Risk Stratification: Who is at risk for sudden cardiac arrest?
There are two populations that need to address this question a bit differently.
- Those without a diagnosis of HCM within the family.
- Those with a diagnosis of HCM, in themselves or a family member.
For the first group the HCMA suggests you review the attached PDF on “Risk Assessment for SCA” in the Young, for our purposes young is defined as under 40 years of age.
For the second group the questions get more specific.
Risk stratification is used to identify those at higher risk for sudden cardiac arrest, SCA or sudden cardiac death, SCD. When we use the phrase “Risk Stratification” we understand this is an imperfect process. The items identified have been proven by researchers to have statistical significance in helping to determine the risk of Sudden Cardiac Arrest, SCA or Sudden Cardiac Death, SCD. This process is not to assist in the determination of Risk of heart failure or progression to “Burnt Out” or “End Stage” HCM but to evaluate the risk of SCA/SCD in an individual patient. This assessment should be done upon diagnosis and again at regular intervals thought out the life of the patient, ideally annually or every other year.
Why is Risk Stratification important?
If we can identify those at risk we can offer them protection from sudden cardiac arrest, SCA with an implantable defibrillator. To complete a proper “Risk Stratification” you need to collect very specific data from various tests.
Tests Needed and Data Collected
- Echocardiogram (echo) · Measurement of the heart
- Electrocardiogram (ECG/EKG) · Measurements of electrical activity of the heart
- Holtor Monitor (24-48 hours) · History of electrical function of the heart during “normal functioning”
- Stress Test w/echo · Measurement of the heart under stress, electrically, hemodynamically & structurally
- MRI (in some cases) · For clearer picture of the heart wall and inside the walls of the heart.
What places a person at a high risk for Sudden Death?
(these are listed in no particular order)
- History of previous cardiac arrest.
- In many cases this may be the only symptom a person with HCM may have. Thankfully today AED’s (automated external defibrillators) are becoming more common place and, therefore, more people survive cardiac arrest, SCA.
- Mass Hypertrophy
- Mass Hypertrophy is measured on echocardiogram and/or MRI
- Septal measurements or left free wall measurement of 3.0 or greater are defined as “Mass Hypertrophy” (in young children this number should be discussed with a knowledgeable HCM expert as “massive hypertrophy” in a young child may be less than 3.0)
- Hypotensive Blood Pressure response on stress test
- If blood pressure drops; fails to rise or is blunted during stress test
- Family History of Sudden Death
- The death of one or more family members from HCM.
- It may not be possible to know if a family member had HCM due to lack of medical records, lack of autopsy or family dynamics. In these cases, we suggest you discuss any unexpected cardiac related deaths of family members under the age of 50 with your physician.
- History of Ventricular Arrhythmia
- Captured on Holtor monitor or telemetry.
- A Previous Cardiac Arrest
- If you have already survived a cardiac arrest this indicates that it is possible to happen again.
We know that sometimes those with no known risk factors may suffer cardiac arrest, SCA. These 6 represent what we can currently use to assess “High Risk”. Those with one or more “Risk Factors” are encouraged to discuss ICD therapy with their physician.
It is important to re-evaluate risk every 1-2 years as changes can occur at any time.
Maron, B.J. and Salberg, L. Hypertrophic Cardiomyopathy: For patients, their families and interested physicians. Blackwell Futura: 1st edition 2001,81 pages; 2nd edition 2006, 113 pages; 3rd edition pending publication 2014
Gersh, B.J., Maron, B.J., Bonow, R.O., Dearani, J.A., Fifer, M.A., Link, M.S., et al. (2011). 2011 ACCF/AHA guidelines for the diagnosis and treatment of hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation/American Heart Asociation Task Force on practice guidelines. Journal of the American College of Cardiology and Circulation, 58, e212-260.
Maron BJ, McKenna WJ, Danielson GK, Kappenberger LJ, Kuhn HJ, Seidman CE, Shah PM, Spencer WH, Spirito P, ten Cate FJ, Wigle ED. American College of Cardiology/European Society of Cardiology Clinical Expert Consensus Document on Hypertrophic Cardiomyopathy. A report of the American College of Cardiology Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines Committee to Develop an Expert Consensus Document on Hypertrophic Cardiomyopathy. J Am Coll Cardiol 2003;42:1687-1713 and Eur Heart J 2003;24:1965-1991.