Hypertrophic cardiomyopathy (HCM) is a phenotypically heterogeneous disease with a genetic basis and variable penetrance. The hallmarks of HCM include dynamic left ventricular outflow tract obstruction, typically caused by asymmetric septal hypertrophy. However, abnormal papillary muscle placement, abnormal mitral valve and subvalvular apparatus and apical hypertrophic forms have also been described. Typical medical treatment has been stagnant for decades, although there have been significant advances in surgical treatment of patients with obstructive HCM. Herein, we describe a new class of drugs targeting the specific pathophysiology of HCM.
Keywords: cardiac myosin inhibitor; hypertrophic cardiomyopathy; mavacamten.
Hypertrophic obstructive cardiomyopathy is a genetic condition that leads to increased heart muscle size. This increase in heart muscle can cause blockage of appropriate blood flow out of the heart. In such cases, current medications like β-blockers, calcium channel blockers and disopyramide can be used, but do not directly target the problem of increased heart muscle size. A new medication class, cardiac myosin inhibitors, decrease the squeezing power of the increased heart muscle to allow for more appropriate blood flow out of the heart. So far, trials have been conducted with mavacamten, with upcoming trials of aficamten (another novel cardiac myosin inhibitor). Recent trials with mavacamten have shown that this medication class has been beneficial for patients in whom other medications have failed. Some trials have also shown that by taking cardiac myosin inhibitors, patients have been able to avoid or delay surgery to correct this problem. Reassuringly, short-term data for this class of medications are positive. However, given that these medications are new, continued monitoring and research is being done to evaluate their long-term effect.