Severe Mitral Regurgitation and the MitraClip: A Cardiologist's Guide to TEER, COAPT, and Patient Selection

Few decisions in structural heart disease have changed as much over the past decade as what to do about severe mitral regurgitation. Twenty years ago, the only real options were open-heart surgery or medical therapy, and for older, sicker patients the math often did not work. Today, in my Encinitas practice, I sit with patients and walk them through a third option: transcatheter edge-to-edge repair (TEER), performed most commonly with the MitraClip device. For the right patient, it can add years of life and keep people out of the hospital. For the wrong patient, it is an expensive procedure that does not help. This guide walks through how to tell the difference.

What Is Severe Mitral Regurgitation?

Severe mitral regurgitation is a leak in the mitral valve that allows a large volume of blood (≥ 60 mL/beat or ≥ 50% regurgitant fraction) to flow backward into the left atrium with every heartbeat. Left untreated, it overloads the left ventricle, raises pulmonary pressures, and produces progressive heart failure. The two clinical categories, primary (degenerative) and secondary (functional), have fundamentally different treatments.

The mitral valve sits between the left atrium and the left ventricle. With every beat, it opens to allow oxygenated blood from the lungs to fill the ventricle, then snaps shut so that the ventricular contraction pushes the blood forward through the aortic valve rather than backward into the atrium. The apparatus, two leaflets (anterior and posterior), the chordae tendineae, the papillary muscles, and the mitral annulus, must work as a unit. Damage to any component produces a leak.

Primary (degenerative) MR is a problem with the valve itself: a structurally abnormal leaflet, ruptured chordae, mitral valve prolapse, endocarditis, or rheumatic damage. The most common form is myxomatous mitral valve prolapse with chordal rupture, which usually affects the posterior leaflet. The leaflet flails into the atrium during systole and blood escapes around it.

Secondary (functional) MR is a problem with the heart muscle around an otherwise structurally normal valve. The ventricle has dilated or scarred, usually from prior myocardial infarction or a nonischemic cardiomyopathy. The papillary muscles get pulled outward, the leaflets tether down, and they cannot reach each other to close. Long-standing atrial fibrillation can produce a similar atrial-secondary MR through atrial dilation alone.

These two diseases look superficially similar on an echocardiogram but are fundamentally different. Primary MR is fixed by repairing or replacing the valve. Secondary MR is treated first by optimizing the underlying cardiomyopathy or atrial fibrillation; the valve intervention is layered on if the leak persists.

How Is Severe MR Graded?

Severe MR is defined by an effective regurgitant orifice area (EROA) ≥ 0.40 cm², regurgitant volume ≥ 60 mL/beat, regurgitant fraction ≥ 50%, and supporting features like vena contracta width ≥ 7 mm, large flail leaflet, or reversed pulmonary vein flow. Severity grade drives every clinical decision, and accurate grading requires an experienced imaging center.

MR Severity Grading (ACC/AHA criteria)

The cornerstone test is the transthoracic echocardiogram (TTE). When the study is inconclusive or when intervention is being planned, a transesophageal echocardiogram (TEE) puts the probe directly behind the heart and produces images of the mitral apparatus that surface imaging cannot match. Cardiac MRI is the third-line tool for accurate regurgitant volume quantification when echo is technically limited.

For secondary MR specifically, the 2020 ACC/AHA valvular heart disease guideline uses the same EROA cutoff of 0.40 cm² but emphasizes whether the leak is “disproportionate” to the ventricle size. The Grayburn framework distinguishes proportionate secondary MR (where the leak scales with LV enlargement, and treating the valve does not change the underlying cardiomyopathy) from disproportionate secondary MR (where the leak is severe out of proportion to LV size, and treating the valve produces meaningful benefit). This distinction explains why COAPT and MITRA-FR reached different conclusions in similar-looking trials.

What Is the MitraClip and How Does TEER Work?

