Severe Mitral Regurgitation and the MitraClip: A San Diego Cardiologist's Guide

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 management, and for older, sicker patients the math often did not work. Today I sit with patients in my Encinitas office and walk them through a third option: a catheter-based procedure called transcatheter edge-to-edge repair, or 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 explains what severe MR is, how we grade it, what the MitraClip actually does, which patients benefit based on the landmark trials, and how I think about the choice between TEER, surgery, and continued medical therapy. I want you to leave this page able to ask your cardiologist the right questions.

The Short Version

Severe mitral regurgitation is a condition in which the mitral valve does not close properly and a large volume of blood leaks backward into the left atrium with every heartbeat. Over time that leak overloads the heart, raises lung pressures, and causes heart failure symptoms. The two main causes are primary (degenerative) MR, where the valve itself is diseased, and secondary (functional) MR, where the valve leaflets are structurally normal but cannot meet because the left ventricle has enlarged or scarred. MitraClip is a clip delivered through a vein in the groin that grasps the middle of both leaflets and pulls them together, reducing the leak. In the COAPT trial of patients with heart failure and severe secondary MR on maximal medical therapy, the MitraClip cut heart failure hospitalizations by roughly half and all-cause mortality by roughly a third at five years. In primary MR at prohibitive surgical risk, the MitraClip is now an established option, and ongoing trials are testing it against surgery in lower-risk older patients. Surgery remains the gold standard for most patients with primary MR at low or intermediate operative risk.

What the Mitral Valve Does and What Goes Wrong

The mitral valve sits between the left atrium and the left ventricle. It opens to let oxygenated blood fill the ventricle and then snaps shut when the ventricle contracts, so that blood is ejected forward into the aorta rather than sloshing backward into the lungs. It has two leaflets, the anterior and posterior, held in place by cords (chordae tendineae) tethered to small muscles on the ventricle wall (papillary muscles). The whole apparatus, plus the ring of tissue the valve sits in (the annulus), must work together. Damage to any component can cause the valve to leak.

In primary (also called degenerative) MR, the leaflets or their cords are themselves abnormal. The most common form is mitral valve prolapse with chordal rupture, often affecting the posterior leaflet. The leaflet flops back into the atrium during systole and blood escapes around it. In secondary (also called functional) MR, the leaflets and cords are normal. The problem is that the ventricle has dilated or scarred, usually after a heart attack or from nonischemic cardiomyopathy. The papillary muscles get pulled outward, the leaflets are tethered down, and they cannot meet in the middle. These are fundamentally different diseases with different treatments, even though the leak on the echo can look similar.

How We Grade Severity

Not every leaky valve needs treatment. Grading matters. On a transthoracic or transesophageal echo we measure several things: the size of the jet, the effective regurgitant orifice area (EROA), the regurgitant volume, the regurgitant fraction, the pressure in the pulmonary artery, and the size and function of the left ventricle and atrium. Severe primary MR is generally defined as EROA of at least 0.4 square centimeters, regurgitant volume of 60 mL or more, and regurgitant fraction of 50 percent or more, along with supporting features like a large flail leaflet or reversed pulmonary vein flow.

Secondary MR uses slightly different thresholds because the ventricle, rather than the valve, is the root problem. The American College of Cardiology and American Heart Association now use the same EROA cutoff of 0.4 for severe secondary MR, but they pay close attention to whether the leak is "disproportionate" to the ventricle size. This concept is important because it explains why some trials of MitraClip succeeded and others did not.

What the MitraClip Actually Is

The MitraClip is a small cobalt-chromium clip lined with polyester fabric. It is delivered through a catheter inserted into the femoral vein in the groin and advanced through the right atrium, across the atrial septum (a small puncture is made), and into the left atrium. Under transesophageal echo and fluoroscopic guidance, the interventionalist positions the open clip over the middle of the mitral valve, lowers it through the valve, grasps both leaflets at the center, and closes. The result is a double-orifice mitral valve with a strip of tissue in the middle holding the leaflets together. More than one clip can be placed if needed. The procedure takes two to three hours under general anesthesia, and most patients go home in one to two days.

The goal is not a perfect valve. The goal is to drop the severity of MR from severe to mild or moderate. That reduction, if durable, is what translates into fewer hospitalizations and better survival.

The COAPT Trial and Why It Changed Practice

The COAPT trial, published in the New England Journal of Medicine in 2018 with five-year follow-up published in 2023, is the single most important study in this space. It enrolled 614 patients with heart failure and moderate-to-severe or severe secondary MR who were still symptomatic despite maximal medical therapy. Patients were randomized to MitraClip plus medical therapy or medical therapy alone.

