Characteristics and Outcomes of Mavacamten Use in 2440 Patients With Obstructive Hypertrophic Cardiomyopathy

Our objective was to assess real-world outcomes and health care use associated with commercial mavacamten use in patients with obstructive hypertrophic cardiomyopathy.

We used the Symphony Dataverse to study patients receiving mavacamten between May 25, 2022 and June 30, 2024. Safety outcomes were prespecified.

We included 2440 patients and 18 494 mavacamten dispenses (63% women, median age 66 years [interquartile range {IQR}, 55-73]). Patients were followed for a median of 3037.0 days (IQR, 2808-3221) before mavacamten initiation and for 240 days (IQR, 117-407) on mavacamten. Atrial fibrillation or flutter (AF/AFL) at baseline were present in 536 (22%) of patients, whereas new-onset AF/AFL requiring therapy occurred in 125 patients (5%) and new heart failure (HF) in 100 patients (4%). During follow-up, 154 patients (6%) received new dispenses of loop diuretics, 102 (4%) oral anticoagulants, 78 (3%) amiodarone, 17 (0.7%) sotalol, and 6 (0.2%) dofetilide. There was a total of 306 patients (13%) with 428 acute care episodes (most common claims were HF (n=80, 26%), AF (n=74, 24%), and AFL (n=16, 5%)). Predictors of outcomes (new HF, new AF/AFL, ventricular tachycardia, or transient ischemic attack/stroke claim) were age at mavacamten start, obesity, transient ischemic attack/stroke history, and residence in the Western versus Southern United States.

Over an 8-month median follow-up on mavacamten in patients with obstructive hypertrophic cardiomyopathy, new AF/AFL and HF occurred in 5% and 4%, respectively. Further work is needed to better understand the expected incidence of AF/AFL, HF, and other long-term outcomes of mavacamten treatment in obstructive hypertrophic cardiomyopathy.