Page 58 - Read Online

Scotti et al. Vessel Plus 2021;5:6 I http://dx.doi.org/10.20517/2574-1209.2020.68 Page 5 of 10

High morbidity/mortality and suboptimal results undermine the surgical treatment (both repair and
replacement) of SMR. The surgical approach is clearly indicated in the limited setting of patients with LV
ejection fraction (LVEF) > 30% and needing concomitant coronary revascularization through coronary
[9]
artery bypass grafting (class of recommendation = I for LVEF > 30%, IIa for LVEF ≤ 30%) [Figure 3] .
Therefore, transcatheter therapies are widely used for SMR (technical success 97% and 95.8%, stroke 0.7%
and 1.4%, unplanned mitral valve surgery 1% and 0%, and 30-day mortality 2.3% and 3.3%, in COAPT and
MITRA-FR trials, respectively [10,11] ).

Edge-to-edge clips, annuloplasty devices, and TMVRpl valves can be used to treat patients with SMR after
[12]
careful multi-disciplinary assessment . The contrasting yet complementary results of the two available
randomized trials on MitraClip implantation (COAPT and MITRA-FR) [10,11] make it clear that careful
evaluation of clinical and anatomical factors are of primary importance. The response to transcatheter
techniques is expected to be less beneficial in the case of severe LV dilatation, long-standing pulmonary
[13]
hypertension, concomitant atrial fibrillation, and severe chronic kidney disease .

Optimal timing is crucial to obtain the best results in terms of survival and symptomatic benefit. However,
a recent international registry has proved that TMVR may extend its therapeutic window even to patients
[14]
affected by advanced heart failure . This end-stage population can benefit the most from hemodynamic
stabilization, symptomatic relief, and recovery from pulmonary hypertension. These factors can lead these
patients to receiving elective heart transplantation in a good clinical status or even being delisted, no longer
needing this advanced therapy.

ANATOMICAL AND TECHNICAL FEATURES
Transcatheter mitral valve repair
Criteria defining the optimal candidates for TMVR were initially derived from the EVEREST studies ,
[15]
and subsequently validated and expanded from trials and large real-world registries [Figure 3]. From an
anatomical point of view, a flail width ≤ 15 mm, a flail gap < 10 mm, and a single diseased segment are
ideal for successful MitraClip placement in PMR. On the contrary, severely and diffusely thickened (5 mm
in diastole) and retracted (rheumatic disease) or redundant leaflets (Barlow’s type valve) contraindicate
TMVR for PMR. The most important factors to be evaluated for SMR treatment are a sufficient leaflet
tissue (grasping length > 10 mm), a coaptation length ≥ 2 mm, and a coaptation depth ≤ 11 mm. Leaflets
containing perforations, calcifications on the grasping zone, or deep cleft-like indentations are less likely to
return good results. Multivariate logistic regression identified preprocedural mitral valve area ≤ 3 cm and
2
[16]
mean mitral valve gradient > 4 mmHg as independent predictors of overall procedural failure .
Severe annular dilation should guide toward a direct or indirect annuloplasty device as first choice or
complementary tool. In this case, an angio-CT scan should evaluate the proper size of the mitral valve
annulus, the presence of calcifications, and the relations with the circumflex artery.

Transcatheter mitral valve replacement
The complexity of mitral anatomy with its D-shape and well-represented subvalvular apparatus makes
TMVRpl much more challenging than its counterpart on aortic valve position.

A meticulous angio-CT study is mandatory in the screening phase and should evaluate:

(1) the functional anatomy of the left ventricular outflow tract (LVOT) with the presence of a mitral aortic
angle > 120° and the absence of severe septal hypertrophy to avoid a neo-LVOT obstruction, the most
dreaded complication;