Edited by: Jan Van Der Heyden, St. Jan Hospital, Belgium
Reviewed by: Paolo Denti, San Raffaele Hospital (IRCCS), Italy; David Chistian Reineke, Clinic for Cardiovascular Surgery, Inselspital, Switzerland
This article was submitted to Structural Interventional Cardiology, a section of the journal Frontiers in Cardiovascular Medicine
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Mitral regurgitation is one of the most prevalent valvulopathies worldwide, and its surgical treatment is not feasible in all cases. The elderly and frail with several comorbidities and left ventricular dysfunction are often managed conservatively. Percutaneous treatment (repair or replacement) of the mitral valve has emerged as a potential option for those patients who are at a high risk for surgery. Mitral valve repair with the Mitraclip device proved both increased safety and mortality reduction in patients with severe mitral regurgitation. On the other hand, in the last decade, percutaneous mitral replacement opened new frontiers in the field of cardiac structural interventions. There are few mitral devices; some are in the early phase of development and some are waiting for CE mark of approval. The evolution of these devices was more complicated compared to the aortic technology due to the native mitral valve's complexity and access. This review aims to provide an overview of the current devices, their specific features, and their potential complications.
Opposite to transcatheter aortic valve replacement (TAVR), transcatheter mitral valve replacement (TMVR) is a much more complex procedure due to the mitral valve's anatomy and shape, lack of calcification, and its relationship with adjacent structures. An adequate pre-procedural study is mandatory and comprises of multimodality imaging to define mitral regurgitation, to evaluate a patient's eligibility according to anatomic characteristics, to plan the implantation access, and to identify possible issues during TMVR. There are few serious challenges such as mitral valve position, valve sealing, the proximity of the left ventricular outflow tract (LVOT), delivery system size, prosthesis anchoring, and valve thrombogenicity. Initial studies have shown encouraging results; nevertheless, the mortality at 1-year follow-up is high (
The present review aims to describe principal transcatheter mitral valves, focusing on their mechanism, anchoring design, and the potential complications that can occur during TMVR.
Mainly, the most frequent pathology on the mitral valve is mitral regurgitation (MR), which may be either degenerative or functional (
On the other hand, mitral annular calcification (MAC) is a degenerative process, affecting the fibrous base of the mitral valve, and its prevalence reaches 15% (
MAC may be associated with regurgitation or stenosis. Surgical treatment of this particular entity is complex due to the risk of potential complications such as intractable hemorrhage, ventricular rupture, or atrioventricular disruption, even for experienced cardiac surgeons (
Moreover, up to 25% of mitral bioprostheses present degeneration at 15-year follow-up (
In these scenarios (mitral regurgitation/stenosis in high-risk patients, MAC, and previous mitral replacement of repair), TMVR may play an important role, but extensive knowledge of the mitral valve anatomy is imperative and a rigorous screening should be done to evaluate the procedure feasibility.
The mitral valve apparatus is mainly composed of the mitral annulus, two leaflets, left atrium, left ventricle (LV), papillary muscles, and tendinous chords. Any disturbance of these components may determine mitral valve dysfunction.
The mitral annulus is rather a concept than an anatomical structure, and its characteristics are determinant for mitral valve replacement. The D shape with 3D geometry and size change with each cardiac cycle are just a few items that should be taken into consideration during transcatheter heart valve (THV) development (
Identifying suitable candidates for TMVR therapy has been a challenge for all devices. There are multiple exclusion criteria which can be clinical, anatomical, and/or device specific (
Published exclusion criteria for current transcatheter mitral valve replacement.
Tendyne (NCT02321514) | >70 mm | <30% | X | X | X | X | X | NA | |
Intrepid (NCT02322840) | NA | <20% | X | NA |
NA | NA |
NA | X | Severe renal insufficiency, and prior mitral valve surgery or intervention |
TIARA (NCT03039855) | NA | <20% | X | N/A | Area <2.0 cm2 at end-systole | NA | NA | X | Severe right ventricle dysfunction |
CardiaQ (NCT02722551) | NA | NA | X | X | NA | X | NA | NA | Previous aortic valve replacement |
Sapien M3 (NCT03230747) | >70 mm | <30 | X | X | X | X | NA | NA | NA |
Caisson (NCT02768402) | >70 mm | NA | X | X | X | X | NA | NA | Severe right ventricle dysfunction |
Highlife |
>70 mm | <30 | X | X | X | X | NA | NA | NA |
Fortis | NA | NA | X | X | X | X | NA | NA | NA |
CardioValve NCT03813524 | >75 | NA | X | X | X | X | X | X | NA |
Evoque | NA | <30% | X | X | Area <1.5 cm2 at end-systole | X | X | X | NA |
CT imaging is essential during pre-procedural planning for TMVR because it provides almost all the information needed to plan the procedure.
