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. 2024 Apr 9;83(14):1257-1272.
doi: 10.1016/j.jacc.2024.02.007. Epub 2024 Mar 11.

Transcatheter Myotomy to Reduce Left Ventricular Outflow Obstruction

Adam B Greenbaum  1 , Hiroki A Ueyama  2 , Patrick T Gleason  2 , Jaffar M Khan  3 , Christopher G Bruce  4 , Rim N Halaby  5 , Toby Rogers  6 , George S Hanzel  2 , Joe X Xie  2 , Isida Byku  2 , Robert A Guyton  2 , Kendra J Grubb  2 , John C Lisko  2 , Nikoloz Shekiladze  2 , Errol K Inci  2 , Elizabeth A Grier  2 , Gaetano Paone  2 , James M McCabe  7 , Robert J Lederman  8 , Vasilis C Babaliaros  2
Affiliations

Transcatheter Myotomy to Reduce Left Ventricular Outflow Obstruction

Adam B Greenbaum et al. J Am Coll Cardiol. .

Abstract

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 mm2 [Q1-Q3: 7-117 mm2] to 170 mm2 [Q1-Q3: 95-265 mm2]; P < 0.001; skirt-neo-LVOT 169 mm2 [Q1-Q3: 153-193 mm2] to 214 mm2 [Q1-Q3: 180-262 mm2]; 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.

Keywords: SESAME; hypertrophic cardiomyopathy; myosin inhibitors; septal reduction therapy; suicide left ventricle; transcatheter electrosurgery; transcatheter mitral valve replacement.

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Conflict of interest statement

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.

Figures

Figure 1.
Figure 1.. CT planning for SESAME.
A: Green line depicts intended trajectory to be traversed and lacerated. B: En face and C: side projection angles derived from CT to be used during fluoroscopy.
Figure 2.
Figure 2.. A representative SESAME procedure.
A: A pigtail catheter in the right sinus of Valsalva (red line) marks the medial-lateral position of the guiding catheter as it abuts the basal septum. B: Dashed red line depicts the trajectory of intramyocardial guidewire navigation. Pigtail is relocated to mark the apex. C: Guidewire is ensnared once it reenters the left ventricular cavity. D: Flying-V lacerating surface is positioned at the distal endomyocardial border, then energized during traction to create myotomy. Before lacerating, transesophageal echocardiography is used to confirm entry (E) point and (F) both depth and length of guidewire intramyocardial position.
Figure 3.
Figure 3.. Enrollment cadence and procedure indications.
Phenotype (indication) is depicted by color. Closed circles indicate 30-day survival. Asterisks indicate ventricular wall rupture. Arrows indicate VSDs. The vertical line indicates the change in intended depth from ⅔ to ½.
Figure 4.
Figure 4.. Septal thickness before and after SESAME, by phenotype.
Septal thickness (mm) measured on CT during end-diastole, before and after SESAME. Details of the measurements are shown in Supplemental Figure 1 and Supplemental Figure 2.
Figure 5.
Figure 5.. Representative evolution of splay on CT after SESAME.
Serial CT findings are shown for one representative patient after SESAME, with systole shown on the top row and end-diastole on the bottom row. The myotomy splays progressively over time.
Figure 6.
Figure 6.. NYHA class after SESAME.
The alluvial plot tracks the evolution of modified NYHA class (which incorporates death) for all patients over time. NYHA class is censored before TMVR.
Figure 7.
Figure 7.. Survival up to 30 days.
A: Stratified by phenotype. B: Stratified by urgency. Urgent or emergency cases had significantly lower survival, p<0.001.
Central illustration.
Central illustration.. SESAME transcatheter myotomy in patients.
Top panel: summary of results. Bottom panel: schematic depiction of the SESAME technique.
See this image and copyright information in PMC

References

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