Standardization and validation of neoLVOT assessment using three-dimensional trans-esophageal echocardiography before trans-catheter mitral valve replacement.

BACKGROUND: Trans-catheter mitral valve replacement (TMVR) procedures had emerged as an alternative solution for patients who are at high risk for mitral valve surgery. Although cardiac computed tomography (CT) remains the standard method for procedural planning, there is no full agreement on the best systolic phase for quantitation of the neoLVOT. Furthermore, a new three-dimensional trans-esophageal echocardiography (3DTEE) based software was developed to serve as filter and or an alternative for patients who cannot have CT due to any contraindication. AIM: To determine the systolic phase of the cardiac cycle that shows the narrowest NeoLVOT area in order to standardize the way of using these software and then to validate the 3DTEE-based software against the CT-based one as a gold standard, in mitral valve annulus (MA) and NeoLVOT assessment. METHODS: A single center, observational, retrospective study. Initially, a sample of 20 patients (age 62 ± 4 years, 70% men) had CT-based analysis at mid-diastole (80%), early-systole (10%), mid-systole (20%), late-systole (30%-40%), in order to detect the best systolic phase at which the neoLVOT area is the narrowest after TMVR. Then, the end systolic phase was standardized for the analysis of 49 patients (age 57 ± 6 years, 60% men), using both the commercially available CT-based software and the newly available 3DTEE-based software (3mensio Structural Heart, Pie Medical Imaging, The Netherlands). The 3DTEE derived parameters were compared with the gold standard CT-based measurements. RESULTS: The neoLVOT area was significantly narrower at end-systole (224 ± 62 mm2), compared to early-systole (299 ± 70 mm2) and mid-systole (261 ± 75 mm2), (p = .005). Excellent correlation was found between 3DTEE and CT measurements for MA AP diameter (r = .96), IC diameter (r = .92), MA area (r = .96), MA perimeter (r = .94) and NeoLVOT area (r = .96), (all p-values < .0001). Virtual valve sizing was based on annulus measurement and was identical between CT and 3DTEE. Interobserver and intraobserver agreements were excellent for all the measurements with ICCs > .80. CONCLUSIONS: End-systole is the phase that shows the narrowest neoLVOT and hence should be the standard phase used during the analysis. The 3DTEE based analysis using this new software is reliable compared to the CT-based analysis and can be serve as an alternative analysis tool in patients who cannot have CT for any clinical contraindication or as a screening test and/or filter for all patients before proceeding to a detailed CT scan.

Feasibility and reliability of comprehensive three-dimensional transoesophageal echocardiography screening process for transcatheter mitral valve replacement.

AIMS: The procedural planning of transcatheter mitral valve replacement (TMVR) requires a specific imaging assessment to establish patient eligibility. Computed tomography (CT) is considered the reference method. In this setting, data regarding the role of transoesophageal echocardiography (TOE) are lacking. We evaluated the feasibility and reliability of a comprehensive 3D-TOE screening in TMVR candidates. METHODS AND RESULTS: We performed a retrospective observational study including 72 consecutive patients who underwent a pre-procedural CT and 3D-TOE for TMVR evaluation. The measurements of mitral annulus (MA), length of anterior mitral leaflet (AML), native left ventricular outflow tract (LVOT), and predicted neo-LVOT acquired with CT and 3D-TOE were compared using a novel semi-automated software for post processing analysis (3 mensio Structural Heart 10.1-3mSH, Pie Medical Imaging, Bilthoven, Netherlands). The final suitability decision was given by the valve manufacturer based on CT measurements and clinical conditions. Among 72 patients screened, all patients had adequate image quality for 3D-TOE analysis. 3D-TOE and CT measurements for AML length (r = 0.97), MA area (r = 0.90), perimeter (r = 0.68), anteroposterior (r = 0.88), and posteromedial-anterolateral (r = 0.74) diameters were found highly correlated, as well as for native LVOT (r = 0.86) and predicted neo-LVOT areas (r = 0.96) (all P-values <0.0001). An almost perfect agreement between CT and 3DTOE was found in assessing the eligibility for TMVR implantation (Cohen kappa 0.83, P < 0.001). CONCLUSION: 3D-TOE appraisements showed good correlations with CT measurements and high accuracy to predict TMVR screening success.

Assessing the Hemodynamic Impact of Anterior Leaflet Laceration in Transcatheter Mitral Valve Replacement: An in silico Study.