The MitraClip is a small cobalt-chromium clip lined with polyester fabric, delivered through a catheter inserted in the femoral vein, advanced through the right atrium, across the atrial septum via a transseptal puncture, and into the left atrium. Under transesophageal echo and fluoroscopic guidance, the operator grasps the anterior and posterior leaflets at the leak and closes the clip. The result is a double-orifice mitral valve with the leak substantially reduced.

The procedure is performed under general anesthesia and takes about 2 to 3 hours. The clip is positioned at the most stenotic part of the leak (typically the central A2-P2 zone). One or more clips can be placed if needed. The result is not a perfect valve; the goal is to drop the regurgitation from severe to mild or moderate, ideally grade 1 or less residual MR with a mean gradient under 5 mmHg. That reduction, when durable, translates into fewer hospitalizations and better survival.

The PASCAL device is a newer-generation TEER system with a different leaflet-grasp mechanism. The CLASP IID trial established non-inferiority to MitraClip in primary MR. Both devices remain in active clinical use and the choice between them is largely operator preference and anatomic suitability.

Recovery from TEER is dramatically faster than from surgical mitral valve replacement. Hospital stay is typically 1 to 2 days. Most patients walk the same day, return to light activity within a week, and feel near baseline within 2 to 3 weeks. No sternotomy. No cardiopulmonary bypass.

What Did the COAPT Trial Show?

The COAPT trial (NEJM 2018, 5-year follow-up 2023) randomized 614 patients with heart failure and severe secondary MR on optimal medical therapy to MitraClip plus medical therapy or medical therapy alone. At two years, MitraClip cut heart failure hospitalizations by 47% and all-cause mortality by 38%. The five-year follow-up confirmed the durability of the benefit.

COAPT is the single most important trial in this space. Patients had to be symptomatic (NYHA II to IV) despite documented optimization of medical therapy with an ACE inhibitor or ARB (or sacubitril-valsartan), beta-blocker, and mineralocorticoid receptor antagonist. Severe MR was defined by EROA ≥ 0.30 cm² or other quantitative criteria; the mean EROA at enrollment was 0.40 cm².

At two years, heart failure hospitalizations dropped from 67.9 to 35.8 per 100 patient-years (HR 0.53, p < 0.001). All-cause mortality fell from 46.1% to 29.1% (HR 0.62, p < 0.001). The number needed to treat (NNT) to prevent one heart failure hospitalization was about 3.1 over two years; the NNT to prevent one death was about 5.9. These are striking numbers for any cardiovascular intervention.

The five-year follow-up published in 2023 confirmed durability. Heart failure hospitalization rates were 33.1 per 100 patient-years in the device arm versus 57.2 in the control arm (HR 0.53). All-cause mortality was 57.3% versus 67.2% (HR 0.72). The composite of death or HF hospitalization was 73.6% versus 91.5% (HR 0.53). Time alive and out of hospital improved by roughly 2 months over the first 2 years and continued to favor MitraClip out to 5 years.

When a patient with heart failure and severe secondary MR meets the COAPT profile, the MitraClip is the closest thing to a disease-modifying structural intervention available outside of transplant.

Why Was MITRA-FR Different?

MITRA-FR enrolled 307 similar-looking patients and showed no benefit. The two trials diverged because COAPT patients had severe MR out of proportion to ventricular dilation (disproportionate MR) and optimized medical therapy, while MITRA-FR patients had less severe MR (mean EROA 0.31), more LV dilation, less uniformly optimized therapy, and less MR reduction with the procedure. The Grayburn “proportionate vs disproportionate” framework explains the difference.

MITRA-FR published almost the same time as COAPT and reached the opposite conclusion: no difference in death or heart failure rehospitalization at 12 months. The patient populations looked similar on the surface, but several distinctions mattered.

Mean EROA in MITRA-FR was 0.31 cm², below the COAPT mean of 0.40. LV end-diastolic volume was substantially larger in MITRA-FR (about 250 mL/m² vs 200 in COAPT). Medical therapy optimization was less uniform; only some patients were on optimal guideline-directed therapy at enrollment. Procedural MR reduction was less complete (more patients left the cath lab with moderate or severe residual MR).