Specific measurements should be done for each component of the mitral valve apparatus.
Intercommisural, septal-to-lateral, trigone-to-trigone distance, and 3D perimeter are useful to size the adequate valve. Some of the devices rely on intercommissural distance such as the Tiara® valve (Neovasc Inc; Richmond, BC) (
A thorax CT scan can provide valuable data regarding the ideal intercostal space for the trans-apical approach and the angulation for coaxial deployment. Finally, an abdominopelvic CT scan provides information on ileo-femoral vein access in case of a transfemoral approach.
There are at least 16 devices developed for percutaneous mitral valve replacement. Most of these devices are in the early phase of development and do not have Food and Drug Administration (FDA) approval or the CE Mark (
Percutaneous mitral valves devices.
Transcatheter mitral valve devices.
Tendyne | Abbott | TA 34 Fr. | Apical tether | Outer (sealing) frame ranges 30–43 mm in the SL dimension and 34–50 in the IC dimension | 3.2 cm2 | Intra-annular | Fully recapturable system after complete deployment | D-shaped (outer stent) Circular (inner frame) | Nitinol, double frame; Self-expandable | Porcine pericardium, trileaflet |
Intrepid | Medtronic | TA 33Fr. | Radial force and sub-annular cleats | Inner stent−27 mm (Outer stent−43, 46, and 50 mm) | 2.4 cm2 | Intra-annular | No | Circular | Double stent, self-expanding, nitinol | Bovine pericardium, trileaflet |
TIARA | Neovasc | TA 32, 36 Fr. | 3 ventricular anchoring tabs (onto the fibrous trigone and posterior shelf of the annulus) | 35 and 40 mm | 6.5–12 cm2 | Intra-annular | No | D-shaped | Self-expanding, nitinol | Bovine pericardium, trileaflet |
CardiaQ | Edwards Lifesciences | TA/TF 33 Fr. | Mitral annulus capture with native leaflet engagement | 30 mm | NA | Supra-annular | No | Circular | Self-expanding, nitinol | Bovine pericardium, trileaflet |
Sapiens M3 | Edwards Lifesciences | TF/TA 20 Fr. | Nitinol dock system | 29 | NA | Intra-annular | No | Circular | Balloon-expandable, cobalt-chromium frame | Bovine pericardium, trileaflet |
Caisson | LivaNova | TF 31 Fr. | 4 sub-annular anchoring feet 3 atrial holding features | 36A 42A 42B | NA | Supra-annular | Recapturable/ retrievable | D-shaped | 2 components (anchor and valve); Nitinol, self-expandable. | Porcine Pericardium, trileaflet |
HighLife | HighLife SAS | TA39 Fr. (TF artery for loop placement) | External anchor; valve in sub-annular mitral ring | 31 mm | NA | Intra-annular | No | Circular | 2 components (ring and valve); Nitinol, self-expandable | Bovine pericardium, trileaflet |
Fortis | Edwards Lifesciences | TA 42 Fr. | 2 opposing paddles | 29 mm | NA | Intra-annular | No | Circular | Cloth-covered, self-expanding, nitinol | Bovine pericardium, trileaflet |
CardioValve | CardioValve | TF 28-Fr. | 24 focal “sandwiching” points | 3 sizes (range 40–40 mm) | NA | Intra-annular | No | Circular | Dual nitinol frame | Bovine pericardium, trileaflet |
Evoque | Edwards Lifesciences | TF 28-Fr. | External anchor | 2 sizes (44 and 48 mm) | NA | Intra-annular | No | Circular | Self-expanding, nitinol with fabric skirt to minimize paravalvular leak | Bovine pericardium,trileaflet |
There are four scenarios of mitral pathology treated with TMVR: (1) native non-calcified valves with severe mitral regurgitation, (2) native calcified valve (valve in MAC—Vi-MAC) with either mitral regurgitation or stenosis, (3) failed prosthetic ring and band (valve in ring, MViR), and (4) failed bioprosthesis (valve in valve—MViV). Specific devices were designed for the first scenario. For Vi-MAC, aortic THV devices and some of the mitral THV are currently used in compassionate use cases (
The Tendyne system (Abbott Structural, Santa Clara, California) is one of the specific THV devices designed for the mitral valve with the most significant worldwide experience. Nevertheless, so far, <1,000 valves have been implanted.
