Abstract Body (Do not enter title and authors here): Background
Treatment of left ventricular outflow tract (LVOT) obstruction involves a combination of negative inotropic agents. However, these therapies have limitations which may result in insufficient control of symptoms, leading to more invasive options such as surgical septal myectomy or septal alcohol ablation. Mavacamten, a cardiac myosin inhibitor, is currently approved for the treatment of patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM). We present a case of a patient treated with mavacamten in addition to β-blockers (BB) for management of post-TAVR LVOT obstruction.

Case
A 76 year old female with a past medical history of hypertension, severe aortic stenosis, and coronary artery disease underwent a Medtronic Evolut TAVR in March 2022. Her TTE post TAVR showed LVOT peak gradient greater than 100 mm Hg, LVEF 75% and severe eccentric mitral regurgitation secondary to systolic anterior motion (SAM) of the mitral valve (MV). After multidisciplinary discussion, the patient was discharged on maximally tolerated BB therapy. Follow up TTE showed persistent obstruction and gradients, so diltiazem was added to her regimen. Her subsequent TTE showed a peak LVOT > 100 mmHg at rest, and severe MR. Given persistent findings, she was started on mavacamten, continued on metoprolol, and tapered off of diltiazem. Her TTE two months after initiation of mavacamten revealed resolution of LVOT gradients, reduction of MR to mild and normal LV and TAVR function. She tolerated the therapy well and endorsed ongoing symptomatic improvement on subsequent follow up.

Discussion
With the increasing use of TAVR therapy, there has been a corresponding rise in cases of post-TAVR obstruction that must be managed. As demonstrated by this case, management with BB therapy alone may be suboptimal. Although mavacamten is currently approved in patients with HCM, the obstruction in post-TAVR patients is functionally similar. Thus, this medication was trialed as a supplemental treatment in this patient and yielded positive results. This case highlights the potential benefit of extending use of mavacamten alongside β-blocker therapy for this patient population and suggests the need for future studies.