A 29-year-old with a dormant genetic variant has no idea they might be carrying a ticking risk factor for sudden cardiac arrest—until researchers at Cedars-Sinai's Smidt Heart Institute held up a mirror to reality. In a sweeping study of over 3,000 people who experienced sudden cardiac arrest across Portland, Oregon and Ventura County, California, scientists discovered something counterintuitive: the younger you are when your heart suddenly misfires, the more likely genetics is to blame.
Sudden cardiac arrest is an electrical malfunction that causes the heart to beat dangerously fast—and it's catastrophic. The American Heart Association reports that 90% of cases are fatal. For decades, doctors assumed it was primarily a disease of aging, triggered by narrowed or blocked arteries in older patients. But this new research rewrites that narrative for younger generations.
The Cedars-Sinai team, led by cardiologist Evan Kransdorf, MD, Ph.D., performed whole genome sequencing on blood samples from the Oregon Sudden Unexpected Death Study and the Ventura Prediction of Sudden Death in Multi-Ethnic Communities study—both created by Sumeet Chugh, MD, to untangle what triggers these deadly events. What they found was striking: the prevalence of damaging genetic variants decreased sharply with age. Among people 29 and younger who experienced sudden cardiac arrest, 10% carried a damaging genetic variant. For those aged 30 to 49, the figure dropped to 7%. By ages 50 to 69, it had fallen to 4%, and for those 70 and older, just 3% harbored these genetic variants. The researchers identified 15 genes where damaging variants can disrupt function and elevate cardiac arrest risk.
The implication is profound: a teenager or young adult who has a family member die suddenly from cardiac arrest may be living with the same vulnerability, completely unaware. Kransdorf emphasizes the practical path forward: "If you have a family member who suffered sudden cardiac arrest, it is important to undergo genetic testing to determine if you harbor a genetic variant that increases your risk of sudden cardiac arrest or other heart conditions." For those who do carry a variant, interventions are available—medications and lifestyle modifications that can meaningfully reduce their risk of experiencing this catastrophic event.
What makes this study particularly valuable is its real-world foundation. Rather than analyzing patients already being treated at a hospital, the researchers drew from community-based studies in two different regions, making the findings more representative of the broader U.S. population. This approach revealed patterns that hospital-centered research might have missed.
The research opens new doors for prevention in younger people—a population where genetic factors, not arterial disease, appear to be the dominant culprit. As scientists continue uncovering additional genes linked to sudden cardiac arrest, the window for early identification and intervention grows wider. For families carrying genetic risk, the message is clear: testing is no longer optional—it's a chance to know what's running through your veins, and to act on that knowledge before tragedy strikes.