Search

Background: Left ventricular outflow tract (LVOT) obstruction is a common, often fatal complication of transcatheter mitral valve replacement (TMVR). Laceration of the anterior mitral leaflet to prevent outflow obstruction (LAMPOON) was safe and effective at preventing LVOT obstruction at 30 days in the National Heart, Lung, and Blood Institute LAMPOON trial., Objectives: The authors report the 5-year outcomes of intentional anterior mitral leaflet laceration before SAPIEN 3 TMVR, in patients at risk of LVOT obstruction., Methods: The National Heart, Lung, and Blood Institute LAMPOON trial was a prospective, multicenter, single-arm safety and feasibility study of LAMPOON and transseptal SAPIEN 3 TMVR in annuloplasty rings (valve-in-ring) or native mitral annular calcification (MAC) (valve-in-MAC). All subjects had high predicted risk for LVOT obstruction. Subjects were not excluded for excessive frailty or comorbidity. The primary endpoints were technical success and safety at 30 days. Secondary clinical and echocardiographic endpoints were assessed at 1 year and clinical follow-up at 5 years., Results: Thirty subjects were enrolled between June 2017 and June 2018, equally between the valve-in-MAC and valve-in-ring arms. At 30 days, LAMPOON was successful in all 30 subjects, with no strokes, 1 (3%) death, and 1 (3%) moderate LVOT obstruction. Eighteen (65%) survived to 1 year, and 7 (25%) survived to 5 years. Six (20%) were hospitalized for heart failure in the first year. From baseline to 1 year, there was a 24-point improvement in Kansas City Cardiomyopathy Questionnaire score and a 60-m improvement in 6-minute walk distance. There was no significant change in N-terminal pro-brain natriuretic peptide. At 1 year, LVOT gradients remained low., Conclusions: LAMPOON enabled TMVR despite the risk for LVOT obstruction. There were no long-term complications associated with LAMPOON. The selection of inoperable patients limited assessment of long-term survival following TMVR. (NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation; NCT03015194)., Competing Interests: Funding Support and Author Disclosures This work was supported by the Division of Intramural Research, NHLBI, National Institutes of Health (Z01-HL006040), and by the intramural programs of the participating centers. The NHLBI and Edwards Lifesciences have a collaborative research and development agreement on transcatheter modification of mitral valve leaflets, including joint financial support of this study. Drs Khan, Rogers, and Lederman are coinventors on patents, assigned to the National Institutes of Health, for catheter devices to lacerate valve leaflets. Dr Khan is a proctor for Edwards Lifesciences and Medtronic; and has equity in Transmural Systems. Dr Greenbaum is a proctor for Edwards Lifesciences, Medtronic, and Abbott Vascular; and has equity in Transmural Systems and Excision Medical. Dr Babaliaros is a consultant for Edwards Lifesciences, Abbott Vascular, and Transmural Systems; and his employer has research contracts for clinical investigation of transcatheter aortic and mitral devices from Edwards Lifesciences, Abbott Vascular, Medtronic, St. Jude Medical, and Boston Scientific. Dr Rogers is a consultant for Edwards Lifesciences, Boston Scientific, Abbott, Anteris, and Medtronic; serves on advisory boards for Medtronic and Boston Scientific; and has equity in Transmural Systems. Dr Eng is on the Speakers Bureau for Edwards Lifesciences and Medtronic. Dr Foerst is a proctor for Edwards Lifesciences and Medtronic. Dr Paone is proctor for Edwards Lifesciences and has equity in Medtronic. Dr Lederman is the principal investigator on a cooperative research and development agreement between the National Institutes of Health and Edwards Lifesciences for transcatheter modification of the mitral valve. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Published by Elsevier Inc.)

