The Tendyne mitral valve is a transcatheter heart valve designed to replace a diseased mitral valve without open-heart surgery, and it is the only dedicated self-expanding transcatheter mitral valve replacement (TMVR) system that has earned both CE mark approval in Europe and FDA approval in the United States.1PubMed Central. Transcatheter mitral valve options for severe mitral annular calcification Built by Abbott (originally Tendyne Holdings), the device is aimed at people with severe mitral regurgitation who are too sick or anatomically unsuitable for conventional surgery. The technology sits at the frontier of structural heart intervention, and the clinical data are still maturing, so understanding what it does well, where the risks lie, and who stands to benefit most requires a close look at the evidence gathered so far.
How the Device Is Built
The Tendyne system uses a pair of self-expanding nitinol stents with a bioprosthetic valve sewn inside. The inner stent is circular, maintaining an effective valve opening larger than 3.0 square centimeters regardless of the patient’s anatomy. The outer stent is D-shaped, which lets it conform to the native mitral annulus, since that opening is oval rather than round. Sitting atop the stent assembly is an atrial flange that seals against the atrial side of the valve and anchors the device in place.2EuroIntervention. The Tendyne transcatheter mitral valve implantation system
What makes the Tendyne genuinely unusual among TMVR devices is a tether that extends from the prosthesis down to a pad on the heart’s apex. This apical tethering system does two things: it keeps the valve seated firmly against the mitral annulus, reducing the gap between the prosthesis and native tissue where blood could leak through, and it helps with sealing the surgical puncture at the apex after the device is delivered.3EuroIntervention. The Tendyne transcatheter mitral valve implantation system The prosthesis is also fully repositionable and retrievable during the procedure, meaning the implanting team can adjust placement or pull the valve back entirely if positioning is not ideal before committing to the final release.4PubMed Central. Early clinical results with the Tendyne transcatheter mitral valve replacement system
Who Is a Candidate
The Tendyne is not the first option for someone with a leaky mitral valve. It is reserved for patients with severe symptomatic mitral regurgitation who cannot safely undergo open surgical repair or replacement. In the Tendyne Expanded Clinical Study, 191 patients were treated, with an average age of about 74 years, roughly 63% male, and a predicted surgical mortality risk averaging close to 8%.5PubMed Central. Clinical outcomes and predictors of transapical transcatheter mitral valve replacement: the Tendyne Expanded Clinical Study These are patients who carry substantial comorbidities and for whom the standard surgical path would be prohibitively dangerous.
Many patients who receive a Tendyne have also been evaluated for transcatheter edge-to-edge repair (TEER), the clip-based approach that pinches the mitral leaflets together to reduce leakage. In a German comparison, patients directed toward the Tendyne system were more likely to have valve anatomy unsuitable for a clip and had higher rates of end-stage kidney disease requiring dialysis.6PubMed Central. Characteristics and outcomes of patients undergoing transcatheter mitral valve replacement with the Tendyne system In other words, the Tendyne tends to be offered to a sicker, more anatomically challenging population than those who get a clip. This distinction matters when comparing outcomes between the two approaches.
Pre-Procedure Planning and Imaging
Choosing the right valve size and predicting where it will sit inside the heart requires detailed imaging beforehand. CT scanning plays a central role in defining whether a patient is anatomically eligible, selecting the correct device size, planning the access route through the chest and apex, and simulating how the prosthesis will sit once deployed.7PubMed Central. Computed Tomography Planning for Transcatheter Mitral Valve Replacement One critical prediction is whether the new valve will push the native anterior mitral leaflet into the outflow path of the left ventricle, a complication discussed below. CT measurements help flag patients at risk for that problem and can guide strategies to prevent it.
During the implant itself, echocardiography guides the team step by step: confirming the catheter’s trajectory through the apex, checking that the valve is oriented correctly before release, and immediately evaluating whether there is any residual leak or obstruction after deployment. The combination of CT planning and real-time echo guidance makes this a procedure that depends heavily on a skilled imaging team, not just the interventional cardiologist doing the implant.