The synthesis, articulated most clearly by Grayburn and colleagues, is that secondary MR comes in two forms. Disproportionate secondary MR is where the regurgitant volume is severe relative to the size of the LV. Here, the valve intervention reduces a clinically significant leak and produces measurable benefit. Proportionate secondary MR is where the LV is so dilated that even a “severe” looking jet is proportionate to the ventricle volume. Here, the underlying cardiomyopathy dominates and fixing the valve does not change outcomes meaningfully. COAPT enrolled disproportionate MR; MITRA-FR enrolled more proportionate disease.

This distinction now drives every secondary-MR referral. The pre-procedure echo and the heart-team discussion explicitly assess proportionality before any patient is sent for TEER.

What Did RESHAPE-HF2 Add?

RESHAPE-HF2 (NEJM 2024) extended the secondary-MR evidence to patients with moderate-to-severe MR (mean EROA only 0.25, with only 14% of patients above 0.40). At 24 months, TEER reduced the composite of cardiovascular death or heart failure hospitalization (HR 0.65) and recurrent heart failure hospitalizations (rate ratio 0.59). The NNT to prevent one heart failure hospitalization was 5.1.

RESHAPE-HF2 expanded the evidence base from the narrow COAPT severity profile to a broader population with moderate-to-severe secondary MR. The benefit was real, the relative risk reductions were smaller than COAPT, consistent with a less severe baseline leak. RESHAPE-HF2 does not mean every patient with a moderate functional leak should be clipped. It does mean we have stronger evidence for a broader group than we did a few years ago.

The combined COAPT + RESHAPE-HF2 picture is now clearer: in secondary MR with optimized medical therapy and persistent symptoms, TEER reduces heart failure hospitalizations and (in COAPT) death. The size of the benefit scales with the severity of the leak and the proportionality framework.

Primary MR: A Different Decision Tree

For primary MR, surgical mitral valve repair remains the gold standard at low or intermediate operative risk. MitraClip is reserved for patients at high or prohibitive surgical risk. Three ongoing randomized trials (REPAIR MR, PRIMARY, MITRA HR) are testing TEER against surgery in lower-risk older patients with primary MR; results over the next several years will reshape the decision tree.

Surgical mitral valve repair for degenerative MR is excellent in experienced centers. Contemporary repair rates approach 95%, operative mortality is under 1% in elective cases, and durability extends well past 20 years. The 2020 ACC/AHA guideline gives surgery a Class I recommendation for severe symptomatic primary MR and for many asymptomatic patients with preserved LV function at low or intermediate operative risk.

MitraClip in primary MR is a high-surgical-risk procedure. The STS/ACC TVT Registry has now tracked more than 19,000 primary-MR patients treated with TEER. Median age was 82, median STS risk score 4.6%. Procedural success (residual MR ≤ mild with a mean gradient < 10 mmHg) was 88.9%, and improved over time as operator experience grew (81.5% in 2014 to 92.2% in 2022). Thirty-day mortality was 2.7%, stroke 1.2%, and reintervention under 1%. Patients who achieved procedural success had one-year mortality of 14.0% versus 26.7% in those who did not (HR 0.49).

The EVEREST II trial (5-year results, JACC 2015) randomized 279 patients (mostly degenerative MR) to MitraClip or surgery and showed more residual MR and higher early reintervention rates after TEER. By 5 years, mortality was similar. The trial used a first-generation device in a population that included many good surgical candidates; modern devices and patient selection produce better results.

The ongoing randomized trials (REPAIR MR, PRIMARY, MITRA HR) test TEER against surgery in older, lower-surgical-risk primary MR populations. Until they read out, the default for a patient in their 60s or 70s with primary MR and acceptable surgical risk is surgical repair at a high-volume center.

How Durable Is the Repair?

Durability depends on whether you achieve grade 1 or less residual MR at the end of the procedure. The EuroSMR registry showed that 85.5% of secondary-MR patients still had MR grade 2 or less at 5 years. Primary MR has higher recurrence rates, up to 41% in some series. Residual MR severity right after the procedure is the strongest predictor of long-term durability.