Background: Left ventricular outflow tract (LVOT) obstruction is a source of morbidity in hypertrophic cardiomyopathy (HCM) and a life-threatening complication of transcatheter mitral valve replacement (TMVR) and transcatheter aortic valve replacement (TAVR). Available surgical and transcatheter approaches are limited by high surgical risk, unsuitable septal perforators, and heart block requiring permanent pacemakers., Objectives: The authors report the initial experience of a novel transcatheter electrosurgical procedure developed to mimic surgical myotomy., Methods: We used septal scoring along midline endocardium (SESAME) to treat patients, on a compassionate basis, with symptomatic LVOT obstruction or to create space to facilitate TMVR or TAVR., Results: In this single-center retrospective study between 2021 and 2023, 76 patients underwent SESAME. In total, 11 (14%) had classic HCM, and the remainder underwent SESAME to facilitate TMVR or TAVR. All had technically successful SESAME myocardial laceration. Measures to predict post-TMVR LVOT significantly improved (neo-LVOT 42 mm 2 [Q1-Q3: 7-117 mm 2 ] to 170 mm 2 [Q1-Q3: 95-265 mm 2 ]; P < 0.001; skirt-neo-LVOT 169 mm 2 [Q1-Q3: 153-193 mm 2 ] to 214 mm 2 [Q1-Q3: 180-262 mm 2 ]; P < 0.001). Among patients with HCM, SESAME significantly decreased invasive LVOT gradients (resting: 54 mm Hg [Q1-Q3: 40-70 mm Hg] to 29 mm Hg [Q1-Q3: 12-36 mm Hg]; P = 0.023; provoked 146 mm Hg [Q1-Q3: 100-180 mm Hg] to 85 mm Hg [Q1-Q3: 40-120 mm Hg]; P = 0.076). A total of 74 (97.4%) survived the procedure. Five experienced 3 of 76 (3.9%) iatrogenic ventricular septal defects that did not require repair and 3 of 76 (3.9%) ventricular free wall perforations. Neither occurred in patients treated for HCM. Permanent pacemakers were required in 4 of 76 (5.3%), including 2 after concomitant TAVR. Lacerations were stable and did not propagate after SESAME (remaining septum: 5.9 ± 3.3 mm to 6.1 ± 3.2 mm; P = 0.8)., Conclusions: With further experience, SESAME may benefit patients requiring septal reduction therapy for obstructive hypertrophic cardiomyopathy as well as those with LVOT obstruction after heart valve replacement, and/or can help facilitate transcatheter valve implantation., Competing Interests: Funding Support and Author Disclosures This work was supported by intramural funds in the Emory Structural Heart and Valve Center, Emory University Hospital Midtown; and by Z01-HL006040, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health. Drs Greenbaum, Ueyama, Gleason, Hanzel, Xie, Byku, Guyton, Grubb, Lisko, Shekiladze, Inci, Grier, Paone, and Babaliaros have received institutional research support from Abbott Vascular, Ancora Heart, Edwards Lifesciences, Gore Medical, JenaValve, Medtronic, Polares Medical, Transmural Systems, and 4C Medical. Dr Greenbaum has served as a consultant to Abbott Vascular, Edwards Lifesciences, Excision Medical, and Medtronic; and has equity interests in Transmural Systems and Excision Medical. Dr Khan has served as a proctor for Edwards Lifesciences and Medtronic; and has equity interest in Transmural Systems. Drs Khan, Rogers, and Lederman are coinventors on patent applications, assigned to the National Institutes of Health, for transcatheter electrosurgical devices. Dr Rogers has served as a consultant and proctor for Edwards Lifesciences; has served as a consultant, proctor, and advisory board member for Medtronic and Boston Scientific; and has equity interest in Transmural Systems. Dr Hanzel has served as a consultant for Medtronic. Dr Byku has served as a consultant for Edwards Lifesciences and Shockwave Medical. Dr Grubb has served on the Advisory Board of, served as a consultant for, or received honorarium from Medtronic, Boston Scientific, Abbott, 4C Medical, Ancora, and OpSens. Dr Paone has served as a consultant and proctor for Edwards Lifesciences; and has equity interest in Medtronic. Dr McCabe has served as a consultant for Edwards, Abbott, Medtronic, and Shockwave Medical; and has equity interest in Excision Medical. Dr Babaliaros has served as a consultant to Abbott Vascular, Edwards Lifesciences, and Medtronic; and has equity interest in Transmural Systems. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Published by Elsevier Inc.)

