Hypertrophic cardiomyopathy (HCM) is an inherited disorder of cardiac muscle characterized by left ventricular hypertrophy (LVH) in the absence of other cardiovascular or systemic conditions (eg, valvular heart diseases or long-standing hypertension).
The histopathologic hallmarks include myocyte hypertrophy, myocardial disarray, and fibrosis.
The prevalence of HCM is 1:500 in the general population, with at least 60% caused by mutation in one of the genes encoding different components of the sarcomere protein (see Molecular Genetics section).
It is clinically important to distinguish HCM from acquired LVH (eg, physiologic hypertrophy from athletic training, hypertensive heart disease), inherited LVH with multisystem involvement (eg, metabolic cardiomyopathy, cardiac amyloidosis) and syndromes with LVH as a presenting feature. Such diseases with similar cardiac morphologic finding can have different modes of inheritance, natural histories, and therapeutic strategies (Table 25-1).
Table 25-1Genetic Differential Diagnosis ||Download (.pdf) Table 25-1 Genetic Differential Diagnosis
|Syndrome ||Symbol of Associated Gene ||Associated Findings |
|Hypertrophic cardiomyopathy ||see Molecular Genetics section ||Isolated cardiac hypertrophy |
|Fabry disease ||GLA ||LVH, acroparesthesias, angiokeratomas, hypohidrosis, ocular involvement, renal insufficiency (proteinuria to end-stage renal disease), cerebrovascular disease |
|Danon disease ||LAMP2 (X-linked) ||LVH, ventricular pre-excitation and arrhythmias, rapid progression of heart failure, extracardiac manifestations (skeletal and neurologic) |
|PRKAG2 cardiomyopathy ||PRKAG2 ||LVH and cardiac conduction system defects (including pre-excitation) due to excessive glycogen accumulation |
|Cardiac amyloidosis (Familial) ||TTR ||LVH, sensorimotor neuropathy, autonomic neuropathy, due to amyloid infiltration |
|Friedreich ataxia (FRDA) ||FXN ||Slowly progressive ataxia of gait and limbs, depressed tendon reflexes, dysarthria, muscle weakness, spasticity, optic nerve atrophy, scoliosis, bladder dysfunction, loss of position, and vibration sense. Two-thirds of patients have cardiomyopathy |
Diagnostic Criteria and Clinical Characteristics
Diagnostic Criteria for Hypertrophic Cardiomyopathy
Presence of the following
Other findings associated with HCM include
Prominent apical impulse or lift
Brisk, occasionally bifid carotid upstroke
A harsh crescendo-decrescendo systolic murmur from ...