At two years, heart failure hospitalizations were reduced by 47 percent (35.8 percent per patient-year vs 67.9 percent, hazard ratio 0.53, p less than 0.001). All-cause mortality was reduced by 38 percent (29.1 percent vs 46.1 percent, hazard ratio 0.62, p less than 0.001). The number needed to treat to prevent one heart failure hospitalization was 3.1 over two years. The number needed to treat to prevent one death was 5.9. Those are striking numbers for any cardiovascular intervention, let alone one in a sick heart failure population.

The five-year follow-up confirmed the durability of the benefit. Heart failure hospitalization rates were 33.1 per 100 patient-years in the device arm versus 57.2 in the control arm (hazard ratio 0.53). All-cause mortality was 57.3 percent versus 67.2 percent (hazard ratio 0.72, 95 percent CI 0.58-0.89). The composite of death or heart failure hospitalization was 73.6 percent versus 91.5 percent (hazard ratio 0.53). Time alive and out of the hospital improved by roughly two months over the first two years. Device-specific safety events were rare, with 1.4 percent of patients experiencing them, all within 30 days.

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 we have outside of a transplant.

Why MITRA-FR Was Different

At almost the same time COAPT was reported, a French trial called MITRA-FR enrolled 307 patients with a similar question and reached the opposite conclusion. There was no difference in death or rehospitalization at one year. Understanding why these trials diverged is central to choosing the right patient for TEER today.

MITRA-FR enrolled patients with less severe MR on average (EROA 0.31 versus 0.40 in COAPT), worse left ventricular dilation, less uniformly optimized medical therapy, less MR reduction achieved with the clip, and more procedural complications. The central insight was this: in COAPT the leak was severe out of proportion to the ventricle size. In MITRA-FR the ventricle disease dominated, and fixing the valve did not fix the problem. The concept of "proportionate" versus "disproportionate" secondary MR came out of this divergence. It is not a bedside calculation. It is a framework, and it drives how we read the echo before we send a patient to the cath lab.

RESHAPE-HF2: Extending the Evidence

The RESHAPE-HF2 trial, published in the New England Journal of Medicine in 2024, tested TEER in patients with moderate-to-severe MR (mean EROA only 0.25, with only 14 percent of patients having EROA above 0.40). At 24 months, the composite of cardiovascular death or heart failure hospitalization was reduced (hazard ratio 0.65, 95 percent CI 0.49-0.85, p=0.002). Recurrent heart failure hospitalization rate ratio was 0.59 (95 percent CI 0.42-0.82, p=0.002). The number needed to treat to prevent one heart failure hospitalization was 5.1.

What RESHAPE-HF2 added is reassurance that the benefit of TEER extends to patients with moderate-to-severe secondary MR, not only the narrow COAPT severity profile. It does not mean every patient with a functional leak should be clipped. It does mean we have stronger evidence for a broader group than we did a few years ago.

Primary (Degenerative) MR: A Different Decision

For primary MR, the decision tree is different because mitral valve repair surgery is so good. In experienced centers, contemporary repair rates are around 94 percent and operative mortality is under 1 percent in roughly two-thirds of nonemergent cases. A successful repair can restore essentially normal life expectancy. Surgery remains a Class I recommendation for severe symptomatic degenerative MR and for many asymptomatic patients with preserved ejection fraction who are at low or intermediate surgical risk.

Where MitraClip fits in primary MR is for patients at high or prohibitive surgical risk. Data from the STS/ACC Transcatheter Valve Therapy Registry, which has tracked more than 19,000 patients with a median age of 82 and median STS score of 4.6 percent, show TEER is achievable in this older, higher-risk group. MR success, defined as residual MR of mild or less plus a mean gradient under 10 mmHg, was 88.9 percent. Procedural success rose from 81.5 percent in 2014 to 92.2 percent in 2022 as operator experience grew. Thirty-day mortality was 2.7 percent, stroke 1.2 percent, and reintervention under 1 percent. Patients who achieved MR success had dramatically better outcomes: one-year mortality of 14.0 percent versus 26.7 percent (hazard ratio 0.49) and heart failure readmission of 8.4 percent versus 16.9 percent (hazard ratio 0.47). The subgroup with mild or less residual MR and mean gradients of 5 mmHg or less did best, with one-year mortality of 11.4 percent.

