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NEW YORK CITY -- Recent device approvals officially put transcatheter tricuspid valve intervention (TTVI) on the map for symptomatic severe tricuspid regurgitation (TR), though workforce challenges and a less-than-compelling evidence base stand in the way of broad adoption.

Currently, the hospitals allowed to offer TTVI technology are slowly expanding from those that had participated in the clinical trials to other sites chosen by industry, according to Susheel Kodali, MD, of New York-Presbyterian/Columbia University Irving Medical Center in New York City.

A major barrier to greater dispersion of TTVI is its heavy reliance on imaging by an experienced interventional echocardiographer to ensure that the right patients are treated.

Compared with transcatheter aortic valve replacement (TAVR), "TTVI requires a different and more complex skillset," Kodali explained at the New York Valves meeting, the successor to the annual TVT conference previously hosted by the Cardiovascular Research Foundation (CRF).

Meanwhile, he added, poor compensation and scarce training opportunities limit the number of echocardiographers with the right skillset. The challenge of the future is that "after initial sites are opened, industry will be pressured to open lower-volume sites that may not have the skillset required unless site requirements are more clearly defined," Kodali predicted.

Fair and appropriate dissemination of the technology should be another concern, panelists suggested.

"When an individual sponsor gets to be the final arbiter on site selection, then so many other things come into play," said session co-moderator Martin Leon, MD, also of New York-Presbyterian/Columbia. He suggested a good relationship with device makers, by consistent use of their products, as a potential factor in who gets their hands on TTVI.

"It's not going to be the kind of dispersion that's going to be fair and noncompetitive," Leon warned.

"Ensuring geographical diversity will be a challenge initially and many patients may not have access to the therapy," Kodali added.

In TR, the tricuspid valve leaflets do not close completely during systole, causing blood to regurgitate from the right ventricle into the right atrium. Due to a typically older, sicker profile, affected patients have historically had few treatment options outside high-risk surgery.

Responding to this unmet need of patients, the FDA approved the Evoque tricuspid valve replacement system as the first transcatheter treatment for TR this past February. The approved indication -- specifically for the improvement of health status -- was based on 6-month results from the TRISCEND II trial that supported Evoque's effectiveness in reducing TR and improving functional and quality of life (QOL) outcomes on win-ratio analysis.

FDA approval for the TriClip G4 device's transcatheter edge-to-edge repair (TEER) -- similarly for improving QOL and functional status -- followed . Agency advisors had been nearly unanimous in backing the TriClip G4 for severe TR based on the TRILUMINATE trial, which showed the device was safe and technically met the superiority composite endpoint at 1 year on win-ratio analysis, albeit through symptom improvement alone.

This makes two TTVI devices that made it to the market as FDA breakthrough-designated therapies despite no proven reductions in hard outcomes such as mortality.

"It's not clear that breakthrough designation is beneficial to patients, physicians, or device manufacturers," argued David Cohen, MD, MSc, of CRF and St. Francis Hospital in Roslyn, New York.

"The field of structural heart disease has benefitted tremendously from foundational trials that have shown unequivocal clinical benefits (e.g. [for TAVR], COAPT [for mitral valve TEER]). When the foundational trials are less definitive, there is a risk that the entire field rests on a shaky foundation," he continued. "And you know what happens with these devices, it's not great for the manufacturer because they don't get paid for."

It is also unclear which subsets of patients are more likely to achieve moderate or less TR after TTVI.

During an earlier morning session at New York Valves, Brian Whisenant, MD, of Intermountain Medical Center Heart Institute in Murray, Utah, reported that the safety and efficacy of TriClip still applied across a broad range of anatomies -- including four or more valve leaflets, large coaptation gaps, and right ventricular lead placement -- based on TRILUMINATE and single-arm cohorts.

However, session discussant Paul Grayburn, MD, of Baylor Scott & White The Heart Hospital in Plano, Texas, warned of selection bias with this kind of analysis, as participants were the patients that operators thought had a good chance of a good result in the first place.

The importance of good echocardiographers was reiterated by Kodali during his presentation later that afternoon.

Grading TR severity is notoriously challenging due to the heterogeneous nature of the condition, as some people present with prior left heart surgery or pacemakers, atrial fibrillation, pulmonary hypertension, or right heart dysfunction. This makes it easy to overestimate TR severity, he suggested.

Fellow panelist and expert echocardiographer Rebecca Hahn, MD, also of New York-Presbyterian Columbia, shared that the American Society of Echocardiography is hoping to be able to certify imagers that are qualified to do these complex procedures and get the compensation to allow the tricuspid field to progress.

In contrast, the cardiovascular societies are not likely to go the route of certifying individual physicians, leaving that to industry, Leon predicted.

Interventionalists new to TTVI are known to face a steep learning curve themselves. Newcomers relying on procedural technical training from industry aren't getting training on the disease or patient management, said Leon. "They just train them on being able to do a procedure using a specific device."

"So the system right now is somewhat broken," he complained.

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