Cardiac myosin inhibitors are a novel class of targeted therapies that reduce left ventricular hypercontractility, and as of April 2022, the first-in-class agent mavacamten is now approved by the Food and Drug Administration (FDA) for the treatment of adult patients with obstructive hypertrophic cardiomyopathy (HCM) and New York Heart Association (NYHA) class II–III symptoms. |
Angiotensin II receptor blockers (ARBs) are being studied for their potential role in reducing myocardial hypertrophy and ultimately slowing disease progression via inhibition of transforming growth factor-beta (TGF-b). |
Advances in invasive techniques including percutaneous septal radiofrequency ablation and transcatheter myotomy have provided alternative approaches for reducing left ventricular outflow tract (LVOT) obstruction in patients who are not candidates for traditional surgical septal myectomy. |
Cardiac gene replacement therapy utilizing adeno-associated viruses (AAV) has shown promise for HCM-associated myosin binding protein C3 (MYBPC3) variants in mice and human pluripotent stem cell-derived cardiomyocytes. |
Treatment of nonobstructive HCM remains a major unmet need, and there is active research into the development of cardiac mitotropes to improve myocardial metabolic efficiency. |
Introduction
Definition and Etiology
Clinical Manifestations and Phenotypes
Conventional Therapy for Hypertrophic Cardiomyopathy with Obstruction
Pharmacologic Therapy
Septal Reduction Therapy
Emerging Molecular Therapies for Hypertrophic Cardiomyopathy
Trial | Phase | Therapy | Design | N | Study Population | Aim | Result | Conclusion |
---|---|---|---|---|---|---|---|---|
Cardiac myosin inhibitors | ||||||||
PIONEER-HCM (a phase 2 open-label pilot study evaluating MYK-461 in subjects with symptomatic hypertrophic cardiomyopathy and left ventricular outflow tract obstruction) | 2 | Mavacamten | Prospective, open label | 20 | HCM diagnosis, resting LVOT gradient ≥ 30 mg Hg and post-exercise peak LVOT gradient ≥ 50 mm Hg | Change in post-exercise peak LVOT gradient, peak oxygen consumption, change in LVEF | Reduced mean post-exercise LVOT gradient, increased peak oxygen consumption, reduced resting LVEF | Mavacamten reduces LVOT obstruction and allows for improved exercise capacity |
EXPLORER-HCM (mavacamten for treatment of symptomatic obstructive hypertrophic aardiomyopathy) | 3 | Mavacamten | Prospective, randomized, double-blind | 251 | Obstructive HCM diagnosis, NYHA II or III | Improvement in peak oxygen consumption from CPET, reduction of one or more NYHA class | Reduced post-exercise LVOT gradient, increased peak oxygen consumption, 34% with improvement by at least one NYHA class | Mavacamten improved exercise capacity, LVOT obstruction and symptoms |
MAVERICK-HCM (a phase 2 study of mavacamten in adults with symptomatic nonobstructive hypertrophic cardiomyopathy) | 2 | Mavacamten | Prospective, randomized, double-blind | 59 | Nonobstructive HCM diagnosis, NYHA class II or III | Assess tolerability, safety, and efficacy in nonobstructive HCM patients | Serious adverse events in 10% on mavacamten versus 21% on placebo, five participants on mavacamten with LVEF reduced to < 45% that recovered with discontinuation of therapy, reduction in NT-proBNP and troponin I | Mavacamten is generally well tolerated, with most adverse events being considered mild or moderate. Improvement in biomarkers may suggest reduced myocardial wall stress |
VALOR-HCM (a study to evaluate mavacamten in adults with symptomatic obstructive HCM who are eligible for septal reduction therapy) | 3 | Mavacamten | Prospective, randomized, double-blind | 112 | Obstructive HCM diagnosis, referred or under active consideration within the past 12 months for SRT procedure and willing to have SRT procedure | Number of participants who were eligible to proceed with SRT, change in post-exercise LVOT gradient, NYHA class | 18% of patients on Mavacamten remained eligible for SRT compared with 77% on placebo, improvement in resting LVOT gradient, improvement by at least one NYHA class | Mavacamten improved symptoms and reduced the need for SRT among patients with obstructive HCM |
REDWOOD-HCM (randomized evaluation of dosing with CK-3773274 in obstructive outflow disease in HCM) | 2 | Aficamten | Prospective, randomized, double-blind | 41 | Obstructive HCM diagnosis, NYHA II or III, stable doses of conventional therapy | Assess safety and tolerability, change in resting and Valsalva LVOT gradient, change in LVEF, NYHA class | No serious adverse events on Aficamten, reduction in resting LVOT gradient < 30 mmHg in 93% of patients, reduction in Valsalva LVOT gradient, improvement by at least one NYHA class in most patients | Aficamten is generally well tolerated, normalizes LVOT gradients in patients with obstructive HCM, and improves symptoms |
