Hemodynamic and symptomatic response in hypertrophic obstructive cardiomyopathy patients on myosin inhibitor therapy

To provide real-world data on the symptomatic and hemodynamic response of the myosin inhibitor mavacamten in patients with hypertrophic obstructive cardiomyopathy (HOCM).

Patients with HOCM up-titrated to their final mavacamten dose were included. The final dose was defined as (i) 15 mg daily (or 5 mg for poor CYP2C19 metabolizers), (ii) a dose achieving a complete hemodynamic response (LVOT gradient <30 mmHg), or (iii) a lower dose limited by adverse effects. Final evaluation was performed 12 weeks after reaching the final dose. Symptomatic response was defined as ≥1 NYHA class improvement, and incomplete hemodynamic response as residual LVOT gradient ≥30 mmHg.

40 patients (56 ± 12 years, 78% male) were included. The LVOT gradient (rest: -25 ± 32 mmHg, p < 0.001, Valsalva: -73 ± 56 mmHg, p < 0.001) and NT-proBNP levels (-785 ± 1,122 ng/L, p < 0.001) significantly decreased during a mean follow up of 184 ± 83 days. 78% had a symptomatic response and 93% were complete hemodynamic responders. Patients with no improvement in NYHA class had a lower e' lat. (9 ± 3 cm/s vs. 6 ± 2 cm/s, p = 0.034) and less often baseline therapy with beta-blockers. Patients with incomplete hemodynamic response had a significantly higher baseline septum thickness (26.3 ± 4.9 mm vs. 19.1 ± 3.7 mm, p = 0.007) and higher LV-mass index (205 ± 63 mL/m² vs. 139 ± 31 mL/m², p = 0.038). Absolute reduction of LVOT gradients was similar in patients with and without clinical or hemodynamic response.

Clinical and hemodynamic response to mavacamten was high in this real-world cohort and comparable to pivotal trial results. Incomplete response might be related to more severe baseline disease, which needs further study.