Echocardiography:
Each patient underwent 2D-transthoracic echocardiogram (TTE) before TMVI, 2D-TTE pre-discharge and further TTEs at 1 and 3-months. Patients were excluded if TTE data were not available or acquired outside the study time period. TTE images were obtained using an EPIQ 7 (Phillips Healthcare, Eindhoven, the Netherlands) or Vivid 95 (GE Medical Systems, Horten, Norway) ultrasound machine. Standardized measurements were performed at the time of image acquisition or offline using local hospital reporting systems in accordance with guidelines from the American Society of Echocardiography [14]. Measurements using 2D-speckle tracing echocardiography (STE) were performed offline using EchoInsight Pro (Epsilon Imaging, Michigan, USA) with a frame rate of at least 30 frames/s (Figure 1).
Patients were stratified into two groups based on the pre-operative LV ejection fraction (EF). LV function was quantified by recording LVEF using the Simpson’s biplane method, LV end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), end-diastolic volume (LVEDV), end-systolic volume (LVESV), LV global longitudinal strain (GLS), circumferential and radial strain (Figure 2). Global RV systolic function was recorded qualitatively as a categorical variable (mild, moderate or severe) and quantitatively by: pulmonary artery systolic pressure (PASP), RV fractional area change (RVFAC), RV longitudinal myocardial velocity (RVS’), RV basal diameter, RV free wall longitudinal strain (FWLS) and tricuspid annular plane systolic excursion (TAPSE). RVFWLS was calculated as the systolic peak of the average curve from a 6-segment ROI after manually excluding the septal segments [15, 16] and defined as normal if < -20% [14, 17, 18].
Degree of valvular regurgitation of the mitral and tricuspid valves were recorded qualitatively as categorical variables (mild, moderate, moderate-severe, severe), and in the case of MR, quantitatively by: proximal isovelocity surface area (PISA), regurgitation fraction (RF), end regurgitant orifice area (EROA), regurgitant volume and vena contracta (VC).
All 2D-STE measurements were analyzed offline by two experienced independent observers (SH & NB). For assessment of intra- and inter-observer variability, each observer was blinded to the other observer’s results. Measurements were repeated after a >4-week interval by the same observers blinded to the initial measurements and reproducibility was comparable with quaternary centers experienced in the technique (Table 1). 2D-TTE image quality was sufficient to perform volumetric analysis in all 46 patients, but on 41 occasions (41/138; 30% of all TTEs analyzed), the image quality was insufficient or not available to perform full 2D-STE analysis.