Researchers have discovered that genes may play a much larger role in sudden cardiac arrest among young people than previously understood.
A new study led by scientists at Cedars-Sinai found that younger people who experience sudden cardiac arrest are significantly more likely to carry dangerous inherited genetic variants compared with older adults.
The findings were published in JACC: Clinical Electrophysiology and may change how doctors identify people at risk for this often fatal condition.
Sudden cardiac arrest occurs when the heart’s electrical system suddenly malfunctions, causing the heart to stop pumping blood effectively. Without immediate treatment such as CPR or defibrillation, death can happen within minutes.
Unlike a heart attack, which usually results from blocked blood flow to the heart muscle, sudden cardiac arrest involves abnormal electrical activity inside the heart itself. The condition can affect people of all ages, including athletes and individuals who previously seemed healthy.
The American Heart Association estimates that sudden cardiac arrest is fatal in roughly 90% of cases. Because survival rates are so low, scientists have focused heavily on finding ways to identify high-risk people before a deadly event occurs.
The new study examined blood samples from more than 3,000 people who had experienced sudden cardiac arrest. Participants came from Portland, Oregon, and Ventura County, California, as part of two long-running research projects studying sudden death in communities.
The researchers used whole genome sequencing technology, which allows scientists to examine a person’s complete DNA sequence. This method can identify harmful changes in genes that may contribute to disease.
Scientists discovered 15 genes containing damaging variants linked to sudden cardiac arrest risk. These variants can disrupt normal heart function and increase the risk of dangerous rhythm abnormalities.
The strongest pattern emerged when researchers looked at age differences.
Among patients aged 29 and younger, 10% carried harmful genetic variants associated with sudden cardiac arrest. In adults aged 30 to 49, the percentage fell to 7%. In the 50-to-69 age group, only 4% carried the variants. For people aged 70 and older, the number dropped to just 3%.
Researchers believe these findings show that genetics plays a much bigger role in sudden cardiac arrest among younger people.
Lead author Evan Kransdorf said people with a family history of sudden cardiac arrest should strongly consider genetic testing.
If harmful genetic variants are discovered, doctors may be able to lower risk through medications, monitoring, implanted devices, or lifestyle adjustments.
Many inherited heart conditions can remain silent for years. Some individuals may experience only mild symptoms such as fainting, dizziness, chest pain, rapid heartbeat, or shortness of breath before a dangerous event occurs. Others may never show warning signs.
The researchers explained that older adults are more likely to experience sudden cardiac arrest due to blocked arteries and other forms of heart disease linked to aging rather than inherited genetic problems.
This difference may explain why harmful genetic variants were found much more frequently in younger patients.
The study also highlights the importance of family screening. When one person is found to carry a dangerous genetic variant, relatives may also carry the same mutation without knowing it.
Early identification may allow family members to receive medical care before symptoms appear.
Senior researcher Sumeet Chugh noted that the study provides a broader view of sudden cardiac arrest risk because it examined entire communities instead of only patients treated at specialized hospitals.
Researchers believe this makes the findings more representative of the overall U.S. population.
The team emphasized that many genetic causes of sudden cardiac arrest likely remain undiscovered. As genetic technology improves, scientists expect to identify additional genes involved in abnormal heart rhythms and sudden death.
The findings also reflect the growing role of genetics in modern medicine. Doctors increasingly use genetic information to guide treatment decisions, estimate disease risk, and develop personalized prevention plans.
However, experts caution that carrying a harmful genetic variant does not guarantee someone will experience sudden cardiac arrest. Many people with genetic risk factors may never develop serious symptoms. Environmental factors, lifestyle, exercise, and other health conditions may also influence risk.
Researchers hope future studies will help doctors better understand how genetic variants interact with other factors to trigger sudden cardiac arrest.
The study may also influence future public health policies surrounding genetic testing and heart screening, especially for younger individuals with a family history of sudden unexplained death.
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