The 5-year EuroSMR data is the most comprehensive durability source. About half of secondary-MR patients remained at grade 1 or less. Recurrence and reintervention rates were 5 to 10% in the first months, stable through 3 years, and approximately 17% recurrence with 9% reintervention by 5 years. Primary MR has worse durability after TEER than secondary MR, a real consideration in patients with longer expected lifespan.

The single strongest predictor of long-term durability is the result on the table. Patients who leave the cath lab with grade 1 or less residual MR and a mean gradient at or below 5 mmHg have the best 5-year survival and freedom from reintervention. This is one reason TEER is best done at high-volume centers, the difference in procedural completeness between experienced and inexperienced operators is real and is reflected in long-term outcomes.

Who Is a Candidate for MitraClip?

For secondary MR, the COAPT phenotype: chronic severe secondary MR, persistent NYHA II–IV symptoms despite optimal guideline-directed medical therapy, LVEF 20–50%, LV end-systolic diameter ≤ 70 mm, pulmonary artery systolic pressure ≤ 70 mmHg, and suitable anatomy. For primary MR, patients at high or prohibitive surgical risk with suitable leaflet anatomy.

The 2020 ACC/AHA valvular heart disease guideline gives TEER a Class IIa indication in secondary MR meeting the COAPT phenotype. The phenotype is specific:

• Chronic severe secondary MR from LV systolic dysfunction
• Persistent NYHA Class II to IV symptoms on optimized medical therapy (ARNI, beta-blocker, MRA; SGLT2 inhibitor now considered foundational)
• LVEF between 20% and 50%
• LV end-systolic diameter ≤ 70 mm
• Pulmonary artery systolic pressure ≤ 70 mmHg
• Suitable leaflet anatomy on TEE (adequate leaflet length, no excessive calcification at the grasp zone, no severe mitral annular calcification, acceptable coaptation gap)

Optimization of medical therapy before TEER referral is essential, not a formality. In COAPT itself, only 2.2% of patients tolerated goal doses of all three foundational drug classes, reflecting how sick this population is at baseline.

For primary MR, the Class IIa indication is high or prohibitive surgical risk with suitable anatomy. Primary MR at low or intermediate operative risk should be referred for surgical mitral valve repair at an experienced center.

What Does the TEER Evaluation Look Like?

Evaluation for MitraClip is a multi-step process over 2 to 4 weeks: detailed history and exam, transthoracic echocardiogram to confirm severity and mechanism, transesophageal echocardiogram for leaflet anatomy, coronary angiography, and review in a multidisciplinary structural heart team that includes the cardiologist, interventional cardiologist, cardiac surgeon, imaging cardiologist, and often a heart failure specialist.

The TTE confirms severity and mechanism. The TEE is essential for procedural planning, leaflet length, tenting height, flail extent, calcification distribution, coaptation gap, and diastolic orifice area all determine whether a durable grasp is anatomically feasible. Some patients get a cardiac CT for additional anatomy. Coronary angiography is done if not recent, to identify obstructive disease that may need separate treatment.

The case is then reviewed by the structural heart team. The team weighs operative risk (STS, EuroSCORE), frailty, cognitive status, symptom severity, medical optimization, and anatomic suitability. The recommendation comes back as one of three: surgical mitral valve repair, transcatheter edge-to-edge repair, or continued optimization of medical therapy. The recommendation is presented to the patient in shared decision-making.

In my Encinitas practice, the heart-team process is not optional for severe MR considering intervention. The decision is multidimensional, and the right answer rarely comes out cleanly from a single perspective.

What Are the Risks of the Procedure?

Common procedural risks include femoral vein bleeding, atrial fibrillation, and acute kidney injury. Less common but important: stroke (~1% at 30 days), partial clip detachment requiring repositioning or surgery, iatrogenic mitral stenosis if the grasp narrows the valve excessively, and rare cardiac tamponade from the transseptal puncture. 30-day mortality in contemporary registries is under 3%.

The most common adverse events are mechanical: minor bleeding at the femoral access site (manageable with manual pressure or a closure device), transient atrial fibrillation (often self-limited after the transseptal puncture), and mild acute kidney injury related to contrast and procedure duration.

