The biggest tricuspid study presented at ESC Congress 2023 was TRI-SCORE, which evaluated a tricuspid risk scoring system to determine the best time to intervene on patients. It also compared the performance of tricuspid valve surgery and transcatheter tricuspid valve repair using transcatheter edge to edge repair (TEER). More than 2,400 patients were enrolled in the TRIREGISTRY for this study and followed for two years to assess outcomes. They were divided in to three cohorts based on treatment strategy: medical therapy only, surgical interventions and transcatheter interventions. 

Von Bardeleben said the lower a patient's score, the better their outcomes were. Survival in the surgical and transcatheter arms of the study were both very good for patients with lower scores. 

Tricuspid surgical and transcatheter outcomes are both improving

Historically, tricuspid surgical repair and replacement have had poor outcomes, but von Bardeleben said techniques have changed and outcomes are improving. 

"We know at highly experienced centers like the Mayo Clinic, and some high volume centers in Europe that do beating heart surgery, the outcomes have actually been better than what is reported generally in national registries. In-hospital mortality for surgery according to registries is between 9-12%. In the higher volume centers, mortality drops down to about 6%. The in-hospital mortality for transcatheter methods is about 0.6-1.3%, so even more beneficial," von Bardeleben explained.

However, he said use of tricuspid devices is new and there is a learning curve associated with using them, Like it is with any medical device, operators get better using the technology over time. This is especially true in the U.S. and other countries where transcatheter devices do not have regulatory clearance, so they are only being used for the first time in trials.

Single-leaflet device attachment (SLDA) complications are one of the more serious issues encountered during these procedures. This is what happens where there is a complete loss of connection between the clip and one of the leaflets. He said inexperienced operators see this happen in about 7% of cases. In more experienced centers, SLDA is down to about 3.5%, which mirrors what was seen with MitraClip cases early on in that device's adoption period. 

"It is expected that the detachment rates will decline below 3% in the very near future," von Bardeleben said.

Overall, he said both surgical and transcatheter techniques achieve their primary goals in about 70% of cases. 

Any tricuspid functional improvement helps patients

Evidence in recent studies for tricuspid valve interventions show that any reduction of regurgitation usually results in a noticeable improvement in patient symptoms. He echoed comments from other tricuspid structural heart experts that interventions do not have to be perfect, and some residual regurgitation is acceptable. 

The tricuspid value is often compared with the mitral valve, but it is a different animal functionally. Von Bardeleben said patients can tolerate levels of regurgitation that would kill a patient if those same levels were seen in the mitral valve. The higher TR levels have earned it an extra regurgitation classification levels beyond the mitral classes of mild, moderate and severe. TR has the additional levels of massive and torrential that are not see in the mitral valve.

He said overall the goal of therapy is to get patients to moderate or below, or to reduce their regurgitation by two grades. With patients with very high amounts of tricuspid regurgitation, just reducing it a little can help the patients feel much less symptomatic.

"There is benefit for patients that move just from torrential to severe and not even reaching moderate, and it is better than not treating the patient," von Bardeleben explained. 

He said it is best if a therapy can reduce regurgitation by two or three grades. Ideally, interventions probably need to be done in less sick patients before they progress to the massive and torrential grades, so studies are needed to show if this is the case and to better understand when to intervene. 

This helping patients feel better has also translated into lower hospital readmission rates in the recent tricuspid intervention trials. 

"The hospitalization rate in our first TRILUMINATE single arm study was 1.3 per year and we reduced it to 0.6, which was a massive reduction for the patients. But in the bRIGHT trial, it was only 0.5, and in the randomized trial, is was 0.25," von Bardeleben said.

Improving hemodynmaic function also has positive effects elsewhere in the body.

"I think a lot of cardiologists have been skeptical in the beginning about a the use of a treatment in tricuspid. But we are seeing that there are clear benefits. We have benefits in renal function, we have benefits in the cardio-hepatic syndrome, and we have benefits in the patient's everyday life," he explained. 
  
Von Bardeleben also said research in congenital heart disease has shown interventions on the right side of the heart in the tricuspid or the pulmonary valve really increases cardiac output; that is what allows for the secondary outcomes being seen in tricuspid trials now.

Tricuspid heart surgery was not widely used in the past because of the higher rates of poor outcomes, but the lower complication rates and minimally invasive nature of transcatheter procedures peaked interest and may could significantly improve TR among patients, which is considered a widely underdiagnosed condition.

"Patients were only treated surgically in about 0.5% to 1.5% of cases if they had an indication in the past, so the introduction of transcatheter procedures should increase the availability of treatment. I expect there will be a five-fold to 10-fold increase over time as we gain more and more evidence on the benefits of such therapies," von Bardeleben said. "Seeing more and more benefits as study evidence is evolving, I could foresee there being an increase in the number of transcatheter tricuspid interventions. We always need to think about the risk/benefit ratio for the patient, and as the risk is definitely going down with transcatheter methods, I think the benefit for the patient is easier to reach."

The success of mitral valve interventions and early successes of tricuspid valve interventions in recent years jave greatly boosted the number of patients entering tricuspid valve trials. Today, von Bardeleben said there are many more patients enrolled in tricuspid studies than there were during the early days of mitral interventions.

Increasing numbers of pacemaker patients are being treated for tricuspid regurgitation

One of the issues frequently discussed in sessions at cardiology conferences on tricuspid valve interventions is how to work around the leads that go through the tricuspid valve if a patient has a pacemaker. In the beginning of studies investigating transcatheter treatments for TR, only small numbers of patients with pacemaker leads were included as investigators took a conservative approach. However, as operators have grown more comfortable and better understand how to work with or around leads, that number has increased.

Von Bardeleben said one of the initial leaflet clipping studies only included about 13% patients with pacemaker leads through the valve. And even then, only patients with leads in the posterior commissure were allowed, because they were considered outside of the clipping area. But in the more recent bRIGHT trial for the Abbott TriClip, the number of patients with leads increased to 30%. He said this shows increasing levels of comfort working around leads. The complication rate in the bRIGHT study was also below 1%. He noted this complication rate is a lower rate than lead extraction if they removed the leads first so they could perform the valve procedure. 

"Most people with pacemakers can still be treated even though the leads may be the cause of the regurgitation. But a leaflet coaptation device may be able top change the tricuspid valve for the better without the need for removing the pacemaker. I would say for a low number of maybe 5%, we may still have to remove the pacemakers and then we can go for modern, leadless pacemakers.