Use Of a Selective Cardiac Myosin Atpase Inhibitor in a Patient with Hypertrophic Cardiomyopathy with Critical Left Ventricular Outflow Tract Obstruction and Pulmonary Hypertension

Introduction. A clinical case of the use of a cardiac myosin ATPase inhibitor in a female patient with hypertrophic cardiomyopathy (HCM) characterized by critical obstruction and pulmonary hypertension (PH) is presented. Case summary . A 50-year-old female patient with obstructive HCM (pathogenic nucleotide variant p.R1420Q in the MYH7 gene) was hospitalized with paroxysmal atrial fibrillation (heart rate up to 170 bpm) and pulmonary edema. Sinus rhythm was restored by electrical cardioversion. The peak left ventricular outflow tract (LVOT) obstruction gradient was 112 mmHg, and systolic pulmonary artery pressure (sPAP) was 114 mmHg. Surgical treatment was declined due to severe pulmonary hypertension. The patient began treatment with the cardiac myosin ATPase inhibitor mavacamten at a dose of 2.5 mg, with follow-up assessments after 3.5 weeks and after 3 months of the therapy starting. As a result of treatment sPAP decreased to 71 mmHg and the peak LVOT pressure gradient (Pg max) dropped to 73 mmHg; consequently, the patient successfully underwent an extended septal myectomy. Treatment with mavacamten was discontinued. Conclusion : Treatment with the cardiac myosin ATPase inhibitor mavacamten (2.5 mg) for 3.5 months in a patient with severe obstructive HCM and significant pulmonary hypertension resulted in a reduction of systolic pulmonary artery pressure, enabling successful surgery.