Real-world experience in initiation of treatment with the selective cardiomyosin inhibitor mavacamten in an outpatient clinic cohort during the 12-week titration period

Introduction: Lately, mavacamten emerged as a new therapeutic option for symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM). Clinical trials revealed reduction of serum biomarkers, and left ventricular outflow tract (LVOT) obstruction, as well as an improvement in clinical symptoms and exercise capacity. Nevertheless, clinical experience and manageability of patients in a real-world setting is still lacking.

Material and methods: 22 patients with symptomatic oHCM (54.5% male, age 58.5 ± 16.2 years) and elevated LVOT gradients were started on mavacamten between March 2023 and June 2024. All patients were New York Heart Association (NYHA) class II or higher. Seven patients were excluded from primary analysis due to comedication with Angiotensin-converting-enzyme-inhibitors or Angiotensin-II receptor blockers. Cardiac imaging, laboratory work-up and clinical evaluation were assessed at three visits during the 12 weeks initiation phase; Dosing of mavacamten was adjusted according to manufacturer's recommendations.

Results: At 12 weeks, the majority of patients described a significant improvement of their quality of life. Work-up at 12 weeks revealed a significant reduction of serum biomarkers and LVOT gradients. In four patients, mavacamten needed to be temporarily paused due to clinical complaints or transient left ventricular ejection fraction deterioration below 50% with subsequent full recovery.

Conclusion: We provide first insights into the usage of mavacamten in oHCM patients during the titration period in a real-world setting. Clinical findings are in line with previous clinical trials. In accordance with current recommendations, we highlight the need for standardized follow-up of patients on mavacamten treatment.