NHLBI SESAME (SEptal Scoring Along Midline Endocardium) Early Feasibility Study

Cardiac interventricular septal reduction therapies - to relieve left ventricular outflow tract obstruction from transcatheter 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 a small number of patients using off label devices. This study systematically characterizes the safety and early feasibility of SESAME at 2 enrolling site. SESAME is performed as septal reduction therapy in a heterogeneous group of subjects, including symptomatic hypertrophic cardiomyopathy and resting or provoked left ventricular outflow obstruction (LVOTO); and severe symptomatic mitral and/or aortic valve disease at high risk of standard heart surgical therapy and requiring later transcatheter heart valve implantation combined with manifest or potential LVOTO. A key goal of this study is to attempt to capture generalizable knowledge from as many patients as possible, and to add a limited number of research procedures to characterize the safety and provisional effectiveness of SESAME. Absent realistic non-clinical models of HCM or LVH combined with aortomitral disease, we believe little more information can be gleaned without clinical investigation. This protocol was revised to add a second enrolling medical center, and to focus inclusion criteria on research participants with hypertrophic cardiomyopathy (HCM). This protocol was further revised after the first subject died as a result of excessively-deep SESAME laceration. The required septal thickness for eligibility was increased from \>=12mm to \>=16mm.