Background: Left ventricular outflow tract obstruction complicates hypertrophic cardiomyopathy and transcatheter mitral valve replacement. Septal reduction therapies including surgical myectomy and alcohol septal ablation are limited by surgical morbidity or coronary anatomy and high pacemaker rates, respectively. We developed a novel transcatheter procedure, mimicking surgical myotomy, called Septal Scoring Along the Midline Endocardium (SESAME)., Methods: SESAME was performed in 5 naive pigs and 5 pigs with percutaneous aortic banding-induced left ventricular hypertrophy. Fluoroscopy and intracardiac echocardiography guided the procedures. Coronary guiding catheters and guidewires were used to mechanically enter the basal interventricular septum. Imparting a tip bend to the guidewire enabled intramyocardial navigation with multiple df . The guidewire trajectory determined the geometry of SESAME myotomy. The myocardium was lacerated using transcatheter electrosurgery. Cardiac function and tissue characteristics were assessed by cardiac magnetic resonance at baseline, postprocedure, and at 7- or 30-day follow-up., Results: SESAME myotomy along the intended trajectory was achieved in all animals. The myocardium splayed after laceration, increasing left ventricular outflow tract area (753 to 854 mm 2 , P =0.008). Two naive pigs developed ventricular septal defects due to excessively deep lacerations in thin baseline septa. No hypertrophy model pig, with increased septal thickness and left ventricular mass compared with naive pigs, developed ventricular septal defects. One animal developed left axis deviation on ECG but no higher conduction block was seen in any animal. Coronary artery branches were intact on angiography with no infarction on cardiac magnetic resonance late gadolinium imaging. Cardiac magnetic resonance chamber volumes, function, flow, and global strain were preserved. No myocardial edema was evident on cardiac magnetic resonance T1 mapping., Conclusions: This preclinical study demonstrated feasibility of SESAME, a novel transcatheter myotomy to relieve left ventricular outflow tract obstruction. This percutaneous procedure using available devices, with a safe surgical precedent, is readily translatable into patients.

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., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Objectives: The purpose of this study was to evaluate tip-to-base intentional laceration of the anterior mitral leaflet to prevent left ventricular outflow tract obstruction (LAMPOON) in patients undergoing transcatheter mitral valve replacement (TMVR) in annuloplasty rings or surgical mitral valves., Background: LAMPOON is an effective adjunct to TMVR that prevents left ventricular outflow tract obstruction (LVOTO). Laceration is typically performed from the base to the tip of the anterior mitral leaflet. A modified laceration technique from leaflet tip to base may be effective in patients with a prosthesis that protects the aortomitral curtain., Methods: This is a multicenter, 21-patient, consecutive retrospective observational cohort. Patients underwent tip-to-base LAMPOON to prevent LVOTO and leaflet overhang, or therapeutically to lacerate a long anterior mitral leaflet risking or causing LVOTO. Outcomes were compared with findings from patients in the LAMPOON investigational device exemption trial with a prior mitral annuloplasty., Results: Twenty-one patients with a annuloplasty or valve prosthesis-protected mitral annulus underwent tip-to-base LAMPOON (19 preventive, 2 rescue). Leaflet laceration was successful in all and successfully prevented or treated LVOTO in all patients. No patients had significant LVOTO upon discharge. There were 2 cases of unintentional aortic valve injury (1 patient underwent emergency transcatheter aortic valve replacement and 1 patient underwent urgent surgical aortic valve replacement). In both cases, the patients had a supra-annular ring annuloplasty, and the retrograde aortic guiding catheter failed to insulate the guidewire lacerating surface from the aortic root. All patients survived to 30 days. Compared with classic retrograde LAMPOON, there was a trend toward shorter procedure time., Conclusions: Tip-to-base laceration is a simple, effective, and safe LAMPOON variant applicable to patients with an appropriately positioned mitral annular ring or bioprosthetic valve. Operators should take care to insulate the lacerating surface from adjacent structures., Competing Interests: Funding Support and Author Disclosures This work was supported by the Emory Structural Heart and Valve program intramural funds and by National Institutes of Health Grant No. Z01-HL006040. Dr. Lisko’s employer has contracts for BASILICA analysis with Medtronic and Edwards Lifesciences. Dr. Babaliaros has served as a consultant for Edwards Lifesciences and Abbott Vascular; has an employer with research contracts for clinical investigation of transcatheter aortic, mitral, and tricuspid devices from Edwards Lifesciences, Abbott Vascular, Medtronic, and Boston Scientific; and owns equity interest in Transmural Systems. Drs. Khan and Rogers have served as a proctor for Edwards Lifesciences and Medtronic. Drs. Khan, Lederman, and Rogers are co-inventors on patents, assigned to the National Institutes of Health, on devices for electrosurgical leaflet laceration. Dr. Paone has served as a consultant and proctor for Edwards Lifesciences. Dr. McCabe has served as consultant for Edwards Lifesciences, Boston Scientific, and Teleflex. Dr. Grubb has served as a speaker, proctor, and principal investigator for Edwards Lifesciences; served as a speaker, proctor, and advisory board member for Boston Scientific; and served as a speaker, proctor, principal investigator, advisory board member, and national principal investigator for Medtronic. Dr. Lederman has served as the principal investigator on a cooperative research and development agreement between National Institutes of Health and Edwards Lifesciences for transcatheter modification of the mitral valve. Dr. Greenbaum has served as a proctor for Edwards Lifesciences, Medtronic, and Abbott Vascular; owns an equity interest in Transmural Systems; and has an employer with research contracts for clinical investigation of transcatheter aortic, mitral, and tricuspid devices from Edwards Lifesciences, Abbott Vascular, Medtronic, and Boston Scientific. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021. Published by Elsevier Inc.)

