Mitral valve innovations

The mitral valve has long been a challenging target for transcatheter interventions due to its complex anatomy and diverse failure modes. Despite the success of the MitraClip in addressing mitral regurgitation over the past nine years since FDA clearance, the field has been slow to commercialize additional solutions. Grubb emphasizes that a one-size-fits-all approach is unlikely to work.

"The first MitraClip procedure was in 2002, the same year as the first TAVR. We haven't made as much progress. This is because of the diversity of ways a mitral valve fails," Grubb said. 

She believes a variety of tools are needed in the toolbox to be able to treat the atrial valve with minimally invasive approaches. 

One promising development in the mitral valve space is the emergence of newer replacement technologies. These innovations build upon lessons learned from previous failures the past several years, with a focus on creating better-designed valves that can adapt to the dynamic nature of the mitral annulus. While progress is being made, it is acknowledged that it will be a long road before these technologies reach the market.

"I'm actually really excited about some of the newer mitral replacement technologies as we've learned from the failures as well. I'm really encouraged that with some of the newer designs and the thinking around it. Fortunately, what we learn from a lot of those mitral devices is that with just a small bit of engineering, they actually work in the tricuspid space," Grubb explained.

Tricuspid valve advancements

In contrast to the mitral valve, the tricuspid valve has seen remarkable progress in transcatheter interventions. It is sometimes referred to as the "forgotten valve" because often it is not treated for stenosis or regurgitation due to historically poor surgical outcomes and a lack of options. But that is now all about to change as cardiology is clearly gearing up with conferences on new approaches to treat the tricuspid valve. Early trial results have shown very good improvements in quality of life in these patients, who often present with right side heart failure.  

"The tricuspid valve has presented a lower surgical bar, making it more accessible for innovation. Patients suffering from tricuspid regurgitation have limited treatment options, and even modest improvements in their quality of life can be considered a significant success," Grubb explained.

The TRILUMINATE trial, for instance, has demonstrated that tricuspid leaflet clips can lead to substantial reductions in regurgitation and a notable improvement in patients' overall well-being, despite not showing a difference in death rates or rehospitalization. Unlike the aortic and mitral valves, the goal of treatment is not to eliminate the valve regurgitation, but to improve the patient's quality of life.

This is a big shift in terms of perspective, and the focus is actually enhancing patients' daily lives.

"The patients feel better. For me, that was the win. So that's oftentimes what we look for in heart failure trials, so maybe instead of thinking about just the tricuspid valve, we have to think about treating heart failure with these devices," Grubb said.

Timing interventions and surgery have been the handicap in tricuspid valve care

The main issue for poor outcomes in tricuspid interventions may be the timing of treatment. Patients often receive interventions too late, when they have already developed severe right-sided heart failure. Grubb said this likely led to poor outcomes in trials for surgery in the past and if surgery was performed when the patient was healthier, the results might have been much different. 

Grubb said this mirrors the historical experience with aortic valve interventions, where earlier treatment has shown better outcomes. Addressing tricuspid valve disease at an earlier stage could dramatically improve results and transform the field.

"I think in the past there was never a huge commitment to the treatment of tricuspid regurgitation or tricuspid valve disease other than in patients with endocarditis. Oftentimes, we were getting the patients so late. And so if somebody has hepatic congestion from their tricuspid valve, we have waited too long. And I think that's going to possibly be the Achilles heel to a lot of the tricuspid trials is that we're not intervening early enough," Grubb stressed. 

A similar issue with timing of procedures was realized with the aortic valve, which has led to the TAVR trials focused on low-risk and asymptomatic patients with moderate to severe aortic stenosis that are happening now. 

"If we intervene earlier, do the patients do even better? I think that it's going to be a good lesson, because I am suspicious that in the surgical literature, the reason that our tricuspid patients did so poorly was because we were really dealing with in-stage, tricuspid valve disease and end-stage right-sided heart failure. We just needed to get to them earlier and our results would've been dramatically different, in my opinion," Grubb said. 

Two late-breaking trials for mitral and tricuspid valves at TCT

The late-breaking data from the Tendyne SUMMIT pivotal trial included results from the study roll-in and mitral annular calcification (MAC) arm for the Tendyne transcatheter mitral valve replacement (TMVR) system. The data for the first 100 patients showed 100% procedural survival, few procedural complications, and mitral regurgitation elimination sustained through one year. The data also show improved heart failure symptoms and quality of life at one year.

Early outcomes of 103 subjects using a transapical TMVR system for severe MAC and MR/mitral stenosis showed procedural success was high with a 30-day mortality rate of 6.8%. MR elimination (100% mild or less) was associated with meaningful changes in cardiac output and forward stroke volume, with reduced heart failure symptoms. 

The second study was the TRILUMINATE pivotal trial for the Abbott TriClip, a modified version of the MitraClip, to treat tricuspid regurgitation (TR). The primary cohort analysis results were first presented at the ACC.23. At TCT, the outcomes of all randomized and the single-arm patients with tricuspid TEER were reported. Despite the complex anatomies present in the single-arm cohort, outcomes between single-arm and randomized cohorts were comparable, including 30-day safety, sustained TR reduction, and 12-month improvements in KCCQ-OS scores.