedures framework, with UK specialist society involvement.

And NICE guideline work supports considering transcatheter repair for severe symptomatic primary MR when surgery is unsuitable—explicitly acknowledging the evidence limitations in primary MR.
Meanwhile, NHS England’s ongoing evidence reviews reflect the real-world UK environment: access is expanding, but scrutiny of benefit and value is active.

UK MDT framing:

• Operable degenerative valve + high likelihood of durable repair → surgery is the gold standard.
• High/prohibitive surgical risk + suitable anatomy → TEER is a sensible risk-management strategy.
• If you can’t achieve low residual MR, don’t pretend you’ve “fixed” the valve. You’ve just deferred the problem. 

“Don’t Get Burned” Checklist (Primary Degenerative MR)

1) Eccentric jets

Don’t under-grade. Use an integrative approach; confirm mechanism and severity properly.

2) The EF trap

EF often stays “normal” until late. Treat EF 60% as a warning line, not reassurance.

3) LVESD matters—but so does context

Use indexing when relevant, and don’t ignore atrial and pulmonary consequences. (ESC 2025 now explicitly gives LA dilatation thresholds that matter.)

4) Centre capability is an outcome modifier

Early surgery only wins when repair quality is elite and residual MR is minimal. (This is not marketing—it is the entire game.)

5) TEER is about achieving success, not “doing the procedure”

In degenerative MR TEER, outcomes separate sharply by MR reduction success.

MDT-ready echo report phrasing

Mechanism / phenotype:
“Degenerative MR due to [FED / myxomatous-Barlow / flail] with [segment/scallop], consistent with [prolapse/flail] mechanism.”

Severity (integrative):
“Findings are consistent with severe MR on an integrative assessment (valve morphology + jet characteristics + quantitative/semiquantitative parameters).”

Consequences (the part that drives timing):
“LV size and function: [EF, LVESD/LVESDi]. LA: [LAVI/LA diameter].
Estimated SPAP: [ ]. Rhythm: [AF?].”

Interpretive Comment (Flag for the Referring Team):
"Severe primary mitral regurgitation is present. Associated features are noted, including [atrial fibrillation / resting SPAP >50 mmHg / significant left atrial dilatation]. Clinical correlation is advised."

The Action (Responsibility of the Referring Clinician): 
The referring clinician should correlate with clinical status, functional capacity, comorbidities, frailty, and patient preferences. Then, consider Heart Valve MDT discussion to evaluate suitability for durable mitral valve repair in a Heart Valve Centre, where appropriate.

Closing: the one-sentence strategy that wins in degenerative MR

Degenerative MR rewards teams who do three things consistently:

1. Phenotype the valve properly
2. Treat atrial/pulmonary consequences as timing signals—not afterthoughts (ESC 2025 now codifies this thinking)
3. Choose the intervention that produces the best durable MR result for that patient—within real UK pathways

Everything else is noise.

Good MDTs are defined not only by how well they intervene, but by how well they judge when intervention is — and is not — in the patient’s best interest.

References

• 2025 ESC/EACTS VHD Guidelines (primary MR early surgery triggers incl. LA dilatation thresholds).
• JAMA 2023 degenerative MR TEER outcomes (1-year death/reintervention/HF admission; success vs failure gradient).
• NICE IPG649 overview: percutaneous mitral valve leaflet repair (TEER) evidence context.
• NHS England TEER evidence review (Jan 2026): UK commissioning/evidence context.

Dr Mohamed Mansour
Consultant Cardiologist | Cardiac Imaging Specialist
EchoMasters Insights
Master Echocardiography. Lead with Confidence.

Disclaimer

Content published under the EchoMasters brand is intended for healthcare professionals and is provided for educational purposes only. It reflects the author’s personal expert interpretation of the available scientific evidence, clinical guidelines, and professional practice at the time of writing.

This content does not constitute clinical advice, formal guidance, or institutional policy, and should not be used as a substitute for local protocols, official guideline documents, or multidisciplinary team (MDT) decision-making. Clinical management decisions must always be individualised, made within appropriate clinical governance frameworks, and aligned with local regulatory and institutional requirements.

EchoMasters accepts no liability for clinical decisions made on the basis of this content.