Cardiac arrest in young adults typically happens for different reasons than it does in older adults, with young athletes being particularly at risk. While the most common causes of sudden cardiac arrest in people under 35 are congenital (from birth) rather than acquired, knowing the risk factors and common symptoms of heart problems can help young adults decide whether to be screened and take action to prevent sudden cardiac death.
The Causes of SCA in Young People
When cardiac arrest occurs in a young person, it can commonly be traced to one or more of the following factors.
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Genetic Heart Diseases
Congenital (from birth) heart diseases are the number one cause of sudden cardiac arrest in young adults. Sometimes, these diseases are known beforehand. Other times, there were no signs or symptoms before the cardiac arrest.
Hypertrophic Cardiomyopathy
In hypertrophic cardiomyopathy, the left ventricle of the heart thickens and becomes enlarged, making it harder for the heart to pump blood around the body. It is estimated that 2 out of 1,000 young adults have an enlarged heart muscle, most without any symptoms. Among those who are diagnosed with hypertrophic cardiomyopathy, around 1% experience sudden cardiac death each year.
Other Cardiomyopathies
There are other cardiomyopathies that can cause sudden cardiac arrest in young adults, although they aren’t seen as frequently as hypertrophic cardiomyopathy. These include:
- Dilated cardiomyopathy
- Left ventricular noncompaction cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
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Genetic Heart Abnormalities
Besides cardiomyopathies, there are several heart structure abnormalities that can limit blood flow and cause sudden cardiac arrest:
- Coronary artery abnormalities
- Genetic valve abnormalities, including mitral valve prolapse
- Structural differences in the aorta
- Ion channelopathies, including (but not limited to):
- Catecholaminergic polymorphic ventricular tachycardia
- Long QT syndrome, which causes fast and chaotic heartbeats (arrhythmias) and is linked with fainting and sudden death
- Wolfe-Parkinson-White syndrome
- Brugada syndrome
1. Myocarditis
Myocarditis is an inflammation of the heart that can lead to poor heart function. This condition can be triggered by a virus, inflammatory disease, chemicals, medications, or radiation (such as chemotherapy radiation). When the body attacks the germ, parasite, or other toxic substance in the heart, it also kills heart cells, leading to compromised heart function and arrhythmias.
2. Blunt Trauma
Sometimes, a sudden hard blow to the chest can cause cardiac arrest. If the impact occurs at very specific times in the electrical cycle, it can alter the heart’s electrical signaling and trigger sudden cardiac arrest.
3. Acquired Cardiovascular Disease
Lifestyle-related heart disease is not usually the cause of cardiac arrest in young adults, but it can still occur. We know that older adults with coronary artery disease (a buildup of plaque in the coronary arteries), heart failure, diabetes, and ventricular arrhythmias, who smoke, are obese, drink large amounts of alcohol, or lead a sedentary lifestyle are at risk for both heart attack and sudden cardiac arrest. Young people with any of these risk factors can also suffer heart events, including sudden cardiac arrest.
4. Drug Overdose
Finally, risky behaviors can also lead to sudden cardiac arrest in young adults. A study published in 2022 found that an overdose-related dispatch reason for emergency medical transport was associated with an increased likelihood of cardiac arrest on the way to the hospital.
How Common Is Sudden Cardiac Death in Young Adults?
According to research, sudden cardiac death occurs in:
- 0.6 to 6.2 out of 100,000 young people
- 1 out of 40,000 to 80,000 athletes aged 9 to 40 years
- 1 out of 8,253 elite athletes
- 0.63 out of 100,000 marathon runners (all ages)
In young athletes, sudden cardiac deaths are more common while playing team sports, whereas it happens more often in middle-aged and older adults while running. Males, black athletes, and basketball players are especially at risk. Sudden cardiac death is the number one nontraumatic cause of death in young athletes.
How Common Is Sudden Cardiac Arrest in Young People?
In contrast to sudden cardiac death (which, by definition, is fatal), out-of-hospital sudden cardiac arrest occurs much more frequently: There are around 356,000 cases of OHSCA in the United States across all age groups per year—that’s around 1 in 1,000 U.S. residents.
