Understanding Hypertrophic
Cardiomyopath‌y

Background

HCM is a chronic, progressive cardiovascular disease that can leave patients with debilitating symptoms and potentially life-threatening complications1

HCM is characterized by unexplained left ventricular hypertrophy (end-diastolic wall thickness ≥15 mm anywhere in the left ventricle or 13–14 mm with a family history of HCM or positive genetic test).2,3

HCM is classified into two main subtypes: obstructive (oHCM) and nonobstructive (nHCM). Determining the subtype based on the left ventricular outflow tract (LVOT) gradient is essential for guiding management strategies. Obstruction is defined as a peak LVOT gradient >30 mmHg, with or without provocation.4,5

In addition to hypercontractility and impaired diastolic function, HCM can negatively impact cardiac structure and contribute to dysfunction.2,3

Key Features in Assessing HCM

Key features in assessing HCM
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Prevalence

HCM is the most common inherited heart disease, yet many patients remain undiagnosed8

The reported prevalence of HCM ranges from

1 in 200 to 1 in 500

people in the general population2,9,10*†

* The CARDIA study (published in 1995) was a multicenter, US-population-based echocardiography study of 4111 subjects (aged 23-35) that identified the prevalence of HCM as 1:500 people in the general population.9
† The 2015 Semsarian publication identified that the prevalence of HCM gene carriers could be as high as 1:200.10

HCM can be genetically passed down from one generation to the next in some patients.2  HCM frequently remains undiagnosed until young adulthood and even as late as midlife, allowing disease progression to go unmitigated.11

It has been estimated that ~700,000 people in the US have HCM, yet

~85% of patients in the US remain undiagnosed12‡

1 in 10 patients are only diagnosed after a cardiac event13§

‡ Based on a 2013 ICD-9 claims database analysis (N=169,089,614) that estimated/concluded: 1. ~600,000 patients with undiagnosed HCM (based on analysis’ assumption that 1 in 500 prevalence represents clinically unrecognized cases), 2. ~100,000 patients diagnosed HCM (based on 2021 US Census population and the ratio of 332,330,571 patients with a claim for HCM over the total N, stratified by age/gender), and 3. ~700,000 overall US estimated prevalence of HCM.12
§ Based on a study analyzing 711 patients diagnosed with HCM.3
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Patient Impact

Undiagnosed HCM can progress to serious, life-threatening complications3

HCM Can Have Critical Repercussions3

The natural history of HCM can include serious complications. In 2 studies with a combined ~5500 patients, mortality rates were found to be 3-4x higher for patients (aged 20-29 and 50-60 years) with HCM than those of the general public.4,14¶#

Heart failure

22%-43%

estimated prevalence4,14¶

AFib

19%–20%

estimated prevalence4,14¶

Stroke

4%–5%

estimated prevalence14,15¶

Based on a retrospective analysis from the SHaRe registry (N=4591) and a prospective, single-center US observational study from 2003–2013 (N=1000).14
# In US sites using international registry data from 1960–2016 (N=4591), mortality was >4x higher for patients aged 20–29 years and ≥3x higher for patients aged 50–69 years.4,14

HCM Can Impact More Than the Heart16

HCM can be a debilitating and life-altering disease. Patients tend to adapt their lifestyle to accommodate their symptoms.
Person walking

Physical impacts

  • Walking
  • Exercising
  • Day-to-day activities
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Thinking brain

Emotional impacts

  • Mood
  • Anxiety
  • Depression
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HCM Patients

Social impacts

  • Work status
  • Relationship with family and friends
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Signs & Symptoms

Dr. Owens and Dr. Silvestri discuss why HCM is often described as a masquerader.

Watch a video on the hidden challenges in diagnosing HCM

Clinical markers and cardiac imaging can aid in distinguishing HCM from phenotypic mimickers causing physiologic LVH and similar, nonspecific symptoms.2,6

HCM and Cardiovascular Symptoms Overlap

CAD=coronary artery disease; COPD=chronic obstructive pulmonary disease.