Less common but more consequential events include stroke (around 1% at 30 days), partial clip detachment from one leaflet (requiring a second clip, repositioning, or, rarely, conversion to surgery), iatrogenic mitral stenosis from an overly tight grasp, and cardiac tamponade from the transseptal puncture (rare). The atrial septal defect created by the transseptal puncture usually closes spontaneously or remains clinically insignificant.

Overall 30-day mortality in modern TEER registries is under 3%, with serious device-related events in roughly 1.4% of patients in COAPT.

What Does Recovery Look Like?

Hospital stay is 1 to 2 nights. Most patients walk the same day, return to light activity within a week, and feel near baseline within 2 to 3 weeks. Antiplatelet therapy (aspirin + clopidogrel) for several months in patients in sinus rhythm; patients in atrial fibrillation continue their existing oral anticoagulant. Follow-up echocardiograms before discharge, at 30 days, 6 months, and annually thereafter.

Recovery from TEER is much gentler than from surgical mitral valve replacement. There is no sternotomy and no cardiopulmonary bypass. The femoral access site needs a few days of restricted heavy lifting and no long drives, but walking is encouraged from day one. Most patients are back to work and normal activity within 1 to 2 weeks.

Antiplatelet management depends on rhythm. Patients in sinus rhythm typically take aspirin plus clopidogrel for several months and then aspirin alone. Patients in atrial fibrillation continue their existing DOAC or warfarin; the MitraClip does not require additional anticoagulation beyond what the rhythm already mandates.

Heart failure medical therapy should not be reduced after TEER. It is the foundation. The MitraClip builds on optimal medical therapy; it does not replace it.

How Should You Approach the Decision?

The best outcomes come from three things: the right patient (COAPT phenotype for secondary MR, high-risk primary MR for degenerative disease), the right team (a high-volume structural heart program with experienced interventional and imaging cardiologists), and the right goal (post-procedure grade 1 or less residual MR with a low mean gradient). All three together explain nearly every successful outcome I have seen.

For a patient with heart failure and severe secondary MR, the most important first step is full optimization of guideline-directed medical therapy. That means titrated doses of the four foundational heart failure drugs (ARNI or ACE/ARB, beta-blocker, MRA, SGLT2 inhibitor) to the extent the patient can tolerate them. If symptoms persist after real optimization and the echocardiogram shows severe MR out of proportion to LV size, TEER is one of the strongest positive interventions in modern cardiology.

For a patient with primary MR at low or intermediate surgical risk, the answer is surgical repair at an experienced center. For a patient with primary MR at high or prohibitive surgical risk, MitraClip is an excellent option, and the outcomes are better the earlier it is done after symptoms begin.

For a patient with “some leakiness” on an echocardiogram without symptoms and without severe grading, no procedure is warranted. The right care is surveillance with a cardiologist who reads the trajectory and acts when it changes.

Frequently Asked Questions About MitraClip and Severe MR

Who is a candidate for MitraClip?

The two main groups are patients with severe symptomatic secondary MR on optimized medical therapy meeting the COAPT phenotype (LVEF 20 to 50%, LV end-systolic diameter ≤ 70 mm, PA systolic pressure ≤ 70 mmHg, suitable anatomy), and patients with severe primary MR at high or prohibitive surgical risk. The decision is made by a multidisciplinary structural heart team.

Is MitraClip the same as mitral valve repair surgery?

No. MitraClip is a catheter-based procedure (transcatheter edge-to-edge repair, or TEER) performed through a femoral vein, with no sternotomy and no cardiopulmonary bypass. Surgical mitral valve repair involves open-heart surgery with the heart stopped on bypass. Surgery typically produces a more complete hemodynamic result, but MitraClip has a dramatically shorter recovery and is the right choice for high-surgical-risk patients.

How long does the MitraClip procedure take?

The procedure itself takes 2 to 3 hours under general anesthesia. Hospital stay is typically 1 to 2 nights. Most patients are back to light activity within a week.

Does MitraClip eliminate the leak completely?

