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A novel system for valve leaflet coaptation may yield clinical improvements, though only modestly reducing tricuspid regurgitation jets, according to the first-in-human experience.

Fifteen patients successfully got transcatheter tricuspid valve repair with the Forma system from Edwards Lifesciences, all except one of whom had 1-year follow-up. Outcomes improved by 1 year:

• 79% were in New York Heart Association (NYHA) class I/II, whereas 94% started in class III at baseline (P<0.001)
• The average 6-minute walk test went up by 84 meters (P=0.03)
• Kansas City Cardiomyopathy Questionnaire scores for heart failure saw an 18-point boost (P=0.02)

On echocardiography, however, tricuspid regurgitation was just reduced for the majority from severe at baseline to moderate-severe at 30 days (P=0.001). Half of patients , John Webb, MD, of St. Paul's Hospital in Vancouver, Canada, and colleagues reported online in JACC: Cardiovascular Interventions.

"At 1 year, despite variable success in reducing echocardiographic tricuspid regurgitation grade, there were significant clinical improvements and reductions in right ventricular dimensions," they said, citing the shrinking of the tricuspid annulus from 45.7 to 42.1 mm in diameter (P=0.004) and the right ventricle from 54 to 59.9 mm in diameter (P=0.02).

"The FORMA device, distinct from other transcatheter tricuspid valve technologies involving direct annuloplasty or leaflet plication, uses a transcatheter rail anchored in the interventricular groove of the right ventricle to deliver a spacer occupying the center of the dilated tricuspid valve annulus, allowing for leaflet coaptation onto the surface of the spacer, in order to reduce tricuspid regurgitation," commented Mackram Eleid, MD, of the Mayo Clinic in Rochester, Minn.

In an accompanying editorial, Eleid called the Forma procedure "simple" but prone to injuring or dislodging from the thin-walled right ventricle.

Webb's group had 89% procedural success. Failures were attributed to right ventricular perforation or device dislocation into the right atrium, with the latter happening within hours of the intervention due to poor anchoring.

"Improvements in patient selection, procedural techniques, and iterative improvements in delivery catheter steerability hold the potential to lower risk of these complications, and/or allow application to patients with more challenging right ventricular anatomy due to extreme angulation, prominent trabeculations, or unfavorable pre-existing pacemaker/defibrillator lead location," the editorial suggested.

The Forma system was tested in 18 high-risk patients with severe tricuspid regurgitation who got it under compassionate use. Two centers in Canada and one in Switzerland placed the Forma -- available in 12- and 15-mm diameter sizes -- under general anesthesia with transesophageal echocardiography.

Most patients improved by at least one NYHA functional class (86%).

No procedural deaths, MIs, or pulmonary embolisms occurred. At 1 year, there were no deaths, pulmonary embolisms, device-related infections, or severe arrhythmias requiring intervention. One patient had a transient ischemic attack; another had device thrombosis at 4 months that resolved after 2 months of anticoagulation.

"Current guidelines recommend oral anticoagulation for 3 months following tricuspid valve bioprosthetic valve implantation. It is however unclear at this stage if there is need for anticoagulation after Forma system implantation and for how long this might be needed in patients who do not have other indications for anticoagulation," according to Webb and colleagues.

"The addition of a larger spacer device (18 mm) is expected to improve tricuspid regurgitation reduction in patients with larger effective regurgitant orifice areas, which seem to represent a large proportion of the population considered for transcatheter repair," Eleid suggested.

In the meantime, the question remains of how to measure tricuspid regurgitation, given that Forma implantation prevents good color Doppler assessment, he added.