Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes abnormally thick (hypertrophied). This thickening makes it harder for the heart to pump blood effectively. It is a relatively common genetic disorder, affecting about 1 in 500 people worldwide.


  • Genetic Mutation: HCM is primarily caused by a genetic mutation passed down through families. It is considered an autosomal dominant condition, meaning that if one parent has the condition, there is a 50% chance it will be passed on to their children.
  • Spontaneous Mutation: In some cases, a person may develop HCM due to a spontaneous genetic mutation, without any family history.


  • Many people with HCM may not experience any symptoms.
  • Symptoms can vary widely and may include:
    • Shortness of Breath: Especially with exertion.
    • Chest Pain: Often occurs during physical activity or exercise.
    • Fatigue: Feeling tired all the time.
    • Palpitations: Sensation of rapid, fluttering, or pounding heartbeats.
    • Dizziness or Fainting: Particularly during physical activity


  • Physical Examination: A doctor may detect a heart murmur or other signs during a routine physical exam.
  • Echocardiogram: This is the most common test used to diagnose HCM. It uses sound waves to create detailed images of the heart’s structure and function.
  • Electrocardiogram (ECG): This can detect abnormal heart rhythms and patterns that may suggest HCM.
  • Genetic Testing: If there’s a family history of HCM, genetic testing can identify the specific genetic mutation.


  • Medications: Beta-blockers and calcium channel blockers are commonly used to help relax the heart and improve blood flow.
  • Surgery: In some cases, surgery may be necessary to remove excess heart muscle that is obstructing blood flow.
  • Implantable Cardioverter Defibrillator (ICD): For those at risk of dangerous arrhythmias, an ICD may be implanted to help regulate the heart’s rhythm.
  • Lifestyle Changes: This includes avoiding strenuous physical activity and certain competitive sports, which can increase the risk of sudden cardiac arrest.


  • Arrhythmias: Abnormal heart rhythms can be dangerous and lead to complications.
  • Heart Failure: The thickened heart muscle can make it harder for the heart to pump blood effectively.
  • Sudden Cardiac Arrest: In some cases, HCM can lead to sudden death, especially during strenuous exercise.


  • HCM varies widely in its severity. Some people may have few or no symptoms, while others may have severe complications.
  • With proper management, many people with HCM can lead normal lives.
  • Regular monitoring by a cardiologist is crucial to manage symptoms and prevent complications.



Global Prevalence:

  • Globally, HCM is estimated to affect about 1 in 500 individuals.
  • It is one of the most common inherited cardiac disorders.
  • Prevalence rates can vary depending on the population studied and the diagnostic criteria used.

Prevalence in India:

  • Data specific to India’s prevalence of HCM is not as readily available as in some other countries.
  • However, studies have suggested that the prevalence of HCM in India is likely similar to global estimates.
  • India has a large population with genetic diversity, so prevalence rates might differ among various regions and ethnic groups within the country.
  • Given the lack of large-scale epidemiological studies in India focused on HCM, the exact prevalence remains somewhat uncertain.

Factors Influencing Prevalence:

Several factors can influence the prevalence of HCM in a population:

  • Genetic Factors: HCM is an autosomal dominant genetic disorder, meaning it can be passed down through families. Certain populations with higher rates of specific genetic mutations associated with HCM may have higher prevalence rates.
  • Diagnostic Practices: Improved diagnostic techniques and increased awareness among healthcare professionals can lead to more cases being diagnosed, potentially inflating prevalence rates.
  • Population Demographics: Age, gender, and ethnicity can all play a role in the prevalence of HCM. For example, some studies suggest that HCM is more common in men and in certain ethnic groups.
  • Geographical Variations: Different regions may have different prevalence rates due to a variety of factors, including genetic predispositions and environmental influences.

Genetic Testing for HCM:

  • Identifying Mutations: Genetic testing can identify specific mutations in genes known to be associated with HCM. The most common genes involved in HCM include MYH7, MYBPC3, TNNT2, TNNI3, and others.
  • Family Screening: Once a mutation is identified in a family member with HCM, genetic testing can be used to screen other family members. This helps identify who else may be at risk for developing the condition.
  • Diagnostic Confirmation: In cases where clinical symptoms of HCM are present but not definitive, genetic testing can confirm the diagnosis.
  • Risk Assessment: Certain mutations are associated with a higher risk of complications, such as sudden cardiac death. Knowing the specific mutation can help assess the risk level for an individual.
  • Management Planning: Results from genetic testing can guide treatment and management plans. For example, individuals with certain mutations may benefit from closer monitoring or specific treatments.

Uses and Benefits:

  • Early Detection: Genetic testing allows for early detection of HCM, even before symptoms appear. This is especially crucial for at-risk family members who can then take preventive measures.
  • Personalized Medicine: With knowledge of a patient’s specific genetic mutation, treatments can be tailored to their individual needs. This can improve outcomes and reduce the risk of complications.
  • Family Planning: Individuals with HCM-causing mutations may consider genetic counseling before family planning to understand the risk of passing the mutation to their children.
  • Risk Stratification: Genetic testing can help stratify patients based on their risk profile. Those with higher-risk mutations may require more intensive monitoring and treatment.
  • Clinical Trials: Some clinical trials for HCM target specific genetic mutations. Genetic testing helps identify eligible participants for these trials, offering potential access to novel treatments.
  • Improved Prognosis: Understanding the genetic basis of HCM can provide insights into the disease progression, helping healthcare providers and patients make informed decisions about care.

