Gilliam, 32, suffered sudden cardiac arrest, an electrical malfunction of the heart that causes it to abruptly stop beating. The odds were stacked against him: Sudden cardiac arrest kills about 90% of those who experience it outside of a hospital. Survival depended on a chain of people acting within minutes.

A fellow dancer immediately started CPR. Other dancers ran out of the dance studio in search of an automated external defibrillator (AED) and found one at a nearby dentist’s office. A speech pathologist who had just completed CPR recertification and happened to be nearby used the AED to revive Gilliam’s heartbeat.

Paramedics then rushed Gilliam to the Cedars-Sinai Emergency Department, where he had another cardiac arrest. Surgeons placed Gilliam on extracorporeal membrane oxygenation (ECMO), a form of advanced life support that temporarily took over the work of his heart, giving it time to recover—or, if necessary, bridging him to a transplant.

Cedars-Sinai experts say Gilliam’s case illustrates the importance of bystander CPR and quick medical response.

“The key to G’bari surviving sudden cardiac arrest was the fast-acting individuals who provided CPR, facilitated the use of an AED, and the Cedars-Sinai Emergency Department and cardiothoracic surgery teams who began ECMO within the hospital,” said Evan Kransdorf, MD, PhD, assistant professor of Cardiology in the Smidt Heart Institute and one member of Gilliam’s team of physicians and surgeons.

During cardiac arrest, blood stops circulating, explained Pedro Catarino, MD, a cardiothoracic surgeon in the Smidt Heart Institute at Cedars-Sinai.

“The cells of the body, particularly the brain, will die within a few minutes without circulation,” Catarino said. “Gilliam’s heart was in and out of a rhythm that doesn’t sustain circulation, so the surgery team put him on emergency life support.”

Gilliam’s heart had ceased working, so he was listed in the organ donation system. After 12 days on life support, Gilliam received the news every transplant candidate hopes for: A donor heart had become available.

“Heart transplantation offers a new chance at life for patients like Gilliam,” Catarino said. “Gilliam is an athlete and can look forward to going back to his career with a heart that has a long lifespan.”

A pathology report showed Gilliam had a severe form of hypertrophic cardiomyopathy, an inherited condition that causes the heart muscle to thicken so that the heart cannot contract and pump blood properly. The condition likely caused Gilliam’s sudden cardiac arrest, his medical experts say.

“Many people with hypertrophic cardiomyopathy don’t have symptoms, and athletes who are used to pushing themselves to be out of breath might not realize they have it,” Kransdorf said.

Geneticists in the Smidt Heart Institute tested samples of Gilliam’s heart and found that he had a genetic variant associated with hypertrophic cardiomyopathy. Experts encourage anyone with a family history to be screened for the condition, which affects about 1 in 500 people. Gilliam’s close family members are undergoing genetic testing.

Gilliam, whose credits include performing with Bad Bunny and on Jimmy Kimmel Live!, is now in physical therapy and preparing to return to dance.

“With dancing, it feels like I'm able to be my most authentic self and be the most vulnerable version of myself. It makes me feel alive,” he said.

Prior to his medical emergency, Gilliam’s schedule consisted of dance classes and gym training five days a week. He hopes to return to intense days and to continue teaching dance to elementary school students and choreographing dancers on TV and film sets. His mother and girlfriend are supporting him, as are many friends, family members and fellow dancers.

“What I learned from this experience is everyone should be trained in CPR because you never know what's going to happen,” Gilliam said. “Even more so, be a person of service. If you have the opportunity to help someone, do it.”

Read more from Cedars-Sinai Stories and Insights—Sudden Cardiac Arrest: Genetic Cause More Common in Younger People

Younger people who experience sudden cardiac arrest are more likely to have a genetic cause than older people who experience it, according to new research from the

“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,” said Evan Kransdorf, MD, PhD, assistant professor of Cardiology in the Smidt Heart Institute and first author of the study. “For people who carry a variant linked to sudden cardiac arrest, a cardiologist can prescribe medications or lifestyle changes that can decrease the chances of experiencing this dangerous event.”

Sudden cardiac arrest, an electrical malfunction that causes the heart to beat very rapidly, is fatal in 90% of cases, according to the American Heart Association. The Cedars-Sinai Health Sciences University investigators found that 10% of people 29 and younger who have sudden cardiac arrest carry genetic variants linked with the condition.

The 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 the ongoing Oregon Sudden Unexpected Death Study and the Ventura Prediction of Sudden Death in Multi-Ethnic Communities study—both created by Sumeet Chugh, MD, director of the Center for Cardiac Arrest Prevention in the Smidt Heart Institute, to improve understanding of the condition.

Investigators performed whole genome sequencing, which maps a person’s entire genetic code. They identified 15 genes in which damaging genetic variants can occur and disrupt the gene’s function and increase risk of sudden cardiac arrest. They found the prevalence of damaging genetic variants decreased with age:

• 10% of people age 29 and younger harbored a damaging genetic variant.
• 7% of people age 30-49 harbored a damaging genetic variant.
• 4% of people age 50-69 harbored a damaging genetic variant.
• 3% of people age 70 and older harbored a damaging genetic variant.

In older people, sudden cardiac arrest is more likely to be caused by a narrowed or blocked heart blood vessel rather than a heart condition caused by a damaging genetic variant, according to the investigators.

The investigators said more research will help uncover other genes linked to sudden cardiac arrest.

“This study is more representative of the U.S. population than other studies because it includes data from two communities rather than data from people already being seen at a medical center,” said Chugh, who is also vice dean and chief artificial intelligence health research officer at Cedars-Sinai and senior author of the study.

Additional Cedars-Sinai authors include Marco Mathias, BS; Kotoka Nakamura, PhD; Harpriya Chugh, BE, MSHS; David Nguyen, BS; Paul D. Pharoah, MD, PhD; and Kyndaron Reinier, MPH, PhD.

Other authors include Jonathan Tyrer, PhD; Zeynep Akdemir, PhD; Eric Boerwinkle, PhD; and Bing Yu, PhD. 

Funding: The study was funded by The National Institute of Health, NHLBI Grants R01HL145675 and R01HL147358; NIH DHHS Contracts HHSN268201700001I, HHSN268201700002I, HHSN268201700003I, HHSN268201700004I, HHSN268201700005I.

Read more from Cedars-Sinai Stories and Insights: Heart Attack, Cardiac Arrest, Heart Failure—What’s the Difference?

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. 

Read more in Discoveries: 3D Cameras Could Help Diagnose Rare Genetic Diseases