In long-distance runners (all ages), there are between 1 in 100,000 and 1 in 400,000 cardiac arrests per year, with prevalence increasing with age. The good news is that in cases where SCA is treated with immediate chest compressions and defibrillation with an on-site AED, survival rates for young athletes can be as high as 89%.
Main Risk Factors for Sudden Cardiac Arrest in Young Adults
The primary risk factors for SCA in young people include:
- Cardiac symptoms
- A personal or family history of heart disease, sudden infant death syndrome, sudden cardiac arrest, and sudden death
Symptoms of a heart problem that can occur before SCA can include:
- Dizziness or lightheadedness
- Fasting
- Seizure
- Shortness of breath
- Heart palpitations
- Chest pain
- Extreme tiredness
- Swelling in the lower extremities
Young athletes with cardiac symptoms or a family history of heart events are advised to have an electrocardiogram (ECG or EKG) and other tests if recommended by their doctor or cardiologist. While waiting for the results, young athletes with heart symptoms might consider avoiding or limiting strenuous activity.
What Can Young Adults Do to Lower Their Risk of Sudden Cardiac Arrest and Sudden Cardiac Death?
Some sudden cardiac arrests occur in seemingly healthy people with no warning signs, no risk factors, and no heart abnormalities. However, young people with known risk factors can be screened for heart problems and take preventative action, if needed.
Currently, the favored approach for preventing sudden cardiac death in young people with hypertrophic cardiomyopathy is to assess each patient’s individual risk using the American College of Cardiology/American Heart Association guidelines and fit high-risk patients with an implantable cardioverter defibrillator. This implanted device can intercept and reverse ventricular arrhythmias before they cause cardiac death.
Should All Young Adults Be Screened for Heart Disease?
The idea of screening young athletes for heart-related risks was the subject of a National Heart, Lung, and Blood Institute working group meeting in April 2010. The group identified gaps in the research and possible research directions to ascertain the cost-benefit ratio and utility of screening young athletes to identify risk factors for sudden cardiac death.
Some initial concerns with mandatory screening are that heart disease could be over-diagnosed due to false positives, or that young people would be medicated or excluded from sports when their heart abnormality wouldn’t otherwise have caused any issues.
At least one athlete who had been screened for heart disease and didn’t have any issues at the time of screening still suffered a sudden cardiac arrest on the field. According to a statistic from the Australian Heart Foundation, 40% of young athletes who suffer sudden cardiac death have no heart disease at all.
While screening is a good idea for young adults with symptoms or a family history of heart disease, sudden cardiac arrest, or sudden death, young adults who don’t have any risk factors don’t generally need to be tested for heart disease.
Other Ways to Lower Your Risk for Sudden Cardiac Arrest
Acquired heart disease isn’t a common cause of SCA in young adults. However, there are several things you can do to help to prevent cardiac arrest and heart disease later in life:
- Eat a heart-healthy diet
- Meet the CDC recommendations for exercise
- Don’t smoke
- Don’t drink excessive amounts of alcohol
- Don’t abuse illegal or prescription drugs
- Learn techniques for managing stress
In addition to keeping your own heart healthy, it’s important to learn how to perform hands-only cardiopulmonary resuscitation or traditional CPR and find out where your nearest automated external defibrillator (AED) is located.
AEDs, such as the Philips HeartStart FRx and LIFEPAK CR2 can often be found in hospitals, shopping malls, fitness clubs, police stations, schools, and dental offices.
If someone nearby goes into cardiac arrest, collapses, and stops breathing normally, applying immediate chest compressions and providing an electric shock within three to five minutes of the collapse could save their life.
The Most Important Things to Remember
Sudden cardiac arrest and sudden cardiac death can happen to otherwise healthy young people, especially young people who participate in team sports. While rare, sudden cardiac death still eclipses all other causes of nontraumatic death in young athletes, leading some countries and sports teams to perform routine screening for heart disease.
If you are a young person with a family history of heart disease or sudden death, or if you have experienced symptoms of a heart problem in the past, your doctor might suggest screening for heart disease so that you can make an informed decision about taking preventative measures and participating in high-intensity sports.
Whether you have risk factors or not, leading a heart-healthy lifestyle, learning CPR, and knowing where your nearest AEDs are located are the best ways to prevent yet another tragedy from sudden cardiac arrest.