It is a unique valve-tether-pad design, with multiple valve sizes and profiles to address a range of pathoanatomy. The trileaflet porcine pericardial valve is mounted on a self-expanding nitinol double-frame stent and anchored to the left ventricle apex through a tether.
The inner stent is one size and circular to maintain an effective orifice area of >3.2 cm2, while the outer frame is D-shaped to conform with the shape of the mitral annulus (
The procedure uses a transapical approach, of which the site and the trajectory are determined by pre-procedural CT and intraoperative TEE imaging (
Finally, the SUMMIT trial (NCT03433274) is currently enrolling patients and is composed of three trial cohorts: randomized, non-randomized, and MAC. The subjects in the randomized cohort will be randomized in a 1:1 ratio to the trial device or the MitraClip system, and those in the non-randomized and MAC groups will receive the trial device.
The Intrepid™ system is probably the second most used mitral THV. It is composed of an outer stent frame (also called the fixation frame), which has a flexible atrial portion, allowing conformability with the native mitral annulus, and a stiffer ventricular portion, which is wider than the native annulus. The inner stent frame houses a one-size 27-mm trileaflet bovine pericardium valve, ensuring an effective orifice area of >2.4 cm2 (
The Tiara™ system (Neovasc Inc., Richmond, BC, Canada) is a new percutaneous transcatheter mitral trileaflet valve. It is mounted on a nitinol self-expanding platform presenting. The frame is D-shaped, with an atrial part composed of an asymmetric skirt, which provides anchoring and sealing characteristics. The principal mechanism of anchoring is provided by the three ventricular tabs, two anteriorly and one posteriorly (
As the Tendyne and the Intrepid, the Tiara valve is implanted through transapical access (left mini-anterior thoracotomy) under TEE and fluoroscopic guidance. After the LV puncture, a 0.035-in. J wire is advanced across the mitral valve into the left atrium and exchanged for a 0.035-in. Amplatz Extra-Stiff™ wire. The TIARA TMVR delivery system is inserted across the MV into the left atrium, and subsequently, the atrial skirt of the TIARA system is unsheathed. At this moment, 3D TEE is fundamental to orientate the valve and ensure a perfect anatomical alignment of the D-shaped device with the geometry of the MV annulus. Finally, the ventricular portion and the anchoring tabs are released with further unsheathing of the system. Re-sheathing, repositioning, and retrieval can be safely performed before the release of the ventricular skirt. After the deployment, the delivery system is re-sheathed and removed from the LV apex. The latest published data regarding the TIARA valve included 73 patients (22 patients were compassionate use cases) (
The CardiAQ-Edwards transcatheter mitral valve is the first THV implanted
The principal structure is a self-expanding nitinol frame with a 30-mm diameter at the inflow and 40 mm at the annulus, covering the native mitral annular dimensions from 36 to 39.5 mm. The frame presents two sets of opposing anchors, which will be engaged at the level of the native annulus and leaflets to secure the valve. The bioprosthesis contains a trileaflet valve from bovine pericardial tissue. Additionally, the valve presents two skirts (at the level of the inflow and the outflow aspects of the frame) to reduce possible paravalvular leaks (
However, the femoral–transseptal approach is much more complicated, requiring an arterio-venous loop and an inflated balloon advanced from the left atrium to the LVOT to ensure that the wire is not caught in the mitral apparatus. The arterio-venous loop helps to position the valve.