Hypertrophic Cardiomyopathy: Genetic Testing and Risk Stratification.

Stafford F, Thomson K, Butters A, Ingles J.Curr Cardiol Rep. 2021 Jan 12;23(2):9. doi: 10.1007/s11886-020-01437-4.PMID: 33433738 

Hypertrophic Cardiomyopathy: An Overview of Genetics and Management.

Teekakirikul P, Zhu W, Huang HC, Fung E.Biomolecules. 2019 Dec 16;9(12):878. doi: 10.3390/biom9120878.PMID: 31888115 

Genetic Testing in Patients with Hypertrophic Cardiomyopathy.

Bonaventura J, Polakova E, Vejtasova V, Veselka J.Int J Mol Sci. 2021 Sep 27;22(19):10401. doi: 10.3390/ijms221910401.PMID: 34638741 

Clinical and ECG variables to predict the outcome of genetic testing in hypertrophic cardiomyopathy.

Robyns T, Breckpot J, Nuyens D, Vandenberk B, Corveleyn A, Kuiperi C, Van Aelst L, Van Cleemput J, Willems R.Eur J Med Genet. 2020 Mar;63(3):103754. doi: 10.1016/j.ejmg.2019.103754. Epub 2019 Sep 9.PMID: 31513939

Genetic Testing and Counseling for Hypertrophic Cardiomyopathy.

Cirino AL, Seidman CE, Ho CY.Cardiol Clin. 2019 Feb;37(1):35-43. doi: 10.1016/j.ccl.2018.08.003. Epub 2018 Oct 29.PMID: 30447714

Why should cardiologists consider genetic testing for hypertrophic cardiomyopathy?

Judge DP.JACC Heart Fail. 2015 Feb;3(2):189-91. doi: 10.1016/j.jchf.2014.09.004. Epub 2014 Oct 31.PMID: 25543975 

MYBPC3 gene variations in hypertrophic cardiomyopathy patients in India.

Tanjore RR, Rangaraju A, Kerkar PG, Calambur N, Nallari P.Can J Cardiol. 2008 Feb;24(2):127-30. doi: 10.1016/s0828-282x(08)70568-3.PMID: 18273486 

Genetic, clinical, molecular, and pathogenic aspects of the South Asian-specific polymorphic MYBPC3Δ25bp variant.

Arif M, Nabavizadeh P, Song T, Desai D, Singh R, Bazrafshan S, Kumar M, Wang Y, Gilbert RJ, Dhandapany PS, Becker RC, Kranias EG, Sadayappan S.Biophys Rev. 2020 Aug;12(4):1065-1084. doi: 10.1007/s12551-020-00725-1. Epub 2020 Jul 12.PMID: 32656747

Novel MYBPC3 Mutations in Indian Population with Cardiomyopathies.

Rani DS, Kasala A, Dhandapany PS, Muthusami U, Kunnoth S, Rathinavel A, Ayapati DR, Thangaraj K.Pharmgenomics Pers Med. 2023 Sep 20;16:883-893. doi: 10.2147/PGPM.S407179. eCollection 2023.PMID: 37750083 

Association of Cardiomyopathy With MYBPC3 D389V and MYBPC3delta25bpIntronic Deletion in South Asian Descendants.

Viswanathan SK, Puckelwartz MJ, Mehta A, Ramachandra CJA, Jagadeesan A, Fritsche-Danielson R, Bhat RV, Wong P, Kandoi S, Schwanekamp JA, Kuffel G, Pesce LL, Zilliox MJ, Durai UNB, Verma RS, Molokie RE, Suresh DP, Khoury PR, Thomas A, Sanagala T, Tang HC, Becker RC, Knöll R, Shim W, McNally EM, Sadayappan S.JAMA Cardiol. 2018 Jun 1;3(6):481-488. doi:10.1001/jamacardio.2018.0618.PMID: 29641836 

South Asian-Specific MYBPC3 (delta25bp) Deletion Carriers Display Hypercontraction and Impaired Diastolic Function Under Exercise Stress.

Bazrafshan S, Sibilia R, Girgla S, Viswanathan SK, Puckelwartz MJ, Sangha KS, Singh RR, Kakroo M, Jandarov R, Harris DM, Rubinstein J, Becker RC, McNally EM, Sadayappan S.Front Cardiovasc Med. 2021 Dec 23;8:766339. doi: 10.3389/fcvm.2021.766339. eCollection 2021.PMID: 35004883 

South Asian-Specific MYBPC3(delta25bp) Intronic Deletion and Its Role in Cardiomyopathies and Heart Failure.

Sadayappan S, Puckelwartz MJ, McNally EM.Circ Genom Precis Med. 2020 Jun;13(3):e002986. doi: 10.1161/CIRCGEN.120.002986. Epub 2020 Jun 16.PMID: 32543992