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Content Update

EXPLORER-LTE Cohort of the MAVA-LTE Study

Interim efficacy and safety results have been reported for the EXPLORER-LTE cohort of the MAVA-LTE study of mavacamten in 231 of the original 244 patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) enrolled in the placebo-controlled EXPLORER-HCM trial. Read More

Content Update

VALOR-HCM: Mavacamten in Adults with Symptomatic Obstructive HCM Eligible for Septal Reduction Therapy

The VALOR-HCM trial was a randomized, double blinded, placebo-controlled study of whether mavacamten (a novel oral allosteric modulator of cardiac myosin) improved symptoms and significantly reduced eligibility for requiring septal reduction therapy (SRT) among 112 symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM; maximum septal wall thickness on echocardiography ≥ 15 mm or ≥ 13 mm with family history) who were referred for SRT. Read More

Chapter Summary

This chapter discusses the epidemiology, pathophysiology, diagnosis, and management of hypertrophic cardiomyopathy (HCM), a common inherited condition. In ~50% of cases, HCM is due to a pathogenic variant in a sarcomere protein gene (see Fuster and Hurst’s Central Illustration) and is inherited as an autosomal dominant trait with incomplete penetrance. Phenocopies should be actively ruled out during diagnostic work-up. The pathophysiology is complex and consists of multiple interrelated factors, including myocardial ischemia, diastolic (and rarely systolic) dysfunction, left ventricular outflow tract (and/or midcavity) obstruction (LVOTO), mitral regurgitation, and atrial fibrillation. Symptoms related to LVOTO are managed medically in the first instance but may require invasive treatment with surgical septal myectomy or alcohol septal ablation. Heart failure is an important cause of death and is treated according to the current standard recommendations. Atrial fibrillation carries a high thromboembolic risk and mandates anticoagulation. Defibrillators are the only effective protection from sudden death in high-risk patients.

eFig 42-01 Chapter 42: Hypertrophic Cardiomyopathy


Hypertrophic cardiomyopathy (HCM) is defined as left ventricular (LV) hypertrophy in the absence of abnormal loading conditions, such as severe hypertension or valve disease, sufficient to cause the observed phenotype.1,2 Echocardiographic studies in healthy young adults suggest a prevalence of around 1:500, with no significant differences across ethnicities or geographical location. Extrapolation based on the autosomal genetic basis of disease has led to speculation that this may be an underestimate.3 Conversely, studies based on electronic health records indicate that the clinically evident prevalence may be closer to 1:2500.4 Large cohorts have a male predominance of 60% to 65%. Ventricular hypertrophy most frequently develops during periods of rapid somatic growth, but can appear de novo at any time from infancy to old age.5,6

The term hypertrophic cardiomyopathy does not indicate a single condition, but rather describes a phenotype that is shared by a range of disorders that can be grouped into familial/genetic and nonfamilial/nongenetic subtypes.7,8 In ...

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