A major new study from researchers at Cedars-Sinai has found that younger people who suffer sudden cardiac arrest are much more likely to have a genetic cause behind the condition than older adults.
The findings suggest that genetic testing could help identify people at risk before a deadly event happens.
The research was published in the medical journal JACC: Clinical Electrophysiology and adds to growing evidence that inherited heart conditions play an important role in sudden cardiac arrest, especially in younger age groups.
Sudden cardiac arrest happens when the heart suddenly stops beating properly because of a dangerous electrical problem. The heart may begin beating extremely fast or chaotically, preventing blood from reaching the brain and other organs. Without immediate treatment, the condition is often fatal within minutes.
Although people sometimes confuse sudden cardiac arrest with a heart attack, the two are not the same. A heart attack usually happens when blood flow to the heart becomes blocked. Sudden cardiac arrest involves the heart’s electrical system suddenly failing.
According to the American Heart Association, sudden cardiac arrest is fatal in about 90% of cases. Even when emergency medical treatment is available, survival rates remain low.
Researchers say understanding who is at risk could save many lives.
Lead author Evan Kransdorf explained that people with a family history of sudden cardiac arrest should consider genetic testing.
He said discovering harmful genetic variants early may allow doctors to recommend treatments, medications, lifestyle changes, or close monitoring that could lower the chance of a life-threatening event.
The research team analyzed blood samples from more than 3,000 people who experienced sudden cardiac arrest in Portland, Oregon, and Ventura County, California. The samples came from two major ongoing research projects: the Oregon Sudden Unexpected Death Study and the Ventura Prediction of Sudden Death in Multi-Ethnic Communities study.
Both projects were created by senior researcher Sumeet Chugh to better understand why sudden cardiac arrest happens and how to prevent it.
The researchers used a technique called whole genome sequencing, which studies a person’s complete genetic code. This technology allows scientists to search for harmful changes in genes that may increase disease risk.
The team identified 15 genes linked to sudden cardiac arrest risk. Harmful variants in these genes can interfere with normal heart function and increase the likelihood of dangerous electrical problems in the heart.
One of the most important findings was the strong connection between age and genetic risk.
Among people aged 29 and younger who experienced sudden cardiac arrest, 10% carried harmful genetic variants linked to the condition.
In adults aged 30 to 49, about 7% carried these variants. In people aged 50 to 69, the number dropped to 4%. Among adults aged 70 and older, only 3% carried the harmful variants.
The researchers believe this pattern exists because sudden cardiac arrest in younger people is more likely to result from inherited heart conditions, while in older adults it is more commonly caused by blocked or narrowed blood vessels related to aging and heart disease.
This means that younger patients experiencing sudden cardiac arrest may benefit particularly strongly from genetic testing and family screening.
Scientists say the findings may also help explain some tragic cases where apparently healthy young people suddenly collapse during sports, exercise, or everyday activities.
Many inherited heart conditions can remain hidden for years without obvious symptoms. Some people may only experience mild warning signs such as fainting, heart palpitations, chest discomfort, or dizziness before a major event occurs. Others may have no symptoms at all.
Researchers hope that broader genetic screening could eventually identify at-risk individuals before sudden cardiac arrest happens.
The study is considered especially valuable because it examined people from large community populations rather than only patients already receiving care at specialized medical centers. Researchers say this makes the findings more representative of the general U.S. population.
Senior author Chugh explained that studying entire communities provides a clearer picture of sudden cardiac arrest risk across different ethnic and demographic groups.
The researchers also emphasized that many genes involved in sudden cardiac arrest risk may still remain undiscovered. Future research may uncover additional genetic factors and improve doctors’ ability to predict who faces the highest risk.
The findings come at a time when genetic testing technology is becoming faster, cheaper, and more widely available. However, experts caution that genetic testing also raises important ethical and emotional questions for families, especially when harmful variants are discovered in otherwise healthy individuals.
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Source: Cedars-Sinai.
