Abstract 4136203: Risk of Mortality and Heart Failure with Myosin Inhibition Among Hypertrophic Cardiomyopathy Patients

Background: While prior studies have established that mavacamten therapy in symptomatic obstructive hypertrophic cardiomyopathy (oHCM) leads to significant clinical and functional improvement, long-term data on the effect of mavacamten on mortality and heart failure with reduced ejection fraction (HFrEF) in these patients is lacking. Methods: In this retrospective cohort study utilizing electronic health record data from the TriNetX Network, we aimed to assess the association of mavacamten therapy with mortality and HFrEF compared to medical management among patients with oHCM between 04/2022 and 04/2024. The hazard ratio (HR) and 95% confidence interval (CI) for the study outcomes were estimated by comparing propensity-score matched groups. Results: Among 47,601 adults (45.4% females; mean age: 63.5±16.6 years), 701 and 46,900 patients were included in the mavacamten and medical management groups, respectively. ( Table ) In the propensity-matched analysis, mavacamten was associated with a lower risk of mortality (HR=0.40;95%CI:0.21-0.73,p=0.002), but a similar risk of incident HFrEF (HR=1.03;95%CI:0.56-1.88,p=0.93) compared with medical management. ( Figure ) Conclusions: The current study is among the first to report improved survival with mavacamten therapy among patients with oHCM utilizing real-world data. The similar risk of HFrEF between the mavacamten and medical management cohorts highlighted in this study indicates the efficacy of the Risk Evaluation and Mitigation Strategy (REMS) program in maintaining patient safety and offsetting any potential excess risk of HFrEF.