Background:
The most frequently used system for a transcatheter tricuspid valve repair (TTVr) in the treatment of severe tricuspid regurgitation (TR) is the edge-to-edge technic. A specific TriClip delivery system for the tricuspid valve was introduced and received CE-mark in 04/2020, and thus was available in our institution since 11/2020. This system has a steerable guiding catheter that specifically adapts to the right side of the heart, and has two clip sizes available to enhance successful Clip delivery to the tricuspid valve. 

Aim:
(1) To assess the feasibility, safety, and effectiveness of TriClip delivery system for TTVr, and (2) to compare the novel system with the previously used MitraClip system.

Methods:
All patients treated with TTVr at our institution are prospectively included in our Clip-registry, where clinical, laboratory, echocardiographic and invasive parameters were obtained. After the introduction of the TriClip system, we solely implanted TriClip XT devices. Thus, 14 patients previously treated with the equivalent Mitra Clip XT were compared to 11 patients treated with the novel TriClip XT system. The primary outcome was successful TTVr using one or more XT-Clips with TR reduction of ≥ 1 grade with no mortality, single leaflet device attachment (SLDA), or conversion to surgery until hospital discharge. At 30-day follow-up, reduction in TR severity grade and improvement of NYHA functional class were assessed.

Results:
There was no difference between the baseline patients characteristics, echocardiographic parameters or initial NYHA functional class (2.9±0.6 in TriClip XT vs 3.2±0.4 in MitraClip XT group, p=0,24). Initial TR grade was 4.3 ±0.7 in MitraClip XT and 4.2 ±0.9 in TriClip XT group (p=0.74).

No significant differences were observed in intervention duration, fluoroscopy time or dose area product. In all patients (100%) using TriClip delivery system, clip implantation was successful and without complications, whereas the TTVr procedure failed in two patients treated with MitraClip XT (successful implantation rate: 100 % vs. 85.7%; p=0.21). Furthermore, three patients (21%) in MitraClip XT group had an SLDA before discharge, so that just 9 patients (64.3%) achieved the primary outcome compared to all 11 patients (100%) in the TriClip XT group (p=0.03). TR grade at discharge was significantly reduced in both groups (2.2±0.9 in TriClip XT and 2.8±1.2 in MitraClip XT group, p<0.001) without significant difference between groups (p=0.25).

At 30-day follow-up, we observed a total of SLDA resulting in severe TR in one patient (9%) in TriClip XT, and in three patients in the MitraClip XT group (21 %, p = 0.45).  Overall success rate was with 88.9% vs. 50 % (p = 0.04) significantly higher in the TriClip XT group due to two more patients presenting with worsening TR grade at f/u in the MitraClip XT group on top of the observed SLDA cases. TR grade at 30-day follow-up was significantly reduced with a greater mean reduction in TriClip XT group (2.4±0.54 vs 3.1±0.8, p=0.03). Overall, improvement of NYHA functional class at f/u compared to baseline was observed in both groups.

Conclusion:
TTVr of severe TR in a fragile population is a complex procedure requiring an experienced operator and team. Adequate patient selection and use of refined devices with an enhanced delivery system seem to be key components for a successful intervention.