About HCM

What is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes abnormally thick. The thickened heart muscle can make it harder for the heart to pump blood. (Mayo Clinic)


What are the Risks of Hypertrophic Cardiomyopathy?

Cardiac arrest is the leading cause of death in young athletes. While HCM is the most common identifiable cause of sudden death in athletes, these undiscovered heart defects or overlooked heart abnormalities are rare. When these sudden deaths do occur, it’s often during physical activity, such as playing a sport.


What are the Symptoms of Hypertrophic Cardiomyopathy?

HCM often goes undetected. Many times, these deaths occur with no warning, but there are a few indications to look for. The only way to be certain is through an electrocardiogram (EKG) or echocardiogram (Echo) screening.

  • Unexplained fainting. If this occurs during physical activity, it could be a sign that there’s a problem with your heart.
  • Family history of sudden cardiac death. The other major warning sign is a family history of unexplained deaths before the age of 50. If this has occurred in your family, talk with your doctor about screening options. Hypertrophic cardiomyopathy is usually inherited.
  • Shortness of breath or chest pain. These could indicate that you’re at risk of sudden cardiac death. They could also indicate other health problems in young people, such as asthma. This can lead to an inability to exercise.
  • An arrhythmia is an abnormal heart rhythm that can feel like a flutter or a brief pause. It can cause dizziness or lightheadedness but often goes undetected. Download a PDF on the two types of arrhythmia. 

For some there are no signs or symptoms, and the disease doesn’t affect their lives. Others have severe symptoms and complications. Although rare, HCM can cause sudden cardiac arrest during very vigorous physical activity. The physical activity can trigger dangerous arrhythmias and bring on death.

Read more at Heart.org


Prevention and Treatment

There is no known cure for HCM.

For anyone with a family history or risk factors for conditions that cause sudden cardiac death, further screening is recommended. Repeat Echos and clinical screenings of family members is recommended, even when the first heart evaluation is normal. For younger family members, we recommend screenings every two years. Adults should be screened every five years.

When diagnosed with HCM, it is often recommended that you avoid most competitive sports. Competitive sports with a high level of intensity (running and sports requiring high endurance such as basketball and soccer) pose the highest level of risk.

For those already diagnosed with HCM, an implantable cardioverter-defibrillator (ICD) may be recommended by your cardiologist. This pager-sized device implanted in your chest like a pacemaker continuously monitors your heartbeat. If a life-threatening arrhythmia occurs, the ICD delivers electrical shocks to restore a normal heart rhythm. If you have an ICD, all impact sports should be avoided.


Why We Need Screenings for Young Athletes

HCM is the most common cause of sudden death in young competitive athletes in the United States, and pre-participation screening programs must be implemented to avoid these tragic fatalities. Sports participation increases the risk of sudden cardiac death in HCM patients. (See World Journal of Cardiology 2010)

The structure of screening programs is a matter of large debate, but the American Heart Association’s panel recommends a standard 14-point screening for young people. This includes asking about fainting, chest pain, excessive shortness of breath or fatigue during exercise.

Even though the NCAA currently requires every student-athlete to undergo a pre-participation evaluation conducted by a licensed medical doctor or doctor of osteopathic medicine prior to participation in an NCAA sport, high schools across the country do not.

This is where you can make a difference. By partnering with the John Lee Foundation, you will be helping to save lives by empowering communities with progressive research and frequent, more accurate, screenings for timely detection of HCM in student-athletes.

Become a Partner


A Few Statistics

  • The average age of an athlete to die from sudden cardiac arrest is 17.5 years old.
  • 90% of the victims are male. A male basketball student-athlete has an exertion-related sudden cardiac death risk of 1 in 9,000.
  • Over 50% of the victims are African-Americans.
  • Approximately 50 teenagers a year will die from HCM. That is 1 out of every 400,000 high school athletes in the United States.
  • 47 out of 182 cases of sudden death in young athletes reported in 10 years has been confirmed to be of cardiovascular cause. Almost one half (21 students) died from HCM. The most frequent sports presented in this report were basketball (23 students) and soccer (16 students).

For more statistics visit MomSteam: HCM Sudden Cardiac Death in Young Athletes or pick up one of the following:

Harmon KG, Asif IM, Maleszewski JJ, et al. Incidence, cause, and comparative frequency of sudden cardiac death in NCAA Athletes: a decade in review. Circulation 2015;132:10-9.

B.J. Maron, T.S. Haas, R.N. Caleb, et al.Incidence and cause of sudden death in US college athletes. Journal of the American College of Cardiology, 63 (2014), pp. 1636-1643


Have More Questions About HCM?

Here are a few resources to get you started


Online Resources

In-Print Resources

  • Kaltman JR, et al. Screening for sudden cardiac death in the young: Report from a National Heart, Lung, and Blood Institute Working Group. Circulation. 2011;123:1911.
  • Risgaard B. Sudden cardiac death: A nationwide cohort study among the young. Danish Medical Journal. 2016;63:5321.
  • Adabag AS,Maron BJ. Implications of arrhythmias and prevention of sudden death in hypertrophic cardiomyopathy. Ann Noninvasive Electrocardiol. 2007;12:171-180.
  • Spirito P, Autore C. Management of hypertrophic cardiomyopathy. BMJ. 2006;332:1251-1255
  • Maron BJ.Hypertrophic cardiomyopathy: a systematic review. JAMA. 2002;287:1308-1320.
  • Maron BJ. Sudden death in young athletes. N Engl J Med. 2003;349:1064-1075.
  • Maron BJ,Thompson PD, Ackerman MJ, Balady G, Berger S, Cohen D, Dimeff R, Douglas PS, Glover DW, Hutter AM Jr. Recommendations and considerations related to preparticipation screening for cardiovascular abnormalities in competitive athletes: 2007 update: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism: endorsed by the American College of Cardiology Foundation. Circulation. 2007;115:1643-1455.
  • Sorajja, R.A. Nishimura, B.J. Gersh, et al. Outcome of mildly symptomatic or asymptomatic obstructive hypertrophic cardiomyopathy.Journal of the American College of Cardiology, 54 (2009), pp. 234-241
  • 2011 ACCF/AHA guideline of the diagnosis and treatment of hypertrophic cardiomyopathy: Executive summary. A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.Journal of the American College of Cardiology, 58 (2011), pp. 2703-2738