What the Outcomes Look Like
Across several registries and studies, the Tendyne achieves technical success, meaning the valve is delivered and positioned correctly, in roughly 94% to 97% of attempts. In the early SUMMIT trial experience of 100 high-risk patients, the technical success rate was 96% and 30-day mortality was 6%.8Society for Cardiovascular Angiography & Interventions. Clinical Trial to Evaluate the Safety and Effectiveness of Using the Tendyne Mitral Valve System for the Treatment of Symptomatic Mitral Regurgitation (SUMMIT) A European real-world registry reported a 95% technical success rate, with cardiovascular death at 7% by 30 days and 17% at one year; all-cause mortality reached 29% at one year.9PubMed. Transapical Mitral Valve Replacement: 1-Year Results of the Real-World Tendyne European Experience Registry
Longer follow-up paints a sobering picture. In a cohort of 100 patients followed for two years, all-cause mortality was 39%, and almost half of those deaths occurred in the first 90 days after the procedure.10PubMed. 2-Year Outcomes of Transcatheter Mitral Valve Replacement in Patients With Severe Symptomatic Mitral Regurgitation Those numbers look alarming in isolation, but context matters enormously. These patients were turned away from surgery because of how sick they were. Their expected survival on medical therapy alone would have been poor. The relevant question is not whether 39% mortality is high in absolute terms, but whether these patients lived longer and felt better than they would have without the valve.
One encouraging finding consistently reported across studies is the near-complete elimination of mitral regurgitation after implantation. The valve functioned as intended in the survivors, with no prosthetic dysfunction at one year in the severe annular calcification cohort and significant improvements in heart failure symptoms. Patients commonly jumped from severe functional limitation to much milder symptoms within months of the procedure.11EuroIntervention. Early outcomes of transcatheter mitral valve replacement with the Tendyne system in severe mitral annular calcification
The Apical Access Problem
Unlike most transcatheter aortic valve replacements, which enter through the femoral artery in the groin, the Tendyne system is delivered transapically, meaning through a small incision between the ribs and directly through the tip of the left ventricle. This approach gives the implanting team a straight shot to the mitral valve, but it also creates one of the device’s most significant risks.
Apical access complications occurred in about 6% of patients in one series of 127 procedures, and the consequences were severe: half of those patients died in the hospital, and the risk-adjusted odds of dying within 30 days were roughly 20 times higher when an apical complication occurred.12The Annals of Thoracic Surgery. Apical Access Management in Transapical Transcatheter Mitral Valve Replacement Critically, seven of the eight apical complications in that study occurred among the first ten patients at each center, suggesting a steep learning curve. As teams gained experience, the rate of serious access-site events dropped substantially. This is one of the clearest arguments for concentrating these procedures at high-volume, experienced centers rather than spreading them thinly across many hospitals.
Left Ventricular Outflow Tract Obstruction
When a large prosthetic valve is placed inside the mitral annulus, it can push the native anterior mitral leaflet toward the septum, narrowing or blocking the path that blood takes from the left ventricle into the aorta. This is called left ventricular outflow tract (LVOT) obstruction, and it can be life-threatening. Pre-procedure CT scanning flags patients at higher risk, but in some cases the anatomy makes obstruction likely regardless of how the valve is positioned.
For those patients, a complementary technique called LAMPOON, which involves intentionally lacerating the anterior mitral leaflet before or during valve deployment, can open up the outflow tract and prevent obstruction.13PubMed Central. LAMPOON to Facilitate Tendyne Transcatheter Mitral Valve Replacement LAMPOON splits the leaflet so it cannot create a wall against the septum. The technique adds complexity to an already complex procedure, but it expands the pool of patients who can safely receive a Tendyne.
