Cardiomyopathy, Hypertrophic

Basics

Description

  • Genetic disorder affecting the sarcomere leading to asymmetric hypertrophy and fibrosis of ventricle
  • Defined as left ventricular hypertrophy in the absence of another cardiac, systemic, or metabolic cause
  • Prevalence at least 1 in 500 adults
  • Often asymptomatic and thus likely underdiagnosed (closer to 1 in 200)
  • Manifests at any age, with average age of diagnosis in 5th decade
  • Equal distribution by sex
  • Generally progressive myocardial alterations resulting in small, stiff ventricle, impaired systolic and diastolic performance, dynamic left ventricular outflow tract obstruction (LVOTO)
  • Symptoms caused by dynamic LVOTO, mitral regurgitation (MR), impaired filling, arrhythmias, ischemia related to microvascular dysfunction, metabolic and energetic abnormalities
  • 1∕3 obstructive (≥30 mm Hg LVOT gradient) at rest, 1∕3 inducible with provocation, 1∕3 nonobstructive
  • LVOT gradient changes with HR, BP, volume status, exertion, medications, oral intake
  • Common presenting conditions:
    • Lethal arrhythmias (more common in younger patients)
    • Progressive limiting symptoms secondary to LVOTO or diastolic dysfunction
    • Decompensated heart failure
    • Supraventricular arrhythmias (more common in older patients)
    • Thromboembolic events (secondary to supraventricular arrhythmias)

Etiology

  • Heterogeneous genotype
    • Variants in 1 of more than 8 genes of sarcomere-related structures implicated
    • 30–60% have identifiable genetic etiology
  • Novel (nonfamilial) variants common
  • Can have autosomal dominant inheritance
  • Incomplete penetrance, variable expression
  • Variable phenotype

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