Page 34 - Read Online

Echarte-Morales et al. Vessel Plus 2021;5:54 https://dx.doi.org/10.20517/2574-1209.2020.105 Page 5 of 13

Percutaneous mitral valve repair
MitraClip (Abbott, Santa Clara, CA, USA) is a polyester-coated chromium-cobalt device that is advanced
via the femoral vein into the left atrium through a transseptal puncture under transesophageal
[25]
echocardiographic (TEE) guidance . Based on the Alfieri surgical technique, the clip grasps the edge of the
anterior and posterior leaflets within the central part of the MV at the point where the regurgitant jet
originates. If needed, more than one clip can be deployed to further reduce MR in the absence of
significantly increased MV gradient. The safety and efficacy of the procedure has been demonstrated in
[25]
several trials and registries in patients with native MV diseases . In this regard, PMVR currently represents
the standard of care for patients with SMR and a less invasive alternative for patients with PMR at high risk
[4]
for conventional surgery .

PMVR can also be an alternative for patients who develop significant MR after MVr [Figure 1]. The first
experience in this setting was reported by Lim et al. in 2010. In this study, two patients with SMR who
[26]
had previously received CABG and MV annuloplasty underwent successful PMVR showing persistent
reduction in MR and clinical and hemodynamic improvement in mid-term follow-up. More recently,
different case series have reported reasonable results with low morbimortality [Table 3] [27-31] . In the largest to
date reported series, Braun et al. included 57 patients (76 ± 9 years, STS score 6 ± 5, 52% SMR) undergoing
[29]
PMVR after MVr (79% with annuloplasty ring). The etiology of recurrence in the cases of PMR was
recurrent prolapse or flail (50%), leaflet tethering (27%), or partial ring dehiscence (23%), whereas, in
patients treated for SMR, leaflet tethering was the most common underlying mechanism (53%). Patients
2
included in this registry met the following anatomical criteria: mitral valve area ≥ 2.5 cm , visible mobile
length of mitral leaflets ≥ 5 mm, flail height ≤ 10 mm, flail width ≤ 15 mm, and five central or adjacent jet
origins.

In this selected cohort, acute procedural success (residual MR ≤ 2+) was achieved in 84% of patients and did
not significantly differ according to the etiology of native MV disease or the technique used for MVr.
Significant, although modest, increase in transmitral gradient (3.1 ± 1.4 to 4.3 ± 1.5 mmHg) and decrease in
MV area (3.5 ± 1.2 to 2.4 ± 1.0 cm ) were observed after PMVR, with no MAE within in-hospital stay.
2
During a mean follow-up of 15.9 ± 15.5 months in 47 patients, six subjects died, 82% had residual MR ≤ 2+,
and 66% were in NYHA functional Class I or II.

From a technical perspective, some difficulties may be found during PMVR in patients with prior surgical
annuloplasty, which is by far the most common MVr approach nowadays. First, the most common issue is
probably that the quality of TEE imaging for procedural guidance is impaired. In some cases, shadowing
from the annuloplasty ring may create dropout artifacts and obscure the edge of both leaflets, thus
challenging the grasping of the clip. Therefore, additional imaging such as transthoracic or intracardiac
echocardiography (ICE) might be needed to achieve successful procedural outcomes. In this regard,
[32]
Saji et al. reported their experience of PMVR in five patients with failed prior surgical rings using 2D ICE
as an adjunctive imaging guidance given suboptimal TEE imaging alone. They introduced a 9F sheath via
the femoral artery and placed the ICE catheter in the LV through this sheath, which was rotated afterwards
to create a short axis of the MV. The acute procedural success rate was 80% and no complications related to
ICE were documented. The authors concluded that the quality of imaging was good enough to help the
procedure and this approach might reduce procedural time in selected cases. Second, the surgical ring might
entangle with the clip arms or grippers, requiring meticulous maneuvers under 3D TEE guidance . Third,
[33]
pre-existing annuloplasty ring and/or thickening of neochords might significantly increase the transmitral
gradient after clipping, leading to procedural failure . In this regard, left atrial hemodynamics and 3D TEE
[28]
[33]
planimetry of the residual MV area may help to determine if that result can be acceptable . Fourth, in