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.