When patients experience fatigue, chest pain, dyspnea (especially exertional), palpitations, and/or syncope, consider HCM.17

REFERENCES:

  1. Naidu SS, ed. Hypertrophic Cardiomyopathy. London, Eng: Springer-Verlag; 2015.
  2. Ommen SR, Ho CY, Asif IM, et al. 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the management of hypertrophic cardiomyopathy: a report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines. Circulation. 2024;149(23):e1239-e1311.
  3. Naidu SS, Sutton MB, Gao W, et al. Frequency and clinicoeconomic impact of delays to definitive diagnosis of obstructive hypertrophic cardiomyopathy in the United States. J Med Econ. 2023;26(1):682-690.
  4. Rowin EJ, Maron MS, Chan RH, et al. Interaction of adverse disease related pathways in hypertrophic cardiomyopathy. Am J Cardiol. 2017;120(12):2256-2264.
  5. Stanford Health Care. Hypertrophic cardiomyopathy. Accessed June 14, 2021. https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/hypertrophic-cardiomyopathy.html
  6. Mitchell CC, Frye C, Jonkowski M, et al. A practical approach to echocardiographic imaging in patients with hypertrophic cardiomyopathy. J Am Soc Echocardiogr. 2023;36(9):913-932.
  7. Nagueh SF, Phelan D, Abraham T, et al. Recommendations for multimodality cardiovascular imaging of patients with hypertrophic cardiomyopathy: an update from the American Society of Echocardiography, in collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography. J Am Soc Echocardiogr. 2022;35(6):533-569.
  8. Maron BJ, Rowin EJ, Maron MS. Global burden of hypertrophic cardiomyopathy. JACC Heart Fail. 2018;6(5):376-378.
  9. Maron BJ, Gardin JM, Flack JM, Gidding SS, Kurosaki TT, Bild DE. Prevalence of hypertrophic cardiomyopathy in a general population of young adults. Echocardiographic analysis of 4111 subjects in the CARDIA study. Circulation. 1995;92(4):785-789.
  10. Semsarian C, Ingles J, Maron MS, Maron BJ. New perspectives on the prevalence of hypertrophic cardiomyopathy. J Am Coll Cardiol. 2015;65(12):1249-1254.
  11. Jacobs C. Hypertrophic cardiomyopathy in adults: an overview. J Am Assoc Nurse Pract. 2014;26(9):465-470.
  12. Maron MS, Hellawell JL, Lucove JC, Farzaneh-Far R, Olivotto I. Occurrence of clinically diagnosed hypertrophic cardiomyopathy in the United States. Am J Cardiol. 2016;117(10):1651-1654.
  13. Adabag AS, Kuskowski MA, Maron BJ. Determinants for clinical diagnosis of hypertrophic cardiomyopathy. Am J Cardiol. 2006;98(11):1507-1511.
  14. Ho CY, Day SM, Ashley EA, et al; Genotype and lifetime burden of disease in hypertrophic cardiomyopathy: insights from the Sarcomeric Human Cardiomyopathy Registry (SHaRe). Circulation. 2018;138(14):1387-1398.
  15. Maron BJ, Olivotto I, Bellone P, et al. Clinical profile of stroke in 900 patients with hypertrophic cardiomyopathy. J Am Coll Cardiol. 2002;39(2):301-307.
  16. Zaiser E, Sehnert AJ, Duenas A, Saberi S, Brookes E, Reaney M. Patient experiences with hypertrophic cardiomyopathy: a conceptual model of symptoms and impacts on quality of life. J Patient Rep Outcomes. 2020;4(1):102.
  17. University of Maryland Medical Center. Hypertrophic cardiomyopathy types, symptoms and causes. Accessed October 15, 2025. https://www.umms.org/ummc/health-services/heart-vascular/services/hypertrophic-cardiomyopathy/types-symptoms-causes
References
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