Background: A clinical study comparing the hemodynamic outcomes of transcatheter mitral valve replacement (TMVR) with vs. without Laceration of the Anterior Mitral leaflet to Prevent Outflow Obstruction (LAMPOON) has never been designed nor conducted. Aims: To quantify the hemodynamic impact of LAMPOON in TMVR using patient-specific computational (in silico) models. Materials: Eight subjects from the LAMPOON investigational device exemption trial were included who had acceptable computed tomography (CT) data for analysis. All subjects were anticipated to be at prohibitive risk of left ventricular outflow tract (LVOT) obstruction from TMVR, and underwent successful LAMPOON immediately followed by TMVR. Using post-procedure CT scans, two 3D anatomical models were created for each subject: (1) TMVR with LAMPOON (performed procedure), and (2) TMVR without LAMPOON (virtual control). A validated computational fluid dynamics (CFD) paradigm was then used to simulate the hemodynamic outcomes for each condition. Results: LAMPOON exposed on average 2 ± 0.6 transcatheter valve cells (70 ± 20 mm2 total increase in outflow area) which provided an additional pathway for flow into the LVOT. As compared to TMVR without LAMPOON, TMVR with LAMPOON resulted in lower peak LVOT velocity, lower peak LVOT gradient, and higher peak LVOT effective orifice area by 0.4 ± 0.3 m/s (14 ± 7% improvement, p = 0.006), 7.6 ± 10.9 mmHg (31 ± 17% improvement, p = 0.01), and 0.2 ± 0.1 cm2 (17 ± 9% improvement, p = 0.002), respectively. Conclusion: This was the first study to permit a quantitative, patient-specific comparison of LVOT hemodynamics following TMVR with and without LAMPOON. The LAMPOON procedure achieved a critical increment in outflow area which was effective for improving LVOT hemodynamics, particularly for subjects with a small neo-left ventricular outflow tract (neo-LVOT).

Dynamic nature of the LVOT following transcatheter mitral valve replacement with LAMPOON: new insights from post-procedure imaging.

AIMS: To characterize the dynamic nature of the left ventricular outflow tract (LVOT) geometry and flow rate in patients following transcatheter mitral valve replacement (TMVR) with anterior leaflet laceration (LAMPOON) and derive insights to help guide future patient selection. METHODS AND RESULTS: Time-resolved LVOT geometry and haemodynamics were analysed with post-procedure computed tomography and echocardiography in subjects (N = 19) from the LAMPOON investigational device exemption trial. A novel post hoc definition for LVOT obstruction was employed to account for systolic flow rate and quality of life improvement [obstruction was defined as LVOT gradient >30 mmHg or LVOT effective orifice area (EOA) ≤1.15 cm2]. The neo-LVOT and skirt neo-LVOT were observed to vary substantially in area throughout systole (64 ± 27% and 25 ± 14% change in area, respectively). The peak systolic flow rate occurred most commonly just prior to mid-systole, while minimum neo-LVOT (and skirt neo-LVOT) area occurred most commonly in early-diastole. Subjects with LVOT obstruction (n = 5) had smaller skirt neo-LVOT values across systole. Optimal thresholds for skirt neo-LVOT area were phase-specific (260, 210, 200, and 180 mm2 for early-systole, peak flow, mid-systole, and end-systole, respectively). CONCLUSION: The LVOT geometry and flow rate exhibit dynamic characteristics following TMVR with LAMPOON. Subjects with LVOT obstruction had smaller skirt neo-LVOT areas across systole. The authors recommend the use of phase-specific threshold values for skirt neo-LVOT area to guide future patient selection for this procedure. LVOT EOA is a 'flow-independent' metric which has the potential to aid in characterizing LVOT obstruction severity.

Accuracy of three-dimensional computational modeling in prediction of the dynamic neo left ventricular outflow tract with transcatheter mitral valve replacement.

BACKGROUND: Transcatheter mitral valve replacement (TMVR) offers a valuable treatment option for inoperable patients suffering from a degenerated mitral valve after previous ring annuloplasty. Dynamic obstruction of the left ventricular outflow tract(LVOT) is a procedural risk with detrimental consequences and can be estimated upfront using a multi-slice computed tomography(MSCT) derived 3D computational model(3DCM). This study explored the accuracy of pre-procedural neo-LVOT prediction in TMVR using 3DCMs of multiple cardiac phases. METHODS: We obtained both pre- and post-procedural MSCT scans of a patient who underwent uncomplicated TMVR and derived 3DCMs from each cardiac phase. Virtual implantations of the deployed valve were performed and neo-LVOT dimensions were semi-automatically calculated in the pre-procedural models and matched with the post-procedural models. Predicted and post-procedural neo-LVOTs were compared between 3DCMs. RESULTS: From cardiac phases 20-70%, 11 matched 3DCM pairs were generated. The mean difference between predicted and post-TMVR neo-LVOT area was 3 ± 23 mm2. The intra-class correlation coefficient for absolute agreement between predicted and post-procedural neo-LVOT area was 0.86 (95%CI 0.56-0.96, p < 0.001). CONCLUSION: 3DCMs could accurately predict post-TMVR neo-LVOT dimensions in a patient with a pre-existing mitral annular ring. Prospective research is warranted to demonstrate the accuracy of these models in larger samples and different mitral annular phenotypes.

