Understanding Sudden Cardiac Arrest in Young People

Cedars-Sinai investigators have identified rare genetic variants that might make some young people more likely to experience sudden cardiac arrest than others—but noted a lower rate for these variants than reported in previous studies. The findings were recently published in the peer-reviewed journal Circulation—Genomic and Precision Medicine.

Sudden cardiac arrest occurs when the heart stops beating. It causes at least 300,000 deaths in the U.S. each year. Most people die within 10 minutes of cardiac arrest. Some people survive if they can get CPR chest compressions or shocks with a defibrillator right away.

“If a person has a family member who has suffered sudden cardiac arrest, it may be helpful to undergo genetic testing to help understand one’s own risk for experiencing this dangerous condition,” said Evan Kransdorf, MD, PhD, assistant professor of Cardiology in the Smidt Heart Institute at Cedars-Sinai and senior author of the study.

Scientists are finding that some forms of sudden cardiac arrest can be prevented with an implantable defibrillator, whereas other forms of the condition aren’t responsive to interventions like defibrillators and shocks.

The condition is rare in people under the age of 35. Sudden cardiac arrest is, however, the top cause of death among young athletes.

Previous studies have found that between 12%-30% of children and young adults who experienced sudden cardiac arrest carry certain genetic variants that may have put them at higher risk for the condition.

But Kransdorf said a true figure is difficult to determine because most studies have relied on studying blood samples collected from survivors or their family members by specialized referral clinics. These samples, he said, aren’t representative of the U.S. population.

For this study, investigators analyzed blood samples collected through two ongoing community-based studies of sudden cardiac arrest: the Oregon SUDS and Ventura PRESTO studies. These are longstanding community-based programs established by Sumeet Chugh, MD, director of the Center for Cardiac Arrest Prevention in the Smidt Heart Institute and the Pauline and Harold Price Chair in Cardiac Electrophysiology Research.

As part of these studies, first responders collect blood samples from people who experience sudden cardiac arrest in Portland, Oregon, and Ventura County, California.

Investigators performed whole-genome sequencing on blood samples collected from 52 people age 21 and under who experienced sudden cardiac arrest. They found that two of the 52 young people carried genetic variants that previous studies have found to be highly associated with the condition. Four of the young people carried variants that might play a role in increasing risk for the condition, but the significance of these variants is still unknown.  

The rate of genetic variants in this population was lower than those found in other studies.  

“Additional community-based studies are going to be important to help us understand how the genetics of a diverse population compare with what has been previously established in the medical literature through studying more referral-based populations,” said Chugh.

Kransdorf, Chugh and colleagues at the Center for Cardiac Arrest Prevention are currently analyzing data from a sample of more than 3,000 people who experienced sudden cardiac arrest. They seek to better understand the extent to which genetic variants contribute to the condition.

Other Cedars-Sinai investigators who worked on the study include Lauri Holmstrom, MD, PhD, a visiting postdoctoral scientist; Kotoka Nakamura, PhD, a project scientist and team leader with the Center for Cardiac Arrest Prevention; Harpriya Chugh, a clinical research data specialist; Audrey Uy-Evanado, MD, a project scientist and team leader with the Phenotyping Core; and Faye Norby, PhD, a research assistant professor in the Department of Cardiology.

Funding: The study was funded by the National Institutes of Health (award number R01HL145675); National Heart, Lung and Blood Institute grants (R01HL147358); the Sigrid Jusélius Foundation; the Finnish Cultural Foundation; the Instrumentarium Science Foundation; the Orion Research Foundation; and the Paavo Nurmi Foundation. 

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