The initial study, First in Human (FIH), showed encouraging results (
Sapien M3 device is another transfemoral percutaneous mitral valve from Edwards. The valve is identical to aortic Sapien 3 29 mm, with the addition of an expandable polytetrafluoroethylene-covered nitinol “dock,” which encircles the chordae tendineae and native mitral valve leaflets, being the principal mechanism of anchoring (
The Caisson TMVR System, just as Sapien M3 and CardiaQ valves, is delivered
The HighLife System uses the “valve in ring” concept where the ring is implanted
First, a guidewire is advanced through the femoral artery (18-Fr introducer) into the left ventricle and is looped around the native valve leaflets (guided by TEE). A “ring” is placed over the guidewire and it serves to anchor and avoids the displacement of the valve into the left ventricle. The valve is coupled with the ring at the level of a groove in the annular region. This way, the native leaflets are trapped between the subannular implant and the prosthetic valve (
The available results include a cohort of 15 patients, with a technical success of 72.7% and procedure-related mortality of 18.2% (
The Fortis TMVR System is a cloth-covered self-expanding nitinol frame with a trileaflet bovine valve whose anchoring system consists of two opposing paddles, which must be placed in the A2-P2 area (
The Cardiovalve TMVR is a self-expandable valve, delivered through a 28-Fr introducer
The Evoque system is another mitral valve device delivered through transfemoral– transseptal access, designed by Edwards Lifesciences. It consists of a self-expanding nitinol frame and bovine pericardial leaflets. The ventricular outflow portion presents anchors used to engage the mitral leaflets and the subvalvular apparatus. The atrial inflow portion has a skirt to minimize paravalvular leaks. The delivery system allows the flexion to cross the interatrial septum and mitral valve, the depth control function ensures valve alignment, and the stabilizer stand controls the deployment. The initial experience was recently published, showing a technical success of 92.2% (13/14 patients) without any cardiovascular mortality at 30-day follow-up. The PVL was the main complication, requiring conversion to surgery in one case and percutaneous closure in other two cases. Moreover, there is also a concern regarding valve thrombogenicity since, in two of four patients with CT follow-up, hypoattenuated leaflet thickening with increased gradient was seen (
There are few devices in developing or preclinical studies. Three of them have had at least one First in Human case: The NaviGate (NaviGate Cardiac Structures Inc.) valve (
The AltaValve has a unique design and consists of a self-expanding supra-annular device, with a 27-mm bovine tissue valve mounted into a nitinol frame of spherical shape (50 to 90 mm), partially covered by a fabric skirt (
Other technologies such as the Cephea (Cephea Valve Technologies) system, AccuFit system (Sino Medical Science Technology, China), Saturn technology (HT Consultant, Switzerland), and MitrAssist Valve (MitrAssist Ltd., Israel) are still in preclinical studies.
Mitral annular calcification is a degenerative process, and its quantification has still not been validated. The presence of diffuse, almost circumferential heavy calcification of the mitral valve ring evaluated using CT was considered as severe MAC. Moreover, a total volume of 750 mm3 was also defined as severe MAC (
Mitral annular calcification may represent an intimidating surgical challenge during mitral valve surgery, and most of the patients with MAC are conservatively treated. Major bleeding, atrioventricular disruption, and ventricular rupture are just some of the fearsome complications. Moreover, patients with severe MAC are elderly and at a very high risk for surgery. Hypothetically, TMVR should be a less invasive procedure, but up to date, there are no specific devices designed for MAC. The aortic balloon–expandable valve may be used as off-label in MAC cases (
The mortality rate was 25% at 30-day and 53.7% at 1-year follow-up. The results should be interpreted with caution. These outcomes might have been related to patient selection (mean STS score of 15.3), and probably those patients were treated too late (>50% non-cardiovascular mortality). Almost all the survivors at 1-year follow-up experimented a clear symptoms improvement. The TMVR in MAC Global Registry also included a group of patients treated through the transarterial approach. Although much more invasive, this technique may have some advantages in cases that cannot be performed
Recently, Sorajja et al. (
Mitral valve repair is the elected treatment for patients with degenerative severe mitral regurgitation. Although the initial results are excellent, at 20-year follow-up, 15% of them present moderate–severe mitral regurgitation. In the last few years, patients at a high risk for re-surgery and failed mitral annuloplasty underwent transcatheter mitral valve implantation using percutaneous aortic valves, with acceptable results (
During the first 10 years after mitral valve replacement, up to 35% of patients may require a repeat operation (
The Mayval valve, of which the design is almost identical to the Sapien valve, could also be used for MViV. Although anecdotal cases were performed using this valve, there are no reports in the literature.
Although TMVR is a less invasive procedure than conventional mitral surgery, it presents several complications (
Follow-up after TMVR and complications.