Paravalvular Leak and Hemolysis
No transcatheter valve sits as snugly as a surgically sutured one. Small gaps between the prosthesis and native tissue can allow blood to leak backward, a problem called paravalvular leak. When blood is forced through those narrow, high-velocity jets, the shear forces can physically shred red blood cells, causing hemolytic anemia.14CASE. TAVR Treats LVOTO and PVL Following TMVR Transcatheter Aortic Valve Replacement to Treat Left Ventricular Outflow Tract Obstruction and Significant Paravalvular Leak Following Transcatheter Mitral Valve Replacement The hemolysis can range from a subtle laboratory finding to a severe clinical problem requiring intervention.
The Tendyne’s apical tether helps reduce paravalvular leak by pulling the prosthesis firmly against the annulus, but the problem can still develop, especially if the tether loosens or the valve shifts. One reported solution is valve retensioning, a procedure that adjusts the tether to reseat the prosthesis more tightly, which has successfully resolved both the leak and the hemolysis without needing another valve.15PubMed Central. Hemolysis After Transcatheter Mitral Valve Implantation Resolved by Valve Retensioning That the tether is adjustable after the initial implant is a practical advantage: it provides a built-in option for fine-tuning without a second major procedure.
Blood Thinners After Implantation
Clot formation on the prosthetic valve is a real concern after TMVR, and the risk appears to be higher than after transcatheter aortic valve replacement. Routine anticoagulation, typically warfarin or a similar blood thinner, appears necessary to keep the valve functioning properly and to reduce the chance of stroke or valve thrombosis.16PubMed. Thrombotic Risk and Antithrombotic Strategies After Transcatheter Mitral Valve Replacement This is worth knowing because many of these patients are elderly, prone to falls, and at baseline risk for bleeding, so the lifelong anticoagulation commitment is a meaningful trade-off. The optimal drug, dose, and duration are still being refined, and ongoing trials are expected to clarify best practices.
How Tendyne Compares to Edge-to-Edge Repair
Edge-to-edge repair (TEER), marketed mainly as the MitraClip or PASCAL system, is currently the most established transcatheter option for severe mitral regurgitation. It clips the mitral leaflets together to reduce leakage rather than replacing the entire valve. Comparing Tendyne to TEER is tricky because the two devices are not used in the same patients. As noted earlier, Tendyne recipients tend to be sicker, with worse kidney function and less favorable valve anatomy for a clip.
A study comparing the two approaches in patients with left ventricular dysfunction found that while both achieved comparable rates of successful implantation, reduction in regurgitation, and 30-day survival, TEER patients had lower rates of death and heart failure hospitalization at one year.17PubMed Central. Thirty-day and one-year outcomes following transcatheter mitral valve edge-to-edge repair versus transapical mitral valve replacement in patients with left ventricular dysfunction The authors acknowledged that this likely reflects the different risk profiles of the two groups rather than a straightforward superiority of one device over the other. TEER is the preferred approach when valve anatomy permits it; the Tendyne fills the gap for those whose anatomy does not cooperate.
Severe Mitral Annular Calcification
One of the most compelling use cases for the Tendyne system is severe mitral annular calcification (MAC), a condition where calcium deposits stiffen and distort the ring of tissue surrounding the mitral valve. MAC makes surgical repair extremely difficult because sutures cannot hold in calcified tissue, and it also makes clip-based repair unreliable because the leaflets are stiff and immobile. For decades, severe MAC with symptomatic mitral disease was something of a clinical orphan, with no good procedural option.