A French nationwide analysis compared TEER to isolated mitral surgery and found lower cardiovascular mortality in the TEER arm at three years (hazard ratio 0.685, 95 percent CI 0.563-0.832, p=0.0001), though non-cardiovascular mortality was higher, reflecting the older and sicker population referred for the percutaneous approach.

TEER vs Surgery in Primary MR

The EVEREST II trial randomized 279 patients (predominantly degenerative MR) to MitraClip or surgery. TEER left patients with more residual MR and a higher need for subsequent surgical repair, especially within the first six months. By five years, mortality between the two arms was similar. An important nuance: beyond six months, subsequent surgical rates were nearly identical, suggesting that a TEER result that holds at six months tends to hold over time.

That said, EVEREST II was done with a first-generation device and in a population that included many patients who would be good candidates for surgery. Three ongoing randomized trials are testing TEER against surgery in older, lower-risk populations with primary MR: REPAIR MR (patients over 75 or at intermediate risk), PRIMARY (patients over 65 at any risk), and MITRA HR (high-risk). Those trials will reshape the primary MR decision tree in the next several years. Until then, for a patient in their sixties or seventies with primary MR and low operative risk, mitral valve repair surgery remains my recommendation.

Durability of the Repair

Every patient asks me, "How long will it last?" The EuroSMR registry followed patients out to a median of 5.4 years with serial echos. For secondary MR, 85.5 percent of patients still had MR of grade 2 or less at five years, and about half remained at grade 1 or less. Recurrence and reintervention rates were roughly 5 to 10 percent in the first few months, stable through three years, and then about 17 percent recurrence and 9 percent reintervention by five years.

Primary MR has higher recurrence rates than secondary MR after TEER. In some series, 41 percent of primary MR patients have either recurrence or reintervention by five years. Residual MR severity right after the procedure is the strongest predictor of durability. Patients who leave the cath lab with grade 1 or less residual MR have the best five-year survival. This is one reason I think about primary MR in older patients as a shared decision, particularly when surgery remains an option.

Who Is a Candidate: The COAPT Phenotype

For secondary MR, the American College of Cardiology and American Heart Association guidelines give TEER a Class IIa recommendation when the patient meets what is often called the COAPT phenotype:

The patient has chronic severe secondary MR from left ventricular systolic dysfunction, with persistent New York Heart Association Class II to IV symptoms despite optimal guideline-directed medical therapy. The echocardiogram shows a left ventricular ejection fraction between 20 and 50 percent. The left ventricular end-systolic diameter is 70 mm or less. The pulmonary artery systolic pressure is 70 mmHg or less. Anatomy is suitable for a durable grasp with the clip. Optimization of medical therapy before referral is essential. It is worth noting that in COAPT, only 2.2 percent of patients tolerated goal doses of all three guideline-directed medical therapy classes, reflecting how sick this population is with hypotension and kidney dysfunction on full therapy.

For primary MR, the Class IIa indication for TEER is patients at high or prohibitive surgical risk with suitable anatomy. Primary MR patients with low or intermediate operative risk should be offered surgery.

What the Evaluation Looks Like

A full evaluation for MitraClip is not quick. I usually frame it for patients as a multi-step process over two to four weeks. It starts with a detailed history and exam, a transthoracic echocardiogram to confirm MR severity and mechanism, and review of medication optimization. Most patients then need a transesophageal echocardiogram to look in detail at leaflet morphology, the tenting height and flail extent, leaflet length, calcification, the coaptation gap, the diastolic orifice area, and the location of the leak. Some patients get a cardiac CT to assess anatomy further. Coronary angiography is usually done if it has not been recently.

The case is then discussed in a multidisciplinary structural heart team, which typically includes the general cardiologist, the interventional cardiologist, a cardiac surgeon, an imaging cardiologist, and sometimes a heart failure specialist. The team looks at operative risk scores (STS, EuroSCORE), frailty, cognitive status, symptom severity, medical optimization, and anatomic suitability. The recommendation comes back as surgery, TEER, or continued medical management. My job as the patient's cardiologist is to translate that recommendation into plain language.

Risks of the Procedure

TEER is much less invasive than surgery, but it is not risk-free. The most common procedural risks are bleeding from the femoral vein access site, atrial fibrillation, and acute kidney injury. Less common risks include stroke (around 1 percent at 30 days), the clip partially detaching from one leaflet and needing repositioning or surgery, and creating iatrogenic mitral stenosis if the grasp narrows the valve too much. Cardiac tamponade from the transseptal puncture is rare but reported. Overall 30-day mortality in contemporary registries is under 3 percent. The procedure produces a small atrial septal defect that usually closes or becomes clinically insignificant over time.

