NHLBI SESAME (SEptal Scoring Along Midline Endocardium) Multi-Center Prospective Study Using Improvised Off-Label Devices

Cardiac septal reduction therapies - to relieve left ventricular outflow tract obstruction from transcatheter mitral valve replacement or hypertrophic cardiomyopathy - have inherent limitations including dependence on coronary anatomy, high pacemaker implantation rate, and surgical morbidity. We developed a novel transcatheter ventricular myotomy called SEptal Scoring Along the Midline Endocardium (SESAME) that relies on intramyocardial guidewire navigation and transcatheter electrosurgery. SESAME has been performed on hundreds of patients worldwide using improvised (off-label and bedside-modified commercially available) devices. Recent benchtop refinements in SESAME technique, using improvised devices, are predicted to reduce the likelihood of serious complications such as ventricular perforation, iatrogenic ventricular septal defect, and death. This sponsor-investigator IDE study systematically characterizes the safety and outcomes of SESAME at up to 10 enrolling sites. SESAME is performed as septal reduction therapy in a heterogeneous group of participants, including (1) symptomatic hypertrophic cardiomyopathy with resting or provoked left ventricular outflow obstruction (LVOTO); and (2) severe symptomatic mitral valve disease at high risk of standard heart surgical therapy and requiring later transcatheter mitral valve implantation combined with manifest or potential LVOTO. This study attempts to capture generalizable knowledge from as many patients as possible who undergo SESAME, and to add a limited number of research procedures to characterize the safety and provisional effectiveness of SESAME. Participating centers already perform SESAME in the practice of medicine using improvised, off-label devices. This protocol allows prospective oversight, standardized technique constraints, central imaging review, independent monitoring, and formal safety adjudication. In addition, the investigational protocol does not function as the gatekeeper for access to SESAME. The investigators are not affiliated with the guidewire manufacturer and do not seek marketing approval or clearance for SESAME.