SCA Risk Factors
Risk factors for SCA include:
- Low ejection fraction or weak heart muscle
- Prior heart attack
- Heart failure
- Abnormal heart rate or heart rhythm (arrhythmia)
- Family history of arrhythmia
- Family history of sudden cardiac death
- Congenital heart defects
- Hypertrophic cardiomyopathy (a thickened heart muscle that especially affects the ventricles)
- Viral infection in the heart
- History of syncope (fainting)
- Coronary artery disease (CAD) and risk factors for CAD, including smoking, high blood pressure, diabetes, high cholesterol, obesity, and a sedentary lifestyle
- Significant changes in blood levels of potassium and magnesium (e.g., from using diuretics)
- Recreational drug use.
Sudden cardiac arrest (SCA) occurs when the heart suddenly and unexpectedly stops. Without intervention, sudden cardiac death (SCD) occurs. SCA is the third leading cause of death in the United States (US), with over 350,000 out-of-hospital sudden cardiac arrest annually, one every 90 seconds. Sudden cardiac arrest in the young accounts for at least 7000 childhood deaths each year in the United States, representing 2% of all SCD. Conditions commonly associated with SCA include hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia, coronary artery anomalies, long QT syndrome, Wolff-Parkinson-White syndrome (WPW) and others. Many of these conditions are associated with underlying electrical or structural cardiac alternations that result in electrocardiographic (ECG/EKG) abnormalities. In this young population, it is reasonable to consider a primary prevention strategy and use an ECG to identify at-risk youth. While it is accepted that there are effective treatments for these specific cardiac conditions, the efficacy of screening tools for those at risk for SCA, particularly with an electrocardiogram, is widely debated. Identification of a predisposing disease condition allows the application of clinical guidelines and surveillance for changes in symptoms or clinical status.
Sudden cardiac arrest has a major impact upon families and communities and is a public health issue of importance. Further, SCA has a low survival rate of approximately 10% that necessitates re-evaluation of our current screening and prevention practices. Discussions of screening are often confused by the issue of whether the purpose of cardiac screening is to identify those potentially at risk for SCD or to prevent SCD or both. An effective method to identify those at risk is a first step toward the prevention of these untimely deaths.
In 2004 and 2005, the International Olympic Committee Medical Commission and European Society of Cardiology respectively recommended a screening program for young athletes based on the 12-lead ECG in addition to the history and physical exam (H&P). Since the 1970s, the Japanese school system has provided ECG screening of 1st, 7th and 10th graders. Italy requires ECG screening annually of all 12-35 year old athletes. In 2006, an Italian study reported 89% decrease in SCD, primarily from cardiomyopathies, over 25 years of their program.
Studies of youth who have experienced SCA find that approximately 50% reported antecedent symptoms and only 16% had a known positive family history. SCD often occurs without warning signs or symptoms, the first symptom in up to 50% of children will be the SCA.
In 1996, 2007, 2014, 2015, the American Heart Association (AHA) recommended a now 14-element preparticipation screening history and physical exam for high school athletes. The writers suggested that sound scientific principles should drive screening programs, but have offered no evidence regarding their current recommendations. Recent studies have shown that the AHA 14-point element is much less sensitive, specific and accurate than using an ECG.
Numerous studies have shown that the ECG, in at least two-thirds to three-quarters of conditions associated with SCA, can be used to identify these conditions with catecholaminergic polymorphic ventricular tachycardia (CPVT), coronary artery anomalies, and aortic dilation associated with Marfan syndrome being the most notable exceptions.
It should be noted that an ECG is generally a screening test, not a diagnostic test, and should result in referral to a cardiac specialist with other testing at their discretion. On the other hand, there is no evidence that the current screening practice of using H&P alone is decreasing the overall occurrence of SCD. Multiple clinical reports indicate that death in individuals with SCD related conditions can be prevented once treatment using standard medical practices is initiated.
Screening of all children at periodic intervals will result in identification of many who have undiagnosed conditions that can be associated with sudden cardiac death and allow clinical evaluation, surveillance and treatment, potentially saving lives.
The goal of decreasing SCD in youth has not been realized. Support of screening efforts with sound scientific rigor should be developed to determine the best methods to identify young children before they experience an SCA or SCD. Screening efforts should be focused on quality, regardless of the screening methodology used.
Society will need to determine if it is justified to wait for an SCA in youth in the 30–50% who will present in this manner or be more proactive and try to identify those at risk, when possible, with an ECG or other testing.
By Victoria L. Vetter, MD, FAAP, FACC, Children's Hospital of Philadelphia
CPR & AED Training
Victims of sudden cardiac arrest need immediate CPR and treatment with AEDs (automated external defibrillators). CPR/AED training is available through several national organizations, plus local hospitals, fire departments and EMS agencies.
To find training in your area, visit the following websites or contact local resources.
- American Heart Association
- American Red Cross
- American Safety and Health Institute/Medic First Aid
- Emergency Care and Safety Institute
- National Safety Council.
Information about how to provide CPR is also available through the University of Washington School of Medicine.
For videos on how to perform Hands-Only CPR, visit:
- American Heart Association
- American Red Cross
- New York-Presbyterian Hospital
- University of Michigan.
For additional videos, visit the Sudden Cardiac Arrest Foundation YouTube Channel.
Learn CPR for someone you love.