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Transcatheter valve repair for severe symptomatic tricuspid regurgitation has been somewhat unsuccessful, according to current real-world experience, but operators blamed this on a conventional definition of success that may be more suited for other valve procedures.

Using an array of devices -- most commonly the MitraClip -- operators achieved 62% procedural success (defined as the patient being alive at the end of the procedure, with the device successfully implanted, delivery system retrieved, and a residual jet grade 2 or below), according to a study online in .

Yet this "seemingly suboptimal" figure, according to the TriValve Registry collaborators, led by Maurizio Taramasso, MD, of the University Hospital of Zurich, Switzerland, failed to reflect that 59% of the high-risk patients had settled into New York Heart Association functional class I or II 30 days after valve repair (up from 4% at baseline, P=0.003).

"The main results are that transcatheter tricuspid valve intervention is feasible with different devices, with a high safety profile and, despite suboptimal anatomic results in some cases, it is associated with promising short-term clinical benefits," the researchers concluded.

Transcatheter therapies had a fairly good safety profile, with 30-day all-cause mortality at 3.7% and major adverse cardiac and cerebrovascular events reaching 22.2% (mostly rehospitalization for heart failure). Tricuspid intervention stood alone as an isolated procedure in 68% of cases, with the rest performed concomitantly with a transcatheter mitral procedure.

Tricuspid regurgitation jets of grades 3 and 4 were present in one-third and two-thirds of the population, respectively, on baseline. By procedure's end, jets were somewhat better: grade 4 in 22%, grade 3 in 29%, grade 2 in 34%, and grade 1 in 15%.

"Given the discordance between tricuspid regurgitation reduction and clinical improvement, it is evident that we cannot use definitions of procedural success for the tricuspid valve that have been used for the aortic and mitral valves," the investigators emphasized.

In an , however, one clinician was more cautious about the existence of such a discord: "Although there was improvement in New York Heart Association functional class at 30-day follow-up, this registry did not include quality-of-life questionnaires or functional metrics such as the 6-minute walk test, so it is difficult to gauge exactly how much better patients felt," wrote Jason H. Rogers, MD, director of Interventional Cardiology and medical director of the Cardiovascular Research Unit of the University of California Davis Medical Center in Sacramento.

Rogers did concede that conventional endpoints such as jet reduction or ventricular remodeling "may not be sufficient to capture the clinical impact of early transcatheter devices, and development of novel endpoints specific to these patients will be essential (such as diuretic dosage, the amount of ascites, liver function, calf circumference, and body weight)."

Moreover, Taramasso's group suggested that current guideline definitions don't do severe tricuspid regurgitation any justice; the 1.1-cm average vena contracta and 63-ml regurgitant volume in this series far exceed current criteria for "severe" regurgitation: "It seems clear that given the extreme severity of regurgitation in many patients, the current grading schemes are inadequate to the wide spectrum of severe tricuspid regurgitation and need to be redefined," the researchers said.

Eleven cardiac centers in Europe and North America contributed data to the TriValve Registry starting in November 2016. The dataset included 106 high-risk patients (mean age of 76; 60.4% women) not included in other trials.

Participants went into the procedure with tricuspid regurgitation of functional etiology in 95.2% of cases; the jet was mainly central 76.9% of the time. Patients had a mean tricuspid annulus of 45.4 mm; systolic pulmonary artery pressure was 39.7 mm Hg; and the inferior vena cava was severely dilated, to 27.4 mm.

Additionally, right ventricular dysfunction was present in 56.3% of participants, and 35% had prior left heart intervention.

Transcatheter tricuspid valve therapy consisted of: MitraClip (n=58), Trialign (n=17), TriCinch (n=15), FORMA (n=7), Cardioband (n=5), or caval valve implantation (n=3). One case had combined Trialign and MitraClip.

Patients shared a similar risk profile and degree of right ventricle dysfunction across therapy groups.

In terms of study limitations, the TriValve Registry had no control group, and there was also no core-lab adjudication, the researchers noted. In addition, since the registry was relatively new, no long-term data were available. Given these limitations, it remains unknown which patients are the best candidates for transcatheter tricuspid repair, which approaches are best, and when, the team acknowledged.

"It is also provocative to note that none of the devices presented in this registry faithfully mimic the current surgical standards for tricuspid regurgitation correction, which consist primarily of rigid ring annuloplasty, or tricuspid valve replacement," Rogers said. "Other technologies in development or new techniques will undoubtedly come forward in the future to address this mechanistic gap.

"Ultimately, the goal of reducing tricuspid regurgitation to mild or trace was not consistently achieved in this registry, and innovators should continue to strive for this goal."