Ion channel inhibitors | ||||||||
RESTYLE-HCM (ranolazine in patients with symptomatic hypertrophic cardiomyopathy) | 2 | Ranolazine | Prospective, randomized, double-blind | 80 | Nonobstructive HCM diagnosis | Change in peak oxygen consumption, echocardiographic lateral and septal E/E' ratio, 24 h holter arrhythmic profile, quality of life | No significant difference in peak oxygen consumption, E/E′ ratio, or quality of life. Reduction in 24-h burden of PVCs compared with placebo | Ranolazine did not improve exercise tolerance, diastolic function, or quality of life in nonobstructive HCM |
LIBERTY-HCM (the impact of late sodium current inhibition on exercise capacity in subjects with symptomatic hypertrophic cardiomyopathy) | 2 | Eleclazine | Prospective, randomized, double-blind | 172 | Obstructive HCM diagnosis, NYHA class > 1 | Change in peak oxygen consumption, quality of life, change in treadmill time to peak exercise | No difference in peak oxygen consumption, quality of life, or change in treadmill time to peak exercise | Eleclazine did not improve exercise capacity in patients with obstructive HCM |
Angiotensin II receptor blockers | ||||||||
VANISH (valsartan for attenuating disease evolution in early sarcomeric HCM) | 2 | Valsartan | Prospective, randomized, double-blind | 178 | Pathogenic or likely pathogenic HCM sarcomere mutation, NYHA class I or II, resting and provoked peak LVOT gradient < 30 mmHg | Assess safety, assess efficacy in attenuating early disease based on a composite z-score of nine distinct measures including LV wall thickness, LV mass, LA volume, NT-proBNP, and high-sensitivity troponin T | No serious adverse events. Increased composite z-score in patients on valsartan | Valsartan improved cardiac structure and function compared with placebo and may slow disease progression in early HCM |
Cardiac Myosin Inhibitors
Ion Channel Inhibitors
Angiotensin II Receptor Blockers
Advances in Septal Reduction Therapies
Percutaneous Septal Radiofrequency Ablation
Transcatheter Myotomy
Gene Therapy
Advances in Management of Nonobstructive Hypertrophic Cardiomyopathy
Future Directions and Conclusions
Trial | Phase | Therapy | Design | Study population | Aim |
---|---|---|---|---|---|
SILICOFCM (sacubitril/valsartan versus lifestyle in hypertrophic cardiomyopathy) | 2 | Sacubitril/ valsartan | Prospective, randomized, open label | Patients with both obstructive and nonobstructive HCM (NYHA Class I–III) randomized to physical activity + dietary supplement versus sacubitril/valsartan | 1°: Improvement in peak oxygen consumption 2°: Improvement in LV mass, obstruction, effect on LV function, effect on symptoms |
REDWOOD-HCM Cohort 4 (randomized evaluation of dosing with CK-274 in obstructive outflow disease in HCM) | 2 | Aficamten | Prospective, randomized, double-blind | Patients with symptomatic HCM without obstruction (rest and exercise gradients < 30 mmHg). All have NTproBNP > 300 pg/ml | 1°: safety in nonobstructive HCM 2°: dosing response relationship, effect on LV function, improvement in NTproBNP |
SEQUOIA-HCM (safety, efficacy, and quantitative understanding of obstruction impact of aficamten in HCM) | 3 | Aficamten | Prospective, randomized, double-blind | Patients with symptomatic HCM with obstruction (rest and exercise gradients ≥ 30 mmHg) | 1°: Improvement in peak oxygen consumption 2°:patient health status, NYHA class, change in post-valsalva LVOT gradients |
NIRA-HOCM (noninvasive radiation ablation in patients with hypertrophic cardiomyopathy) | – | Stereotactic body radiation therapy | Single group, open label (ten patients) | Patients with symptomatic obstructive HCM who are not candidates for SRT or with prior failed SRT | 1°: safety in obstructive HCM 2°: MACE, symptoms, change in LV wall thickness/gradient, LV function, off target effects (valvular, myocardial, and coronary artery effects) |
EMPA-REPAIR (empagliflozin in hypertrophic cardiomyopathy) | 3 | Empagliflozin | Prospective, randomized, triple-blind | Patients with HCM without severe obstruction. Excludes NYHA III–IV and severe obstruction with gradients > 50 mmHg. Also excludes patients with diabetes | 1°: Improvement in peak oxygen consumption 2°: Change in peak VO2 measured with cardiopulmonary exercise testing in patients with reduced left ventricular ejection fraction (EF < 50%) |