Background: Intentional laceration of the anterior mitral leaflet (LAMPOON) is an effective adjunct to transcatheter mitral valve replacement that prevents left ventricular outflow tract (LVOT) obstruction. To date, LAMPOON has been performed in over 150 patients using a retrograde approach that can be technically challenging. A modified antegrade transseptal technique may simplify the procedure., Methods: Antegrade LAMPOON was developed and tested in nonsurvival pig experiments. Thereafter, antegrade LAMPOON was performed in patients at prohibitive risk of LVOT obstruction. Clinical, procedural, and angiographic details were abstracted from medical records of their index procedure, and were compared with findings in comparable patients at risk of fixed-LVOT obstruction in the LAMPOON investigational device exemption trial., Results: Eight patients at risk of fixed LVOT obstruction underwent antegrade LAMPOON. Leaflet traversal and laceration were technically successful in all. There were no cases of clinically significant LVOT obstruction (mean LVOT gradient at discharge: 5.4±1.4 mm Hg). One patient suffered a ventricular wire perforation, unrelated to the antegrade LAMPOON technique, and did not survive to discharge. At the time of discharge, no patients had an increase of >10 mm Hg in LVOT gradient compared with baseline. Procedure times (from traversal to transcatheter mitral valve replacement) were shorter, compared with the retrograde technique in the LAMPOON investigational device exemption trial (39±09 versus 65±35 minutes). All patients survived (8/8, 100%) the procedure, and 7/8 (88%) survived to 30 days, similar to subjects in the LAMPOON investigational device exemption trial., Conclusions: Antegrade LAMPOON is an effective, reproducible, and simplified strategy to lacerate the anterior leaflet before transcatheter mitral valve replacement. The authors recommend the technique as the new standard for LAMPOON.

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., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Left ventricular outflow tract (LVOT) obstruction is a leading cause of mortality and exclusion from transcatheter mitral valve replacement (TMVR). Intentional laceration of the anterior mitral valve leaflet to prevent LVOT obstruction (LAMPOON) is a transcatheter mimic of surgical chord-sparing leaflet resection., Objectives: The purpose of this prospective multicenter trial was to study LAMPOON with transseptal (Edwards Lifesciences, Irvine, California) TMVR in annuloplasty rings or native mitral annular calcification (MAC)., Methods: Subjects at high or extreme surgical risk and prohibitive risk of LVOT obstruction from TMVR were included. Eligibility was modified midtrial to exclude subjects with threatened LVOT obstruction from a Sapien 3 valve fabric skirt. The primary endpoint was procedure survival with successful LAMPOON, with successful TMVR, without reintervention, and with LVOT gradient <30 mm Hg ("optimal") or <50 mm Hg ("acceptable"). Secondary endpoints included 30-day mortality and major adverse cardiovascular events. There was universal source-data verification and independent monitoring. All endpoints were independently adjudicated. Central laboratories analyzed echocardiogram and CT images., Results: Between June 2017 and June 2018, 30 subjects were enrolled equally between the MAC and ring arms. LAMPOON traversal and midline laceration was successful in 100%. Procedure survival was 100%, and 30-day survival was 93%. Primary success was achieved in 73%, driven by additional procedures for paravalvular leak (10%) and high-skirt neo-LVOT gradients observed before a protocol amendment. There were no strokes., Conclusions: LAMPOON was feasible in native and annuloplasty ring anatomies in patients who were otherwise ineligible for treatment, with acceptable safety. LAMPOON was effective in preventing LVOT obstruction from TMVR. Despite LAMPOON, TMVR using Sapien 3 in annuloplasty rings and MAC still exhibits important limitations. (NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation; NCT03015194)., (Published by Elsevier Inc.)

