The American Heart Association (AHA) defines cardiac arrest as “the cessation of cardiac mechanical activity, as confirmed by the absence of signs of circulation.” Cardiac arrest is often categorized into cardiac or non-cardiac origin, and incidences are often assumed to be of cardiac origin unless there are obvious signs of trauma. Epidemiological data for cardiac arrest is often reported separately for out-of-hospital and in-hospital cardiac arrests. Occurrences of sudden cardiac arrest in children (anyone defined as anyone 18 years or younger), are commonly reported separately as well.
Out-of-Hospital Sudden Cardiac Arrest in Children
The American Heart Association calculated the incidence of out-of-hospital cardiac arrest among children 18 years and younger based upon data from an ongoing registry, the Resuscitation Outcomes Consortium (ROC). The AHA calculated the number of EMS-assessed out-of-hospital cardiac arrest in children at approximately 6,328 incidences a year in the United States. Of these SCA deaths, about half, 54%, occurred in high school students, and a vast majority, 82%, happened during physical exertion like an athletic competition or training.
The results of a sudden cardiac arrest are often lethal. The AHA reported that EMS-treated non-traumatic cardiac arrest only has a survival to hospital discharge rate of 7.3%, but this devastatingly low number can be raised when immediate treatment is given. For those SCA incidences that were witnessed and treated by a bystander, the rate of survival to hospital discharge increased to 53.3% in children with ventricular fibrillation.
In-Hospital Sudden Cardiac Arrest in Children
Because the number of children who suffer from an in-hospital cardiac arrest is so small, the American Heart Association was unable to calculate the survival rates of in-hospital SCA incidences in children. Based upon data from the Get With The Guidelines – Resuscitation Registry, there were 1,031 children that experienced an in-hospital cardiac arrest between 2001 and 2009. Of these incidences, the initial rhythm in 84.8% of cases was asystole and pulseless electrical activity. The other 15.2% of cases had an initial cardiac arrest rhythm of ventricular fibrillation and pulseless ventricular tachycardia. The risk-adjusted rate of survival to discharge in patients under 18 was 43.4% in 2009, which was vastly greater than the 14.3% rate calculated for the year 2000.
The sudden death of children is rare. Sudden cardiac death (SCD) is defined as a sudden death that is caused by a cardiovascular issue. Although the statistics vary, it is estimated that there is roughly a 0.6 incidence of pediatric SCD per 100,000 children in the United States. Of these incidences, about a quarter of the deaths occur during sports.
The most common cause of sudden cardiac death in Americans under the age of 30 is hypertrophic cardiomyopathy (HCM). As many as 1 in 500 young adults may suffer from HCM, which is often clinically silent. HCM may be caused by genetic abnormalities, and it is known to contribute to the risk of arrhythmias. HCM is usually secondary to malignant ventricular arrhythmias in cases of SCD.
Coronary artery anomalies are the next most common cause of sudden cardiac death in the youth of the United States. The most frequently occurring abnormality connected with sudden cardiac death originates from the left main coronary ostia from the right sinus of Valsalva when the coronary artery traverses between the aorta and the pulmonary artery. During physical exertion, ischemia can occur when the great vessels increase in size and compress the left main coronary artery. Coronary anomalies are often difficult to screen for during routine echocardiograms. Often, coronary artery anomalies are usually not identified unless the individual is directly evaluated because of complaints of early fatigue, angina, or exercise-induced syncope.
Dilated cardiomyopathy (DCM) is another risk factor for sudden cardiac death. DCM is defined as cardiac dilation and decreased systolic function. DCM can occur due to ischemic injury, myocarditis, or toxins, and it can also be inherited. DCM is often clinically silent in childhood, and SCD could occur before the development of other symptoms. Genetic testing can be used to diagnose DCM before heart failure occurs.
There are several rare conditions that may cause primary arrhythmias and potentially lead to sudden cardiac death in young individuals. These conditions include long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, Brugada’s syndrome, and arrhythmogenic right ventricular dysplasia. Fortunately, many of these have recurrent syncope that usually occur before the onset of more malignant symptoms or sudden cardiac death. These conditions generally require minimal evaluation through a 12-lead ECG and a personal medical history in order to be discovered.
In rare cases, a relatively small chest wall impact on an individual with a normal heart may cause commotio cordis and result in sudden cardiac death. SCD cases that result from commotio cordis generally occur in males under the age of 18. Commotio cordis is caused by a direct blow over the heart during the narrow timeframe just before the T-wave peaks.
Congenital heart disease is also associated with sudden cardiac death. There are approximately 100 incidences of SCD out of every 100,000 patient years in patients with congenital heart disease. The risk of sudden death in these individuals increases with age and time since surgery.
Screening for Risk
Sports participation is connected with many cases of sudden cardiac death in children and young adults. Because of the increased risk, it is recommended that participants should undergo a pre-participation cardiovascular screening for conditions that may contribute to an additional risk of sudden cardiac death. In the U.S., guidelines for athletic pre-screening in youth often include personal and family history with a focus on exertional chest pain, syncope, or a family history of SCD, in addition to a physical examination for blood pressure, murmurs, and stigmata of Marfan’s syndrome.
The use of ECGs in the pre-screening of athletes has been a highly debated topic. Italian athletes have undergone ECG screenings for decades, but the current reported rate of SCD in Italian athletes is not hugely different from that of the unscreened athletes in the U.S. Because of the potentially negligible differences, the high number of athletes that would require this screening, and the cost of the ECG and its interpretation, as well as the high number of false positive results that may occur in an ECG reading, it is currently not standard practice for athletes to undergo ECG screenings before participation in sports in the United States. But, the standards associated with pre-screening athletes are still being developed and may therefore change over time.
Treatment of Sudden Cardiac Arrest in Children
Although many of the underlying causes of SCAs can be treated through specific therapies, the best way to treat an SCA incidence is through CPR and automatic external defibrillators (AEDs). In order for these treatments to be effective, they must be immediate. That means that the general public, not just medical professionals, needs to undergo CPR & AED training. AEDs should also be located in places that host large numbers of people, especially when there are young athletes involved, such as in a high school or college stadium.
While sudden cardiac death is a rare occurrence in children, it is still a possibility. SCD in children is often associated with athleticism with around 25% of incidences happening during sports. A majority of children who experience an SCA have an underlying heart disease such as HCM, but the detection of these cardiac issues may not occur until it is too late. While pre-screening athletes for cardiovascular issues may help to decrease the number of young athletes who experience an SCA, this method of prevention is still being debated, and best practices are not definitively set. The best treatment for an incidence of sudden cardiac arrest is to treat the individual immediately with CPR and the use of an AED.
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. Dariush Mozaffarian, et al., “Heart Disease and Stroke Statistics – 2015 Update: A Report from the American Heart Association,” AHA Journals, (2014): e234, doi: 10.1161/CIR.0000000000000152.
. Kelly K. Gajewski, and J. Philip Saul, “Sudden Cardiac Death in Children and Adolescents (Excluding Sudden Infant Death Syndrome,” Annals of Pediatric Cardiology 3, no. 2 (2010): 107-112, doi: 10.4103/0974-2069.74035.