Early Insights on Mavacamten Usage in Canada: A Retrospective Cohort Study of the Mavacamten Patient Support Program

<h2>Abstract</h2><h3>Background</h3> There is limited real-world data on the demographic and clinical characteristics of adult patients with obstructive hypertrophic cardiomyopathy (oHCM) treated with mavacamten in Canada. <h3>Methods</h3> This was an observational retrospective cohort study on adult patients with symptomatic oHCM enrolled in the mavacamten Patient Support Program (PSP) in Canada between January 4, 2023, and April 12, 2024. Baseline demographic information, clinical characteristics, medical history, and mavacamten treatment information were collected from the PSP database. <h3>Results</h3> A total of 683 patients met the eligibility criteria for the study. The median age was 65.0 years (IQR: 57.0-73.0), 52.1% of the patients were male, and 67.1% were classified as NYHA class II at baseline. Most patients were on beta blocker monotherapy at baseline (63.7%) and data cut-off (76.3%). Almost all patients (99.4%) were initiated with 5 mg of mavacamten. The median follow-up time was 27.4 weeks (range: 1.6-70.1), and the median treatment duration was 24.6 weeks (range: 0.4-64.4). At data cut-off, 17.1% of patients were on 2.5 mg of mavacamten, 52.6% were on 5 mg, 20.2% were on 10 mg, and 2.2% were on 15 mg. Mavacamten was discontinued by 7.9% of patients, with the main reasons being side effect or adverse event (2.5%; 17/683), undisclosed physician decision (1.8%; 12/683), or lack of efficacy (0.9%; 6/683). <h3>Conclusions</h3> These early results provide the largest dataset on mavacamten utilization in the Canadian oHCM population. Baseline demographic and clinical characteristics and mavacamten dose distributions are comparable to findings from clinical trials and real-world studies. NCT06549608.