The SUMMIT-MAC study specifically evaluated the Tendyne in 103 patients with severe MAC and mitral regurgitation or stenosis. Technical success was about 94%, and 30-day mortality was roughly 7%. At one year, 60% of patients were alive and free of heart failure hospitalization, which significantly exceeded the pre-specified performance benchmark. Heart failure symptoms improved dramatically, with the proportion of patients in mild or no-symptom categories jumping from about 31% at baseline to nearly 88% at 12 months. Quality-of-life scores improved by an average of about 19 points on a standardized questionnaire, a clinically meaningful change.18PubMed. Transcatheter Mitral Valve Replacement for Severe Mitral Annular Calcification: Primary Outcomes From the SUMMIT-MAC Study For patients with severe MAC, these results represent a genuine shift in what can be offered.
An earlier, smaller series of 20 patients with severe MAC reported similar findings: successful implantation and discharge in all patients, complete elimination of regurgitation at one year in survivors, and functional improvement in 11 of 12 patients alive at 12 months, though all-cause mortality was 40% at one year.19EuroIntervention. Early outcomes of transcatheter mitral valve replacement with the Tendyne system in severe mitral annular calcification The high mortality reflects how sick these patients are, not a failure of the device itself. Among those who survived, valve function was excellent.
The Competitive Landscape
The Tendyne is not the only transcatheter mitral valve replacement system under development. The Intrepid (Medtronic) and Evoque (Edwards Lifesciences) systems have also shown promising results in early feasibility studies.20PubMed Central. Surgical versus transcatheter mitral valve replacement in functional mitral valve regurgitation However, the Tendyne holds a unique position as the only self-expanding TMVR system with both CE mark and FDA approval, and its transapical delivery route, while creating the access-site risks discussed above, enables treatment of some anatomies that transseptal or transfemoral routes cannot reach as reliably.21PubMed Central. Transcatheter mitral valve options for severe mitral annular calcification
The field is evolving rapidly. Newer-generation systems are exploring transseptal delivery (through a puncture between the atria), which would eliminate the apical access problem entirely. Whether those systems will match the Tendyne’s effectiveness in complex anatomies like severe MAC remains to be seen. For now, the Tendyne’s head start in regulatory approvals and its growing evidence base give it a practical advantage in the clinic.
Cost-Effectiveness
Transcatheter mitral valve replacement is expensive. The device itself, the hybrid operating room, and the multidisciplinary team required drive costs well above those of medical therapy alone. An economic analysis from Poland found that the Tendyne system was cost-effective compared to medication-only management when accounting for survival gains, quality-of-life improvements, and reduced heart failure hospitalizations. The incremental cost was well below Poland’s official cost-effectiveness threshold.22PubMed Central. Transcatheter mitral valve replacement – a new option for a selected group of patients? Cost-effectiveness analyses are always context-dependent, and figures from one country’s healthcare system do not translate directly to another’s. But the general finding, that replacing the valve is a reasonable use of resources compared to leaving these patients on medications that do not fix the underlying leak, supports the case for making the technology available.
Open Questions About Long-Term Durability
Like all bioprosthetic valves, the Tendyne uses treated animal tissue (porcine pericardium) for its valve leaflets. Surgical bioprosthetic mitral valves typically last 10 to 20 years before the tissue degenerates and the valve starts leaking or stiffening. Whether the Tendyne’s leaflets will hold up as well over similar timeframes is genuinely unknown. The device has only been implanted in humans since 2014, and most of the patients who have received it are elderly with limited life expectancy, so decades-long durability data will take a long time to accumulate. For a 75-year-old patient with serious comorbidities, whether the valve lasts 15 years is largely academic. But if the Tendyne’s use expands to younger or less sick patients in the future, durability will become a much more pressing question.
Another unresolved issue is what happens if the bioprosthetic valve does eventually fail. Surgical bioprosthetic valves can sometimes be treated with a valve-in-valve transcatheter procedure, where a new valve is placed inside the old one. Whether the Tendyne’s geometry and tether design will accommodate a valve-in-valve approach is something engineers and clinicians are actively considering but have not yet tested in large numbers. The retrievability of the Tendyne during the initial implant is a design strength, but retrieving a calcified, tissue-ingrown prosthesis years later would be a fundamentally different challenge.