What to Expect Afterward

Most patients stay one to two nights in the hospital. Recovery is faster than after surgery. There is no sternotomy, no cardiopulmonary bypass, and no long rehabilitation. Most patients are walking the same day, back to light activity within a week, and feeling near baseline within two to three weeks. Anticoagulation management depends on the underlying rhythm. Patients in atrial fibrillation usually remain on their existing oral anticoagulant. Patients in sinus rhythm typically take aspirin plus clopidogrel for several months, then aspirin alone.

Follow-up includes an echocardiogram before discharge, at 30 days, at 6 months, and annually after that. Heart failure medications should not be reduced after TEER. They are the foundation of the treatment, and TEER builds on that foundation.

What I Tell My Patients

If you have heart failure with reduced ejection fraction and severe secondary mitral regurgitation, the most important step is full optimization of your guideline-directed medical therapy. That means titrated doses of the four foundational heart failure drugs to the extent you can tolerate them. If you are still symptomatic after real optimization, and your echo shows severe MR out of proportion to your left ventricle size, TEER is one of the strongest positive interventions in modern cardiology.

If you have primary MR and you are at low or intermediate surgical risk, the answer for most patients is surgical repair at an experienced center. If you are at high or prohibitive risk, TEER is an excellent option and the outcomes are better the earlier we do it after symptoms begin.

If you are being told you have "some leakiness" on an echo without symptoms and without severe grading, you do not need a procedure. You need surveillance with a cardiologist who will track the valve with serial imaging and act when the trajectory changes.

I tell patients considering MitraClip that the best outcomes come from three things: the right patient, the right team, and the right goal. The right patient meets the COAPT or high-risk primary MR criteria. The right team includes an experienced interventional cardiologist and imager working together. The right goal is a post-procedure result of grade 1 or less residual MR with a low mean gradient. Those three in combination explain nearly every successful outcome I have seen.

When to See a Cardiologist

If you have been told you have a heart murmur that is new, louder, or associated with shortness of breath, fatigue, or exercise intolerance, ask for an echocardiogram. If you have an existing diagnosis of mitral regurgitation, your follow-up schedule depends on severity: moderate MR usually every one to two years, severe MR every 6 to 12 months with a cardiologist comfortable reading subtle changes. If you are developing new symptoms, the interval should shorten. In Encinitas and throughout San Diego, I see patients referred both for initial diagnosis and for second opinions on whether a mitral intervention is warranted. The decision should never feel rushed.

References and Further Reading

Stone GW, Lindenfeld J, Abraham WT, et al. Transcatheter mitral-valve repair in patients with heart failure. N Engl J Med. 2018;379:2307-2318 (COAPT primary results).

Mack MJ, Lindenfeld J, Abraham WT, et al. 3-Year Outcomes of Transcatheter Mitral Valve Repair in Patients With Heart Failure. J Am Coll Cardiol. 2021;77:1029-1040.

Stone GW, Abraham WT, Lindenfeld J, et al. Five-Year Follow-up after Transcatheter Repair of Secondary Mitral Regurgitation (COAPT 5-year). N Engl J Med. 2023;388:2037-2048.

Anker SD, Friede T, von Bardeleben RS, et al. Transcatheter Valve Repair in Heart Failure with Moderate to Severe Mitral Regurgitation (RESHAPE-HF2). N Engl J Med. 2024;391:1799-1809.

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

Benfari G, Sorajja P, Pedrazzini G, et al. Transcatheter edge-to-edge repair for severe mitral regurgitation in elderly high-risk patients. Eur Heart J. 2022;43:2055-2066.

Deharo P, Obadia JF, Bonnet G, et al. Transcatheter edge-to-edge mitral valve repair versus isolated mitral valve surgery: a nationwide cohort study. Eur Heart J. 2024;45:510-520.

Feldman T, Kar S, Elmariah S, et al. Randomized comparison of percutaneous repair and surgery for mitral regurgitation: 5-year results of EVEREST II. J Am Coll Cardiol. 2015;66:2844-2854.

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 Cardiovasc Interv. 2024;17:745-757.

Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. J Am Coll Cardiol. 2021;77:e25-e197.

Maddox TM, Januzzi JL Jr, Allen LA, et al. 2024 ACC Expert Consensus Decision Pathway for Treatment of Heart Failure With Reduced Ejection Fraction. J Am Coll Cardiol. 2024;83:1444-1488.

Hahn RT, Lindenfeld J, Lim DS, et al. Structural Cardiac Interventions in Patients With Heart Failure. J Am Coll Cardiol. 2024;83:832-847.