Number of patients | 100 | 50 | 73 |
26 | 10 | 11 | 15 | 13 | 5 | 14 |
Mean Follow-up, mo | 13.7 | 7.04 | 1 | 1 | 1 | 9.9 | 12 | 24 | 12 | 1 |
Mortality (%) | 26/100 (26) | 11/50 (22) | 8/71 (11.3) | 7/26 (26.9) | 0/10 (0) | 2/11 (18.2) | 4/15 (26.7) | 7/13 (53.8) | 3 (60) | 1 (7.1) |
Cardiovascular mortality | 22/100 (22) | 11/50 (22) | 6/71 (8.5) | NA | 0/10 (0) | NA | NA | 5/13 (38.5) | 3 (60) | 0/14 |
NYHA III-IV | 10/86 (11.6) | 9/43 (20.9) | NA | NA | 1/9 (11) | 1/9 (11.1) | NA | 1/8 (12.5) | 1 (50) | 2 (18.2) |
Mean transmitral gradient mmHg | 3.0 ± 1 | 4.1 ± 1.3 | NA | NA | 6 | 3.1 | NA | 3 ± 1 | 3.4 ± 1.7 | 5.8 |
Moderate-severe MR | 0/100 (0) | 0/42 (0) | 0/9 (0) | NA | 1/9 (11) | 1/11 (9.1) | 0/12 (0) | 0/8 (0) | 0/5 (0) | 0/11 (0) |
Stroke | 3/100 (3) | 3/50 (6) | NA | NA | NA | 0/11 (0) | 0/15 (0) | 0/13 (0) | 0/5 (0) | 2/14 (14.2) |
Myocardial infarction | 4/100 (4) | 0/50 (0) | NA | NA | 0/10 (0) | 0/11 (0) | 0/15 (0) | 0/13 (0) | 0/5 (0) | 0/14 (0) |
HF hospitalization | 31/100 (31) | 12/50 (15.4) | NA | NA | 0/10 (0) | 1/11 (9.1) | NA | 2/13 (15.4) | 0/5 (0) | 0/14 (0) |
PM implantation | 7/100 (7) | NA | NA | NA | NA | NA | NA | NA | NA | 1 (7.1) |
BARC 2, 3, or 5 bleeding | 32/100 (32) | 9/50 (18) | NA | NA | 1/10 (10) | 0/11 (0) | NA | 2/13 (15.4) | 2/5 (40) | 3/14 (21.4) |
Device hemolysis | 3/100 (3) | 0/50 (0) | NA | NA | NA | NA | NA | NA | 0/5 (0) | 0/14 (0) |
Device embolization | 0/100 (0) | 0/50 (0) | 2/73 (2.7) | NA | NA | NA | NA | 0/13 (0) | 0/5 (0) | 0/14 (0) |
Device thrombosis | 6/100 (6) | 0/50 (0) | NA | NA | NA | NA | NA | NA |
0/5 (0) | 2/14 (14.2) |
Endocarditis | 2/100 (2) | 2/50 (4) | NA | NA | NA | NA | NA | NA | NA | 0/14 (0) |
LVOT obstruction | 1/100 | 0/50 (0) | 0/73 (0) | NA | NA | 0/11 (0) | 1/15 (6.6) | 0/13 (0) | 0/5 (0) | 1 (7.1) |
The Neo-LVOT area is the area that remains after mitral surgery or TMVR and decreases after all these procedures (
Moreover, the assessment of LVOT obstruction risk is based on CT measurements. A neo-LVOT area <250 mm2 at end-systole (
The specific design of the THV overcome in part to this potential complication: the Intrepid valve, due to its lower profile (height <18 mm), may be used even in “relatively contraindicated conditions” as prior prosthetic aortic valve replacement and with a smaller ventricular size; the Highlife valve, with its “valve in ring” design, allows to trap the native leaflets between the sub-annular implant and the prosthetic valve, which may prevent LVOT obstruction by pulling and fixing the anterior mitral leaflet instead of pushing it into the LVOT. The unique design of the AltaValve, with the only fixation at the atrial level, reduces to minimum the LVOT obstruction risk.
