Abstract 4123391: CardioMEMS and Mavacamten: A Synergistic Approach in Managing Hypertrophic Obstructive Cardiomyopathy with HFpEF Phenotype

Introduction: Mavacamten is a cardiac myosin inhibitor that has been approved for obstructive hypertrophic cardiomyopathy (oHCM). The CardioMEMS PA (pulmonary artery) sensor allows remote pulmonary artery diastolic (PAD) pressure monitoring to adjust diuresis in heart failure with preserved ejection fraction (HFpEF). We present the case of a patient with oHCM and HFpEF where data extrapolated from CardioMEMS provided valuable insight to the hemodynamic impact of cardiac myosin inhibitors. Case: A 66-year-old female with hypertension, obesity and oHCM presented with worsening dyspnea and was evaluated for septal myectomy. However, surgery was deferred because of decompensated HFpEF, as evidenced by significant leg edema on exam, and severely elevated left and right-side filling pressure, with restrictive physiology on right heart catheterization. A CardioMEMS PA sensor was implanted to guide decongestion, however, escalation of diuresis was limited due to severe left ventricular outflow tract (LVOT) obstruction. PAD remained elevated at 20-30 mmHg. Due to the refractory LVOT obstruction and despite the use of maximally tolerated beta blockers, Mavacamten was initiated and escalated according to protocol. LVOT obstruction resolved on follow up echocardiogram. Without any adjustment in her diuretic regimen, her PAD decreased to 15-20 mmHg. On follow-up visit, the patient reported improvement in dyspnea and reduction in lower extremity edema. Discussion: Managing oHCM is challenging, particularly when complicated by HFpEF. Mavacamten has shown promise in reducing LVOT gradients and improving symptoms in oHCM. However, managing fluid status in these patients can be difficult due to the risk of exacerbating LVOT obstruction while optimizing filling pressures. Our case provides direct evidence that treating LVOT obstruction with a cardiac myosin inhibitor leads to improvement in decompensated heart failure, as evidenced by the reduction in PAD. Conclusion: Addressing LVOT obstruction is key to decongesting and managing heart failure in oHCM patients. In our case, the use of CardioMEMS PA sensor system allowed a novel perspective of assessing hemodynamic impact of cardiac myosin inhibitors.