**3. Transcatheter therapies for tricuspid regurgitation**

Given the unmet need for invasive correction of TR with an assumable procedural risk, different percutaneous devices have been developed in recent years based on previous surgical techniques and percutaneous devices dedicated for the treatment of left-side valve disease. **Table 3** summarizes anatomical target and surgical background, if any, of current available devices for transcatheter treatment of TR, including percutaneous TV repair (PTVR) techniques and orthotopic and heterotopic transcatheter TV valve implantation (TTVI). To date, only 3 devices have already obtain the CE mark for clinical practice [12, 31].

#### **3.1 Percutaneous tricuspid valve repair**

#### *3.1.1 Percutaneous coaptation devices*

These devices are designed to ultimately minimize the coaptation gap, including: 1) MITRACLIP in the tricuspid position or TRICLIP that approximate the leaflets

*Percutaneous Treatment of Tricuspid Regurgitation DOI: http://dx.doi.org/10.5772/intechopen.95799*


#### **Table 3.**

*Transcatheter therapies for tricuspid regurgitation.*

increasing its coaptation surface; 2) FORMA device, comprising a spacer that occupies the regurgitant orifice; 3) PASCAL, that combines clipping of leaflets with a minor spacer; and 4) the MISTRAL device that approaches leaflets' coaptation edge by stretching the subvalvular apparatus (**Figure 1**).

#### a.MITRACLIP/TRICLIP

MitraClip (Abbott Vascular, Santa Clara, CA, USA) is a polyester-coated chromium-cobalt device with two arms that open and close in a controlled manner through the release system. The device can be repositioned and more devices can be implanted until an adequate reduction of the valve insufficiency is achieved. This device was initially designed for the percutaneous treatment of mitral regurgitation and has already been used in over 100.000 for this purpose. With this back up of experience gained in the treatment of mitral regurgitation, it began to be used as an off-label therapy for TR and become the most widely used PTVR device (70% of all procedures).

The TriValve registry evaluated the results of MitraClip at 1-year follow-up in a series of 249 patients with TR [32]. Concomitant treatment of the mitral valve was carried out in 52% of the cases and two or more clips were implanted in 69.1% of the patients received, most of them (65%) at the anteroseptal commissure (65%). Procedural success, defined as TR reduction to grade ≤ 2+, was achieved in 77% of cases and an improvement in functional class to NYHA ≤ II

**Figure 1.** *Tricuspid coaptation devices. A: TRICLIP, B: PASCAL, C: FORMA, D: MISTRAL.*

was observed in 69% of patients. The following factors were identified as independent predictors for procedural failure: tenting area > 3.15 cm2 , non-central jet, regurgitation through the anteroposterior or posteroseptal commissure, coaptation gap >6.5 mm and regurgitant area > 0.695 cm2 .

From a technical point of view, two approaches have been described for reducing TR with MitraClip: the triple-orifice technique in which the clips are positioned centrally between the septal and the anterior leaflets, as well as between the septal and the posterior leaflets; and the bicuspidization procedure in which clips are deployed between the anterior and the septal leaflets [33] (**Figure 2**). Clipping of the anteroposterior commissure can be challenging and, sometimes, this may distort the valve and worsen TR [34].

The TriClip (Abbott Vascular, Santa Clara, CA, USA) is a dedicated MitraClip device for the TV. The prospective single-arm multicenter TRILUMINATE study evaluated the safety and feasibility of this system for treating TR. The 6-month results involving 85 patients have recently been published [35]. Patients with severe PH or relevant mitral valve insufficiency were excluded. Technical success was achieved in all the patients and most clips were deployed between the anterior and septal leaflets (77%) with a reduction of at least one grade in the severity of TR in 91% of the cases. At 6-month follow-up, 86% of the patients presented moderate or less TR and were in NYHA functional class was I-II, and a significant improvement in the 6-minute walking test was observed.

*Percutaneous Treatment of Tricuspid Regurgitation DOI: http://dx.doi.org/10.5772/intechopen.95799*

#### **Figure 2.**

*A: Percutaneous tricuspid valve repair with MitraClip. B: Triple-orifice technique. C: Bicuspidization aproach.*

Patients with significant TR and implantable cardiac devices represent a particularly challenging population. In a cohort of the TriValve registry, PTVR was performed in 121 patients with an intracardiac RV electrodes. Most of these patients, 106 (87%), were treated with MitraClip and compare to those without intracardiac devices, no significant differences were documented in procedural success, TR reduction (TR ≤ 2+ 73.7% vs. 70.8%, p = 0.6), clinical improvement or survival [36].

#### b.PASCAL

The Pascal system combines the possibility of grasping the leaflets as with the MitraClip device with the use of a spacer. This affords improved coaptation and better outcomes following percutaneous repair of TR. The first experience targeted to the tricuspid valve in humans have recently been published [37]. Out of 28 patients (98% with functional TR), the procedure success rate was 86%, with no complications in any case. Forty devices were implanted - mostly in the anteroseptal position (70%). Detachment of the device was recorded in two patients, and 85% of the subjects presented TR ≤ 2+ after 30 days.

Although no clinical trials have compared any of these therapies versus placebo in patients with TR, an observational study has compared the use of the MitraClip with the PASCAL system in the treatment of this valve disease. In

this study published by Braun et al., in which 88 patients were treated with the MitraClip and 32 received the PASCAL system, no differences were observed between the two devices in terms of success of the procedure, the reduction of TR or detachment of the device (11% with MitraClip versus 6% with PAS-CAL). The authors concluded that both devices are similar in terms of efficacy and safety in reducing TR [38].

## c.FORMA

The FORMA system (Edwards Lifesciences, Irvine, CA, USA) is designed to increase leaflet coaptation, occupying the regurgitant orifice with a spacer [39]. A guide is advanced through the subclavian or axillary vein and anchored in the apex of the right ventricle. The spacer is then advanced to the tricuspid valve plane. Finally, the excess guide is implanted in a subcutaneous pouch. The results after 2–3 years of the first cohort of 19 patients treated with this system have recently been published [40]. The procedure proved successful in 89% of the patients, with the recording of one case of right ventricle perforation. After four months another patient suffered thrombosis of the device, and pulmonary thromboembolism was also evidenced in another subject. Although functional class improvement was observed in 93% of the cases, at last followup only one-third of the patients presented moderate or lesser TR. The FORMA early feasibility study reported two right ventricle perforations in the cohort of 29 patients. A decrease in TR was seen in 49% of the cases [40]. Despite these outcomes, most of the patients experienced improvement of their functional class. The single-arm SPACER trial is currently ongoing and will evaluate mortality after 30 days with this device.
