Target population for a selective cardiac myosin inhibitor in hypertrophic obstructive cardiomyopathy: Real-life estimation from the French register of hypertrophic cardiomyopathy (REMY)

[Display omitted] •We aimed to identify the real-life target population for a selective cMI in HCM.•We studied 1059 adult patients with HCM enrolled in REMY (a French HCM registry)•325 (30.7%) of these patients were potential candidates for a cMI.•9% more became eligible for a cMI during follow-up. The efficacy of current pharmacological therapies in hypertrophic cardiomyopathy is limited. A cardiac myosin inhibitor, mavacamten, has recently been approved as a first-in-class treatment for symptomatic hypertrophic obstructive cardiomyopathy. To assess the profile and burden of cardiac myosin inhibitor candidates in the hypertrophic cardiomyopathy prospective Register of hypertrophic cardiomyopathy (REMY) held by the French Society of Cardiology. Data were collected at baseline and during follow-up from patients with hypertrophic cardiomyopathy enrolled in REMY by the three largest participating centres. Among 1059 adults with hypertrophic cardiomyopathy, 461 (43.5%) had obstruction; 325 (30.7%) of these were also symptomatic, forming the “cardiac myosin inhibitor candidates” group. Baseline features of this group were: age 58±15years; male sex (n=196; 60.3%); diagnosis-to-inclusion delay 5 (1–12)years; maximum wall thickness 20±6mm; left ventricular ejection fraction 69±6%; family history of hypertrophic cardiomyopathy or sudden cardiac death (n=133; 40.9%); presence of a pathogenic sarcomere gene mutation (n=101; 31.1%); beta-blocker or verapamil treatment (n=304; 93.8%), combined with disopyramide (n=28; 8.7%); and eligibility for septal reduction therapy (n=96; 29%). At the end of a median follow-up of 66 (34–106) months, 319 (98.2%) were treated for obstruction (n=43 [13.2%] received disopyramide), 46 (14.2%) underwent septal reduction therapy and the all-cause mortality rate was 1.9/100 person-years (95% confidence interval 1.4–2.6) (46 deaths). Moreover, 41 (8.9%) patients from the initial hypertrophic obstructive cardiomyopathy group became eligible for a cardiac myosin inhibitor. In this cohort of patients with hypertrophic cardiomyopathy selected from the REMY registry, one third were eligible for a cardiac myosin inhibitor.