Clinical Implications
Cardiac surgeons rely on different annular dimensions measured in the
operating room to choose the correct size of annular ring for mitral
valvuloplasty (21, 23-28). Sizing is of great importance in FMR and DMR
cases in order to avoid residual MR and complications such as iatrogenic
MS and systolic anterior motion of the anterior leaflet (SAM). The vast
majority of surgeons use the Carpentier sizers to choose the correct
annulus ring. These sizers measure the inter-trigonal distance, the
commissural diameter, the anterior leaflet length and the annulus
circumference. Using the dedicated AutoMVQ software with TTE and TOE,
these variables can be measured accurately and help the surgeons to
decide about the ring size in advance. In FMR patients, further
information about the tenting height and area may guide the decision
towards valve repair or replacement, as a very tethered valve appears to
be less successfully reparable, with high rates of MR relapse (25, 29).
A more detailed analysis of the mitral annulus can also guide
transcatheter therapies for valve repair or replacement (21,23).
Transcatheter MV annuloplasty methods require meticulous measurements of
the annulus circumference and currently cardiac computed tomography
(CCT) is the gold standard technique for this measurement (30). However,
previous studies have shown that 3D TOE correlates well with CCT
measurements (16). The MV annulus area and circumference can also guide
the transcatheter MV replacement either with valve-in-MAC (Mitral
Annular Calcification) technique or transcatheter valves dedicated for
the mitral position (intrepid, Tendyne, etc.). (31) All these therapies
use CCT for pre-procedural planning and sizing of the device. 3D
echocardiography though becomes inevitable in patients with renal
failure who cannot undergo a CT scan with iodine contrast due to acute
kidney injury risk. As 3D TOE and CCT correlate well for mitral annular
measurements, 3D TTE can be the first-line diagnostic method for this
subgroup of patients. Moreover, as 3D echocardiography, has the
advantage of avoiding contrast agent and radiation exposure, the need
for further investigation of MVQ analysis and establishment of the
method is warranted.
Finally, another noteworthy feature of this software is the aorto-mitral
angle assessment (27,28). As already known, patients referred for MV
replacement (surgical or transcatheter) are not suitable for that
surgery if abovementioned angle is too narrow due to high probability of
creating a small neo-LVOT with high gradients. The aorto-mitral angle
may also increase the risk of creating SAM in MV repair cases where an
annular ring is placed.
Till recently, all these data were depicted from analysis of TOE images.
However, there is a subgroup of patients that have relative or absolute
contraindications for TOE (5-10) or cannot tolerate the adult TOE probe
even under sedation. As shown in our study, all necessary information
for mitral annulus and leaflets can be provided with analysis of 3D TTE
images with the AutoMVQ software with high accuracy and good correlation
with TOE and CCT measurements.