Objectives: This study sought to use a new catheter technique to split the anterior mitral valve leaflet (AML) and prevent iatrogenic left ventricular outflow tract (LVOT) obstruction immediately before transcatheter mitral valve replacement (TMVR)., Background: LVOT obstruction is a life-threatening complication of TMVR, caused by septal displacement of the AML., Methods: The procedure was used in patients with severe mitral valve disease and prohibitive surgical risk. Patients either had prior surgical mitral valve ring (n = 3) or band annuloplasty (n = 1) or mitral annular calcification with stenosis (n = 1). Iatrogenic LVOT obstruction or transcatheter heart valve dysfunction was predicted in all based on echocardiography and computed tomography. Transfemoral coronary guiding catheters directed an electrified guidewire across the center and base of the AML toward a snare in the left atrium. The externalized guidewire loop was then electrified to lacerate the AML along the centerline from base to tip, sparing chordae, immediately before transseptal TMVR., Results: Five patients with prohibitive risk of LVOT obstruction or transcatheter heart valve dysfunction from TMVR successfully underwent LAMPOON, with longitudinal splitting of the A2 scallop of the AML, before valve implantation. Multiplane computed tomography modeling predicted hemodynamic collapse from TMVR assuming an intact AML. However, critical LVOT gradients were not seen following LAMPOON and TMVR. Doppler blood flow was seen across transcatheter heart valve struts that encroached the LVOT, because the AML was split. Transcatheter heart valve function was unimpeded., Conclusions: This novel catheter technique, which resembles surgical chord-sparing AML resection, may enable TMVR in patients with prohibitive risk of LVOT obstruction or transcatheter heart valve dysfunction., (Published by Elsevier Inc.)

Objectives: The authors propose a novel transcatheter transection of the anterior mitral leaflet to prevent iatrogenic left ventricular outflow tract (LVOT) obstruction during transcatheter mitral valve replacement (TMVR)., Background: LVOT obstruction is a life-threatening complication of TMVR caused by septal displacement of the anterior mitral leaflet., Methods: In vivo procedures in swine were guided by biplane x-ray fluoroscopy and intracardiac echocardiography. Retrograde transaortic 6-F guiding catheters straddled the anterior mitral leaflet. A stiff 0.014-inch guidewire with polymer jacket insulation was electrified and advanced from the LVOT, through the A2 leaflet base, into the left atrium. The wire was snared and externalized, forming a loop that was energized and withdrawn to lacerate the anterior mitral leaflet., Results: The anterior mitral leaflet was successfully lacerated in 7 live and 1 post-mortem swine under heparinization. Lacerations extended to 89 ± 19% of leaflet length and were located within 0.5 ± 0.4 mm of leaflet centerline. The chordae were preserved and retracted the leaflet halves away from the LVOT. LVOT narrowing after benchtop TMVR was significantly reduced with intentional laceration of the anterior mitral leaflet to prevent LVOT obstruction than without (65 ± 10% vs. 31 ± 18% of pre-implantation diameter, p < 0.01). The technique caused mean blood pressure to fall (from 54 ± 6 mm Hg to 30 ± 4 mm Hg, p < 0.01), but blood pressure remained steady until planned euthanasia. No collateral tissue injury was identified on necropsy., Conclusions: Using simple catheter techniques, the anterior mitral valve leaflet was transected. Cautiously applied in patients, this strategy can prevent anterior mitral leaflet displacement and LVOT obstruction caused by TMVR., (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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. [ABSTRACT FROM AUTHOR]