Abstract 13955: Real-World Patients With Obstructive Hypertrophic Cardiomyopathy Treated With Mavacamten: A US Single Center Experience

Abstract

Background: Mavacamten, a first-in-class allosteric reversible inhibitor of cardiac myosin ATPase, was approved by the US Food and Drug Administration for the treatment of symptomatic obstructive hypertrophic cardiomyopathy (HCM) in April 2022. Purpose: To describe the characteristics of real-world patients initiated on mavacamten at a US HCM center of excellence. Methods: All patients started on mavacamten from May 2022 to February 2023 were included. Baseline demographics, clinical characteristics, and echocardiographic data, including left ventricular ejection fraction (LVEF) and left ventricular outflow tract (LVOT) gradients at rest and with Valsalva, were collected. Descriptive statistics were presented as means (standard deviations) and medians (interquartile ranges [IQRs]) or as counts and percentages as appropriate. Results: Of 45 patients initiated on mavacamten in the study period, 47% were female, 13% were non-White, and median age was 63 years (IQR 48, 70). Two-thirds were privately insured. Hypertension was common (56%), and 27% had an implantable cardioverter defibrillator. Median duration of HCM diagnosis was 6 years (IQR 4, 13), and two patients (4%) had undergone septal reduction therapy. At the time of the baseline echocardiogram prior to drug initiation, 42% had NYHA III symptoms, 56% were on background monotherapy with a beta-blocker, 24% with a nondihydropyridine calcium-channel blocker, and 20% were on both. All patients were in either sinus or an atrial-paced rhythm. Median LVEF was 69% (IQR 65, 75), and median septal wall thickness was 19 mm (IQR 18, 22). Median resting LVOT gradient was 57 mmHg (IQR 35, 80), and median Valsalva LVOT gradient was 78 mmHg (IQR 63, 91) ( Table ). Conclusions: In this single center experience of patients with obstructive HCM initiated on mavacamten, clinical characteristics were largely similar to those of patients enrolled in the phase 3 randomized trials of mavacamten, EXPLORER-HCM and VALOR-HCM.