Rarely. The realistic goal is to reduce severe MR to grade 1 or less with a low mean gradient. Patients who achieve grade 1 or less residual MR have the best long-term outcomes.

What is the difference between primary and secondary MR for MitraClip decisions?

Primary (degenerative) MR is a problem with the valve itself, most often mitral valve prolapse. Surgical repair at an experienced center is the gold standard at low or intermediate operative risk; MitraClip is reserved for high-surgical-risk patients. Secondary (functional) MR is a problem with the LV around an otherwise normal valve, usually heart failure. MitraClip is supported by COAPT for secondary MR meeting the COAPT phenotype.

How long does the MitraClip last?

At 5 years in the EuroSMR registry, 85.5% of secondary MR patients still had MR grade 2 or less. Primary MR has higher recurrence rates (up to 41% in some series). Residual MR severity at the end of the procedure is the strongest predictor of long-term durability.

What is the success rate of MitraClip?

Procedural success (residual MR ≤ mild with mean gradient < 10 mmHg) is 88.9% in the STS/ACC TVT Registry and has improved over time to about 92% at experienced centers. 30-day mortality is under 3%.

Will I need to take blood thinners after MitraClip?

It depends on rhythm. Patients in sinus rhythm typically take aspirin plus clopidogrel for several months and then aspirin alone. Patients in atrial fibrillation continue their existing DOAC or warfarin. The clip itself does not require additional anticoagulation beyond rhythm-based indications.

References

1. Stone GW, Lindenfeld J, Abraham WT, et al. Transcatheter Mitral-Valve Repair in Patients with Heart Failure (COAPT). New England Journal of Medicine. 2018;379(24):2307-2318.

2. Mack MJ, Lindenfeld J, Abraham WT, et al. 3-Year Outcomes of Transcatheter Mitral Valve Repair in Patients With Heart Failure. Journal of the American College of Cardiology. 2021;77(8):1029-1040.

3. Stone GW, Abraham WT, Lindenfeld J, et al. Five-Year Follow-up after Transcatheter Repair of Secondary Mitral Regurgitation (COAPT 5-year). New England Journal of Medicine. 2023;388(22):2037-2048.

4. Obadia JF, Messika-Zeitoun D, Leurent G, et al. Percutaneous Repair or Medical Treatment for Secondary Mitral Regurgitation (MITRA-FR). New England Journal of Medicine. 2018;379(24):2297-2306.

5. Grayburn PA, Sannino A, Packer M. Proportionate and Disproportionate Functional Mitral Regurgitation: A New Conceptual Framework. JACC: Cardiovascular Interventions. 2019;12(4):353-362.

6. Anker SD, Friede T, von Bardeleben RS, et al. Transcatheter Valve Repair in Heart Failure with Moderate to Severe Mitral Regurgitation (RESHAPE-HF2). New England Journal of Medicine. 2024;391(19):1799-1809.

7. Makkar RR, Chikwe J, Chakravarty T, et al. Transcatheter Mitral Valve Repair for Degenerative Mitral Regurgitation (STS/ACC TVT Registry). JAMA. 2023;329(20):1778-1788.

8. Feldman T, Kar S, Elmariah S, et al. Randomized Comparison of Percutaneous Repair and Surgery for Mitral Regurgitation: 5-year results of EVEREST II. Journal of the American College of Cardiology. 2015;66(25):2844-2854.

9. Stocker TJ, Hertell H, Orban M, et al. Durability of Mitral Valve Edge-to-Edge Repair in Secondary Mitral Regurgitation: The EuroSMR 5-year Outcomes. JACC: Cardiovascular Interventions. 2024;17(6):745-757.

10. Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. Journal of the American College of Cardiology. 2021;77(4):e25-e197.

11. Lim DS, Smith RL, Gillam LD, et al. Randomized Comparison of Transcatheter Edge-to-Edge Repair for Degenerative Mitral Regurgitation (CLASP IID). JACC: Cardiovascular Interventions. 2022.

12. Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Journal of the American College of Cardiology. 2022;79(17):e263-e421.