A Simplified In Silico Model of Left Ventricular Outflow in Patients After Transcatheter Mitral Valve Replacement with Anterior Leaflet Laceration.

In silico modeling has been proposed as a tool to simulate left ventricular (LV) outflow tract (LVOT) obstruction in patients undergoing transcatheter mitral valve replacement (TMVR). This study validated a simplified approach to simulate LV outflow hemodynamics in the setting of TMVR with anterior leaflet laceration, a clinical technique used to mitigate the risk of LVOT obstruction. Personalized, 3-dimensional computational fluid dynamics models were developed from computed tomography images of six patients who underwent TMVR with anterior leaflet laceration. LV outflow hemodynamics were simulated using the patient-specific anatomy and the peak systolic flow rate as boundary conditions. The peak outflow velocity, a clinically relevant hemodynamic metric, was extracted from each simulation (vsim-peak) and compared with the clinical measurement from Doppler echocardiography (vclin-peak) for validation. In silico models were successfully developed and implemented for all patients. The pre-processing time was 2 h per model and the simulation could be completed within 3 h. In three patients, the lacerated anterior leaflet exposed open cells of the transcatheter valve to flow. Good agreement was obtained between vsim-peak and vclin-peak (r = 0.97, p < 0.01) with average discrepancies of 5 ± 2% and 14 ± 1% for patients with exposed and unexposed cells of the transcatheter valve, respectively. The proposed in silico modeling paradigm therefore simulated LV outflow hemodynamics in a time-efficient manner and demonstrated good agreement with clinical measurements. Future studies should investigate the ability of this paradigm to support clinical applications.

Neo-LVOT and Transcatheter Mitral Valve Replacement: Expert Recommendations.

With the advent of transcatheter mitral valve replacement (TMVR), the concept of the neo-left ventricular outflow tract (LVOT) was introduced and remains an essential component of treatment planning. This paper describes the LVOT anatomy and provides a step-by-step computed tomography methodology to segment and measure the neo-LVOT while discussing the current evidence and outstanding challenges. It also discusses the technical and hemodynamic factors that play a major role in assessing the neo-LVOT. A summary of expert-based recommendations about the overall risk of LVOT obstruction in different scenarios is presented along with the currently available methods to reduce the risk of LVOT obstruction and other post-procedural complications.

Cardiac Computed Tomography (CT) Evaluation of Valvular Heart Disease in Transcatheter Interventions.

PURPOSE OF REVIEW: To establish the actual role of CT in the growing field of transcatheter valve interventions (THV). RECENT FINDINGS: The development of empirical CT measurements, which are linked with outcomes. CT is a reliable technique for assessing risk and planning transcatheter valve interventions for mitral and aortic valves. Pulmonic and tricuspid valve assessment with CT imaging is still in the early stages but there is room for development.

Novel Multiphase Assessment for Predicting Left Ventricular Outflow Tract Obstruction Before Transcatheter Mitral Valve Replacement.

OBJECTIVES: This study proposes a physiologic assessment of left ventricular outflow tract obstruction (LVOTO) that accommodates changes in systolic flow and accounts for the dynamic neo-left ventricular outflow tract (LVOT). BACKGROUND: Patients considered for transcatheter mitral valve replacement trials often screen-fail because of the perceived risk of LVOTO. In the Intrepid Global Pilot Study, assumed risk of LVOTO was based on computed tomography estimates of the neo-LVOT area computed at end-systole. However, this may overestimate actual risk. METHODS: Retrospective analyses were performed for screen-failed patients for potential LVOTO (n = 33) and treated patients (n = 29) with available dynamic computed tomography. A multiphase assessment of the neo-LVOT area was performed and represented as: 1) multiphase average; and 2) early systolic value. Prospective evaluation was performed in 9 patients approved for enrollment with multiphase and early systole methods that would have previously screen-failed with the end-systolic approach. RESULTS: Of 166 patients screened for possible inclusion; 32 were screen-failed for nonanatomical reasons. Screen failure for assumed LVOTO risk occurred in 37 of 134 (27.6%) patients. Retrospective analysis indicated a potential enrollment increase of 11 of 33 (33.3%) and 18 of 33 (54.5%) patients using multiphase and early systolic assessment methods. In the prospective cohort, there were no clinical observations of LVOTO 30 days post-procedure, despite assumed risk based on end-systolic estimates. CONCLUSIONS: Multiphase, and specifically early systolic, assessment of the neo-LVOT may better determine risk of LVOTO with transcatheter mitral valve replacement compared with end-systolic estimates. This novel approach has the potential to significantly increase patient eligibility, with over one-half of patients previously screen-failed now eligible for treatment.

Prevention and Treatment of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement.