Moreover, different techniques were described to avoid or to treat LVOT obstruction during TMVR: alcohol septal ablation (
Alcohol septal ablation was performed as a bailout procedure in those patients with LVOT obstruction after TMVR implantation, with acceptable results (
The SCORPION procedure is a novel septal ablation technique (
The LAMPOON procedure emerges as a feasible technique to avoid LVOT obstruction during TMVR in those “contraindicated” cases. It is performed during TMVR implantation and consists of a controlled transcatheter laceration of the anterior mitral leaflet. Two guiding catheters are advanced using arterial femoral access and placed onto the left ventricle and left atrium, respectively. A stiff 0.014-in. guidewire (Astato XS 20, Asahi, Japan) is sheathed in an insulating polymer jacket (Piggyback Wire Convertor, Teleflex, North Carolina) and advanced from the LVOT to perforate through the center and the base of the anterior mitral leaflet using a short pulse of radiofrequency energy. Then, it is snared into the guiding catheter localized in the left atrium. The wire (electrified) is externalized, lacerating the AML by pulling on the two catheters. As a result, anterior mitral leaflet splays in diastole and coapts in systole. Khan
The BATMAN technique mimics the surgical approach called “translocation of the anterior mitral leaflet with chordal preservation,” with a less invasive access (
Patients who underwent Mitraclip with persistent residual or recurrent mitral regurgitation are challenging cases. Usually, these patients are not eligible for conventional surgery, and a THV is contraindicated due to the presence of a clip. However, a new transcatheter electrosurgery technique was reported and may allow for the selective laceration of failed Mitraclip and subsequent placement of a dedicated THV (
Bleeding occurs in 10–40% of patients after TMVR (
Hemolysis is a less frequent complication and may occur after TMVR in the presence of paravalvular leak as a result of turbulent flow pattern and erythrocyte destruction. The presence of hemolysis was described in three Tendyne cases (
The incidence of paravalvular leaks and hemolysis may be higher in MViR and Vi-MAC because the THV does not have the same shape as the native valve/mitral annuloplasty and gaps may remain in between. The treatment can be percutaneous or surgical. There are several cases which were successfully treated with AVP devices. Surgery remains the last option since the patients are at a high risk.
The endocarditis rate at 1-year follow-up was 4%, and it was reported in the Tendyne, Intrepid, and S3 MViV studies. Prophylaxis should be done as for regular bioprosthesis.
The experience with mitral bioprosthesis showed the need for oral anticoagulation after surgical mitral valve replacement for 3–6 months (
The antithrombotic treatment after TMVR is ambiguous since only three studies (
Moreover, the rate of valve thrombosis in the MViV and MViR groups may reach 15.4% (
The need for pacemaker implantation after TAVI is 10–30%. Nevertheless, there is no data in the field of TMVR. Hypothetically, it should be lower since no predilatation is needed, and the valve is placed far from the septum. The Tendyne registry reported 7% of pacemaker implantation, while the other studies did not mention it.
This phenomenon is mainly related to the imperfect match between the THV and the mitral annulus, previous bioprosthesis, ring, or band. Moreover, there are several THVs with a distinct site of anchoring: at the level of the mitral valve involving the leaflets or not and at the level of the apex or the left atrium. In the native valve, the absence of calcification and the D-shape makes perfect anchoring difficult. The only THV registries which reported delayed migration were TIARA I and TIARA II, which together presented a rate of 2.7% (
Currently, it was proven that the percutaneous transcatheter aortic valve replacement is feasible and comparable with surgical series, and the percutaneous transcatheter mitral valve replacement is just feasible for now. The development of mitral devices is a more complex process. The mismatch between mitral anatomy and prosthesis characteristics determine almost 60% of screening failure. From experience gained with fewer than 1,000 TMVR performed worldwide, we learned the following:
TMVR is an acceptable option for patients with mitral valve disease and who are at a high risk for surgery with a rate of technical success at >80%.
Mortality at 1-year follow-up is comparable with Mitraclip population, although it is high and mainly related to procedural complications.
The transapical approach permits “easy” valve deployment, with a higher risk of access bleeding.
During the first 3 months, anticoagulant treatment should be recommended to avoid potential complications such as valve thrombosis; nevertheless, the bleeding risk should be evaluated for each patient.
LVOT obstruction after valve implantation is the Achilles heel, and new techniques were described to overcome this fearsome complication.
The aortic THV for MViV, MViR, and Vi-MAC is feasible, with encouraging results at midterm follow-up.
Randomized trials comparing TMVR with traditional mitral surgery are ongoing, and their first results are expected at the end of 2021.
All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
MS is a consultant for Abbott Vascular. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.