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

Hypertrophic Cardiomyopathy, Left Ventricular Outflow Obstruction, Systolic Anterior Motion

Transcatheter Mitral Valve Replacement, transcatheter electrosurgery, Septal reduction therapy, Cardiac catheterization methods, Myosin inhibitors, Myectomy, Myotomy

This is an early study of a catheter-based minimally invasive procedure called SESAME to slice thick heart muscle as described below. Excessively-thick heart muscle can cause serious heart disease, especially heart failure with preserved ejection fraction, which causes shortness of breath and heart failure symptoms such as edema (swelling) and pulmonary congestion (lung water). Specific circumstances of excessively-thick heart muscle can block outflow of blood from the main heart pumping chamber (left ventricle). We developed a catheter technique called SESAME (SEptal Scoring Along Midline Endocardium) to slice the excessively-thick heart muscle causing such problems. SESAME can be used in patients who have symptoms related to excessively-thick heart muscle in a part of the heart that restricts blood ejection from the heart; the problem is called "left ventricular outflow tract obstruction (LVOTO)." One group of patients who might benefit from SESAME suffer from a common inherited heart muscle disease called "hypertrophic cardiomyopathy (HCM)." Patients with HCM and symptoms from LVOTO can be treated with medications, open heart surgery, or catheter-based destruction of heart muscle in "alcohol septal ablation." If these treatments fail or are not suitable, then SESAME may be an option, because it resembles surgery treatment without open heart surgery. Other groups of patients that might benefit are those with heart valve diseases, of the mitral or of the aortic valve, or both, along with excessively-thick heart muscle. These patients may be poor candidates for standard surgical valve repair or replacement because of high risk of complications or death. Such patients might be eligible for non-surgical transcatheter mitral valve replacement, either standard or unapproved ("off-label") or research ("investigational"), but are poor candidates because of risk of LVOTO. Moreover, about half have LVOTO making heart valve symptoms worse. Treating the LVOTO alone may improve symptoms enough that heart valve treatment can be delayed or avoided. This is a sponsor-investigator IDE study of SESAME performed at a small number of centers that have adopted the technique in the practice of medicine, in order better to characterize how well it works and whether it is safe. 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.

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.

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