LOS ANGELES, July 18: Two studies from investigators at Cedars-Sinai Health Sciences University move the medical field closer to solving a longstanding challenge: predicting who is at risk for sudden cardiac arrest.
“The majority of people who have a sudden cardiac arrest outside of a hospital will die, so the best protection is being aware of risk,” said Kyndaron Reinier, PhD, MPH, associate director of Epidemiology in the Center for Cardiac Arrest Prevention in the Smidt Heart Institute at Cedars-Sinai and an author of both studies.
Sudden cardiac arrest happens when a problem with the heart’s electrical system causes the heart to stop beating. It is different from a heart attack, which is caused by a lack of blood flow to the heart. More than 350,000 people experience sudden cardiac arrest outside of a hospital in the U.S. each year, and only about 10% survive.
Experts know that people with low left ventricular ejection fraction, when the heart’s main pumping chamber is weak and pumps less than it should, are at higher risk for sudden cardiac arrest. But this marker has become less effective and other indicators are needed to capture more people at risk.
“More than two-thirds of people who have cardiac arrest don’t have low left ventricular ejection fraction, so using this marker alone misses too many people,” Reinier said.
A study published in the journal Circulation: Arrhythmia and Electrophysiology reports that warning symptoms combined with clinical history could predict imminent sudden cardiac arrest. A second study, published in the Journal of the American Heart Association , reports that having more than one cardiac event over time could signal rising risk.
Reading Warning Symptoms
In the Circulation: Arrhythmia and Electrophysiology study, investigators used machine learning to identify combinations of symptoms and medical history that best predicted sudden cardiac arrest in the near future.
The study included people enrolled in two separate, longstanding studies in Oregon and Ventura County, California, that were founded by Sumeet Chugh, MD, director of the Center for Cardiac Arrest Prevention in the Smidt Heart Institute. The investigators compared 364 people who called 911 when experiencing symptoms such as chest pain and survived sudden cardiac arrest, with 313 people who called 911 for similar symptoms but did not experience sudden cardiac arrest.
The analysis found that people with sudden cardiac arrest were more likely to have a combination of shortness of breath and diagnosed coronary artery disease or heart failure than people who did not experience sudden cardiac arrest. Seizure-like symptoms without chest pain or shortness of breath were also more common in people who experienced sudden cardiac arrest.
The investigators also found that chest pain combined with coronary artery disease predicted imminent arrest in women, while chest pain combined with heart failure predicted it in men.
Warning symptoms most often occurred at least 15 minutes prior to the sudden cardiac arrest, a time frame that would make it possible to call 911. In earlier research, the investigators found that 81% of people delayed their 911 call, reducing their chances of successful revival by ambulance paramedics.
These findings could be used to create risk-predicting algorithms for use by urgent care and emergency medicine providers, the investigators said. “While more research is needed, such risk prediction algorithms have the potential to avoid 911 call delays following warning symptoms of sudden cardiac arrest,” said Chugh, vice dean and chief AI health research officer at Cedars-Sinai.
Tracking Risk Over Time
The JAHA study was carried out in the Observational Study of Cardiac Arrest Risk cohort at Cedars-Sinai, established by Chugh, that has been tracking the health of approximately 400,000 residents of Los Angeles County from 2017 onward. Of these, the investigators followed more than 6,700 people hospitalized at Cedars-Sinai for heart failure and more than 2,900 people hospitalized in the health system for acute coronary syndrome, when an artery blockage reduces blood flow to the heart.
Investigators found that patients in both groups who experienced a recurrent cardiovascular event faced a higher risk of sudden cardiac arrest.
Patients who had a second coronary artery blockage were more than three times as likely to experience sudden cardiac arrest as those without a recurrence. Patients who were hospitalized a second time for heart failure were nearly twice as likely to experience sudden cardiac arrest. Risk climbed with each additional heart failure hospitalization. The investigators compared the findings to what was found in participants of the Framingham Heart Study, which enrolled participants about 50 years earlier. The results were similar, however the heart failure result in that study did not reach statistical significance.
Reinier said that physicians should consider sudden cardiac arrest as being more likely when a patient is hospitalized for a heart issue a second time.
“This may mean running additional tests,” Reinier said. “It may mean educating the patient about what cardiac arrest is and the importance of having a family member who knows to call 911 and start CPR immediately if their loved one collapses.”
Moving Beyond Dead Ends
Chugh, senior author of both studies, said the combined findings point toward a more flexible approach to prediction.
“Near-term and long-term predictions are parallel approaches that can help us move past roadblocks we face in preventing death from this lethal heart event,” Chugh said.
Additional research, including studies in different populations, are needed to confirm whether the factors the investigators studied could be used in prediction tools, study authors said.
Cedars-Sinai investigators continue to study predictors of sudden cardiac arrest, and their work includes using AI to study patterns in heart tests called electrocardiograms and looking for genetic causes.
Additional Cedars-Sinai authors in the Circulation: Arrhythmia and Electrophysiologystudy include Harpriya Chugh, BS; Vishnu Kadiyala, MD; Arayik Sargsyan, MPH; Audrey Uy-Evanado, MD; Kotoka Nakamura, PhD; Elizabeth Heckard, MS; Marco Mathias, BS.
Other authors include Tristan Grogan, MS; David Elashoff, PhD; Angelo Salvucci, MD; and Jonathan Jui, MD, MPH.
Funding: Dr. Chugh was funded by the National Heart Lung and Blood Institute, National Institutes of Health.
Additional Cedars-Sinai authors in the Journal of the American Heart Association study include Marita Knudsen Pope, MD, PhD; Harpriya Chugh, BS, MSHS; Thien Tan Tri Tai Truyen, MD; Marco Mathias, BS; and Audrey Uy-Evanado, MD.
Other authors include Honghuang Lin, PhD; Dan Atar, MD, Nichole Bosson, MD, MPH, and Emelia J. Benjamin, MD, ScM
Funding: The Framingham Heart Study is funded by the National Heart, Lung, and Blood Institute, National Institutes of Health. Dr. Benjamin is partially funded by The National Heart, Lung, and Blood Institute, National Institutes of Health.
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