Transcatheter mitral valve replacement (TMVR) is a promising strategy for patients with mitral valve disease and no surgical options. Left ventricular outflow tract (LVOT) obstruction is a life-threatening complication of TMVR. Although there are no commercially available devices to prevent LVOT obstruction, the risk of it can be reduced by careful preprocedure planning and the use of novel modifications to commercially available devices. This article summarizes current techniques to prevent LVOT obstruction with an emphasis on electrosurgical strategies.

Percutaneous Techniques, Limitations and Challenges for the Failed Surgical Mitral Intervention.

The advent of percutaneous therapies has significantly altered therapeutic options for patients with valvular heart disease. Building on the success of transcatheter aortic valve replacement, both expanded indications and purpose-built devices are now being used to address percutaneous approaches for mitral valve pathology. While surgical mitral valve repair remains the gold standard for addressing significant mitral valve pathology, there has been a progressive increase in the utilization of bioprosthetic valves despite their limited lifespan. The risks of reoperation to address mitral valve repair failure or bioprosthetic valve dysfunction is not insignificant. In light of the aging population and the potential for significant associated comorbidities, less invasive alternative techniques hold particular appeal. Utilization of commercially available transcatheter aortic valve replacement valves for failed surgical valves has been shown to have better short-term mortality than would be predicted for open reoperation. As a result, the US Food and Drug Administration approved the utilization of transcatheter mitral valve-in-valve replacement for the failed bioprosthetic valve in high surgical risk patients. Despite the favorable outcomes, transcatheter mitral valve-in-valve is not without procedural challenges and potential complications including malpositioning, embolization, paravalvular leak, and outflow tract obstruction. Awareness of these challenges, mitigation strategies, and therapeutic options is imperative to optimizing outcomes in this high-risk patient population.

Transcatheter Mitral Valve Planning and the Neo-LVOT: Utilization of Virtual Simulation Models and 3D Printing.

PURPOSE OF REVIEW: Transcatheter mitral valve replacement (TMVR) is an emerging alternative for patients with severe mitral valve regurgitation who are considered at high risk for conventional surgical options. The early clinical experience with TMVR has shown that pre-procedural planning with computed tomography (CT) is needed to mitigate the risk of potentially lethal procedural complications such as left ventricular outflow tract (LVOT) obstruction. The goal of this review is to provide an overview of key concepts relating to TMVR pre-procedural planning, with particular emphasis on imaging-based methods for predicting TMVR-related LVOT obstruction. RECENT FINDINGS: Risk of LVOT obstruction can be assessed with CT-based pre-procedural planning by using virtual device simulations to estimate the residual 'neo-LVOT' cross-sectional area which remains after device implantation. A neo-LVOT area of less than 2 cm2 is currently thought to increase the risk of obstruction; however, additional studies are needed to further validate this cutoff value. Three-dimensional printing and personalized computational simulations are also emerging as valuable tools which may offer insights not readily confered by conventional two-dimensional image analysis. The simulated neo-LVOT should be routinely assessed on pre-procedural CT when evaluating anatomical suitability for TMVR.

Validating a prediction modeling tool for left ventricular outflow tract (LVOT) obstruction after transcatheter mitral valve replacement (TMVR).

OBJECTIVE: Demonstrate proof-of-concept validation of a computed tomography (CT) computer-aided design prediction modeling tool to identify patients at risk for left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve replacement (TMVR). BACKGROUND: LVOT obstruction is a significant and even fatal consequence of TMVR. METHODS: From August 2013 to August 2017, 38 patients in 5 centers underwent TMVR with compassionate use of balloon-expandable valves for severe mitral valve dysfunction because of degenerative surgical mitral ring, bioprosthesis, or severe native mitral stenosis from to severe mitral annular calcification. All patients had preprocedural CT scans performed for anatomic screening, intraprocedural TEE and invasive hemodynamics performed. Preprocedural prediction modeling was performed utilizing computer-aided design (CAD) of the neo-LVOT post-TMVR. Post-TMVR CT scans were obtained and compared to pre-TMVR LVOT modeling datasets for validation. RESULTS: All patients underwent successful TMVR without device embolization. Seven of the 38 patients experienced LVOT obstruction, defined as an increase of ≥10 mmHg LVOT peak gradient post-TMVR. Anatomic screening using CT was validated in 20/38 patients as preprocedural predicted neo-LVOT surface area correlated well with post-TMVR measurements (R2 = 0.8169, P < 0.0001). A receiver operating curve curve found a predicted neo-LVOT surface area of ≤ 189.4 mm2 to have 100% sensitivity and 96.8% specificity for predicting TMVR-induced LVOT obstruction. CONCLUSION: CAD design and CT postprocessing are indispensable tools in predicting LVOT obstruction and necessary for anatomic screening in percutaneous TMVR.