First-In-Human Transcatheter Tricuspid Repair Feasible But Questions Remain

High-risk patients with severe tricuspid regurgitation who undergo repair of the tricuspid valve using a novel transcatheter system have a significant reduction in regurgitation severity, an improvement in functional status, and a reduction in peripheral edema, according to the results of a small first-in-human study.

Published December 8, 2015, in the Journal of the American College of Cardiology, the study results suggest the percutaneous approach might one day be a treatment option for patients unable to undergo tricuspid-valve repair surgery or those considered high risk for surgery who are refractory to medical therapy.

In 7 patients with severe tricuspid regurgitation who had been declined for surgery, transcatheter repair using the Forma system (Edwards Lifesciences) led to an intraprocedural improvement in regurgitation severity, with 3 patients classified with moderate regurgitation and 4 patients classified with mild regurgitation. At 30 days, there were no reported access-site or device-related complications.

To TCTMD, study author Christopher Thompson, MD, of St. Paul’s Hospital (Vancouver, BC), said tricuspid regurgitation has not always been seen as a priority for physicians and surgeons.

“In the old days, tricuspid regurgitation was viewed as a nuisance and wasn’t thought to do anything bad but we now know that isn’t true,” said Thompson. “There is a negative impact on quality and quantity of life by having bad tricuspid regurgitation.”

How to Treat Isolated Tricuspid Regurgitation

The largest population of patients with tricuspid regurgitation are those who have had another procedure, usually mitral valve surgery, but who did not have their tricuspid valve repaired at the same time, explained Thompson.

“Old dogma was that if the tricuspid valve leaflets looked normal, and the regurgitation didn’t look too bad, if you fixed the mitral regurgitation then the tricuspid valve would probably be okay,” he said. “But if you saw pathology on the tricuspid leaflets, then the thinking was that you should probably fix that at the time of [mitral-valve] surgery.”

Valentin Fuster, MD, PhD, of Mount Sinai Hospital (New York, NY), the editor-in-chief of JACC, echoed that sentiment in a podcast accompanying the study, calling the tricuspid valve the “forgotten valve.” More than 80% of tricuspid regurgitation, he said, is secondary to left-sided heart disease that causes right-ventricular volume/pressure overload. He added that more than 20% of patients undergoing surgery for left-sided valvular disease present with significant tricuspid regurgitation.

“It’s a very common issue,” said Fuster. For patients undergoing left-sided valve surgery, concomitant tricuspid valve repair is recommended in the presence of severe tricuspid regurgitation. “Even mild-to-moderate tricuspid regurgitation should probably be fixed at the time of valve surgery,” he advised.

Fuster noted that if tricuspid regurgitation develops or persists after mitral-valve surgery, reoperation carries a high risk for cardiac and extracardiac conditions, leaving physicians in a tough spot about how to treat these patients.

Complicating Factors

The Forma transcatheter-based system is designed to reduce tricuspid regurgitation by occupying the orifice area and providing a surface for native leaflet coaptation. The system has a cylindrical, foam-filled polymer “spacer” that fits across the tricuspid valve and is then anchored to the apex of the right ventricle. A locking system in the left subclavian vein also keeps the spacer in place.

In the feasibility study, the 7 high-risk, surgery-ineligible patients all had severe tricuspid regurgitation and clinical signs of heart failure. Average patient age was 76 years, and the mean EuroSCORE was 26%.

The device was implanted without procedural complications, and the median length of hospital stay was 4 days. As noted, tricuspid regurgitation was reduced intraprocedurally in all patients. At 30 days, 6 of the 7 patients showed functional improvement—moving up to NYHA class II heart failure—with a corresponding reduction in peripheral edema. Diuretic dosage was reduced in 2 patients.

Thompson told TCTMD that while he was impressed with the feasibility study, a number of questions remain about the technology. For example, while the researchers were able to assess improvements in regurgitation severity, echocardiographic endpoints are not ideal, he observed.

“None of hemodynamic measurements are designed to figure out the volume flow across the valve when it has the spacer stuck in the middle of it,” said Thompson. “We’ve created these quite narrow spaces for blood to flow between the spacer and the leaflets and because they are relatively narrow and they have relatively higher velocities, [this] makes it look more impressive when it hits the atrium.”

While the echo criteria are weak for assessing an improvement post-procedure, evaluating patient symptoms can be just as problematic, Thompson noted, stressing that tricuspid regurgitation is extremely volume-sensitive and amenable to medical therapy. Because the thin-walled right ventricle is easily distensible, a little bit of volume overload can stretch the tricuspid annulus and cause it to leak, which in turn enlarges the ventricle. However, if these patients are aggressively treated with diuretics, the right ventricle can shrink and regurgitation goes away, he noted.

“I could take a totally useless device, stick it in the tricuspid valve, and then spend a week with the patient fine-tuning [medication] and have a spectacular result,” said Thompson. “But it might not have anything to do with the [device].”

Patients in the study said they felt better after the percutaneous repair, he acknowledged, but more rigor will be needed to move the technology forward. While reduced diuretic usage and an improvement in the 6-minute-walk test would be helpful, Thompson thinks a sham-controlled procedure as part of a randomized trial would be ideal.

At present, there are a few devices being tested for transcatheter tricuspid repair of tricuspid regurgitation, including the Mitralign (Tewksbury, MA) and TriCinch (4Tech Cardio, Dublin, Ireland) systems.

Other Devices in Play

In an editorial, Alec Vahanian, MD, and Jean Michel Juliard, MD, of Bichat Hospital (Paris, France), say the data suggest that transcatheter tricuspid valve repair is feasible and provides good short-term safety with clinical improvement despite the incomplete resolution of regurgitation. Durability and the effect of treatment on right-ventricular function remains to be seen, however.

As for the relatively modest improvement in the degree of tricuspid regurgitation, they point out the system does not reproduce the annuloplasty ring, which has been shown to be superior to stiches and other procedures. Second, the patients in this study had irreversible enlargement of the tricuspid annulus and severe valve tethering. In these type of patients, a surgical replacement would be preferable as the repair would not be expected to provide an effective or durable reduction of tricuspid regurgitation.

As for what happens next, the editorialists say the field of transcatheter tricuspid valve repair should follow the lead of transcatheter aortic valve replacement and carefully evaluate the results and refine the technology.

Sources:
1. Campelo-Parada F, Perlman G, Philippon F, et al. First-in-man experience of a novel transcatheter repair system for treating severe tricuspid regurgitation. J Am Coll Cardiol. 2015;66:2475-2483.
2. Vahanian A, Juliard JM. When transcatheter therapy moves to the “forgotten valve” [editorial]. J Am Coll Cardiol. 2015;66:2484-2486.

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