Type your tag names separated by a space and hit enter

Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy is a topic covered in the 5-Minute Clinical Consult.

To view the entire topic, please or purchase a subscription.

Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:

Medicine Central

-- The first section of this topic is shown below --



  • Hypertrophic cardiomyopathy (HCM) is a form of primary myocardial hypertrophy, with or without presence of left ventricular outflow tract (LVOT) obstruction; it is characterized by four cardinal features:
    • Idiopathic LV hypertrophy (LVH) in absence of other cardiac or systemic disease causing hypertrophy of such magnitude
    • Cardiac myocyte and myofibrillar disarray
    • Familial occurrence
    • Associated sudden cardiac death (SCD)
  • System(s) affected: cardiovascular
  • Synonym(s): hypertrophic obstructive cardiomyopathy (HOCM); muscular subaortic stenosis (MSS), idiopathic hypertrophic subaortic stenosis (IHSS)


  • The disorder may present at any age.
  • It is seen in equal frequency in both sexes, although it is often underrecognized in females and African Americans.
  • Apical HCM is a variant seen more often in China and Japan (Yamaguchi apical variant).

~1% of patients with HCM die annually, but this is no different from the overall population.

Prevalence of HCM (positive phenotype or gene carrier) in the adult general population is 1:200 (1).

Etiology and Pathophysiology

  • LVH
    • ≥1 region of LV wall are thickened: classically at the basal anterior septum but may involve posterior septum or LV free wall and apex
    • Hypertrophy develops usually in adolescence, with an average 100% increase in LV mass.
  • Systolic anterior motion (SAM) of the mitral valve
    • Mitral valve abnormalities are primary manifestations of HCM: One or both leaflets may be elongated.
    • SAM is the abrupt motion of the mitral valve leaflet toward the septum, which creates dynamic LVOT obstruction in contact with the septum.
    • Caused by drag effect of the high-velocity jet caused by ejection through a narrowed LVOT and/or a Venturi phenomenon
  • Disorganized myocardial architecture
    • Myocytes and myofilaments are laid down in disorganized pattern, with increased matrix components causing myocyte disarray.
    • Microvascular disease leads to ischemia and replacement fibrosis.
  • Diastolic dysfunction
    • Result of reduced ventricular compliance; contributes predominantly to the symptoms of heart failure, such as dyspnea

  • Inherited as a mendelian autosomal dominant trait with >50% penetrance and variable expressivity
  • 11 sarcomeric gene mutations are known, including, among others, β-myosin heavy chain, myosin-binding protein C, and troponins I and T.

Risk Factors

Risk factors for SCD in patients with IHSS include the following (2):

  • A prior history of cardiac arrest or spontaneous sustained ventricular tachycardia (VT)
  • Family history of premature SCD (especially in first-degree relative[s])
  • Unexplained syncope
  • Extreme LVH measuring >30 mm
  • Hypotensive response to exercise: inability to increase by at least 20 mm Hg or a drop of at least 20 mm Hg
  • Nonsustained VT during Holter monitoring
  • Other factors that may indicate increased risk are LVOT obstruction (resting gradient >30 mm Hg), LV apical aneurysm, high-risk mutation, delayed enhancement on cardiac MRI.
  • A predicted risk ≥6% using a novel risk prediction model is classified as high risk by European Society of Cardiology (3).

General Prevention

  • Avoid strenuous exercise (particularly involving burst exertion) and heavy lifting (induces Valsalva maneuver).
  • Maintain hydration to avoid volume depletion.
  • Avoid alcohol.
  • Certain drugs, such as nitrates, digoxin, β-agonists, vasodilators, and diuretics, are best avoided, particularly in the presence of increased LVOT gradient.
  • Implantable cardioverter-defibrillator (ICD) is recommended for patients at high risk for SCD (3)[B],(4)[C].

-- To view the remaining sections of this topic, please or purchase a subscription --


Stephens, Mark B., et al., editors. "Hypertrophic Cardiomyopathy." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117664/all/Hypertrophic_Cardiomyopathy.
Hypertrophic Cardiomyopathy. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117664/all/Hypertrophic_Cardiomyopathy. Accessed April 26, 2019.
Hypertrophic Cardiomyopathy. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117664/all/Hypertrophic_Cardiomyopathy
Hypertrophic Cardiomyopathy [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 26]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117664/all/Hypertrophic_Cardiomyopathy.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Hypertrophic Cardiomyopathy ID - 117664 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117664/all/Hypertrophic_Cardiomyopathy PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -