Study Reveals 4 Warning Signs You May Experience Before Cardiac Arrest

Cardiac arrest is a major medical event in which the heart suddenly stops beating. It’s estimated to occur in roughly 356,000 Americans every year, according to the American Heart Association.

Most people who experience cardiac arrest outside of a hospital setting die, but immediate medical treatment can help keep people alive, according to the National Institutes of Health. So it’s crucial to be aware of the signs. And new research from the Smidt Heart Institute at Cedars-Sinai Health System in Los Angeles has zeroed in on the most common symptoms that happen in the 24 hours before cardiac arrest.

According to the study, which was published in Lancet Digital Health, at least one of a group of four symptoms — chest pain, shortness of breath, excessive sweating and seizure-like activity — was reported in half of study participants who had a cardiac arrest.

The researchers used data from 823 people who experienced cardiac arrest, and data from a control group of 1,171 people who reported symptoms but did not experience full arrest. For those who did undergo cardiac arrest, symptoms were reported by bystanders, emergency medical service workers, or the person experiencing the arrest themselves.

The most common warning signs varied by gender. Chest pain was most common in men, while shortness of breath was most common in women.

“I think it’s important to have this type of data, particularly related to sex differences in symptoms of cardiovascular disease because we know that men and women can have different symptoms,” said Dr. Anais Hausvater, a cardiologist at New York University Langone Heart who was not affiliated with the study. “However, I would say that a lot of the symptoms that they looked at are symptoms of many different cardiovascular diseases.”

Hausvater said she wouldn’t want this study’s findings to discount any early signs of cardiac arrest or cardiovascular disease as a whole. According to the Centers for Disease Control and Prevention, additional symptoms of heart disease can include fatigue, dizziness, palpitations and general chest discomfort.

“I think there is nothing that this study could have found that would change my recommendation of who should be going to an emergency room when they have cardiac-sounding symptoms,” Hausvater said.

“I worry about the messaging related to this study, because there’s kind of [a] suggestion that they wanted to compare different EMS calls, and potentially findings of this study could help decide which EMS calls are more important than others,” she said. “But I worry that the implication could be that people who are having cardiac symptoms might be delayed.”

Symptoms relayed over a 911 phone call aren’t enough to determine whether someone is sick, Hausvater said.

“Certainly, it can help, but I think I would take some of these findings with caution because it doesn’t necessarily change what I would do in my practice,” she said.

So, no matter what heart disease symptoms you have ― even if they’re not one of the common four listed in the study ― you should address them. Issues like chest pain, dizziness, irregular heartbeat and extreme fatigue should also never be ignored.

Dr. Joseph Marine, vice director of operations for the division of cardiology and section chief of cardiology for Johns Hopkins Community Physicians in Baltimore, pointed out that it’s a challenging scientific task to identify the symptoms before cardiac arrest.

“I think it’s a very interesting thought-provoking study … and although there are some limitations to the methods, this group really did it as well as it can be done,” Marine said.

One limitation, Marine pointed out, is that the study only used data from the 823 patients whose cardiac arrests were “witnessed by a bystander or EMS personnel,” according to the study’s authors. In all, there were more than 1,600 out-of-hospital cardiac arrests during the study period.

This means we don’t know what initial symptoms the people not examined in the study experienced, Marine said. Additionally, while symptoms were reported by emergency workers, bystanders or the patients themselves, Marine said there is room for error and misremembering.

The timing of the study is a potential limitation, too, Hausvater said. The study compared the two groups of people mentioned above, but the cardiac arrest group was followed through the pandemic years and the control group was not.

“Basically, the cardiac arrest patient spans the COVID pandemic, where we know there were more cardiac arrests, and the symptoms might have been slightly different because some of those cardiac arrests might have been related to COVID infection,” Hausvater said.

The biggest risk factors for cardiac arrest, and what to do

“Risk factors for [heart attack] and cardiac arrest include older age, diabetes, high blood pressure, high cholesterol, heart failure and other forms of heart disease,” Marine said.

Hausvater noted that people with a history of heart attacks may be at higher risk as well.

In younger people, the risk factors include ion channel abnormalities and genetic abnormalities, “which can lead to abnormal heart muscle development,” Marine explained. “But in older adults, ventricular arrhythmia [abnormal heartbeats in the lower chambers of your heart], either due to a blocked coronary artery or due to serious heart muscle disease or heart failure, is the most common cause.”

Heart disease is common and deadly, but certain life choices can lower your risk of cardiac arrest and other forms of cardiovascular disease.

According to Marine, “the number one thing is taking good care of yourself [by] eating a healthy diet, maintaining a healthy weight, getting regular exercise, avoiding drugs and alcohol, getting good sleep.”

“We recommend a Mediterranean-style diet, and if you have hypertension or high blood pressure, we recommend a low-salt diet,” Hausvater said.

Additionally, it’s important to go to the doctor for regular checkups, which can help you determine and control any of the modifiable risk factors, like high blood pressure and high cholesterol, Marine said.

Learning CPR can be lifesaving, too.

“Sudden cardiac arrest basically refers to some sort of illness in which the heart stops, and a patient becomes pulseless,” Hausvater said. “And the treatment is immediate CPR.”

For example, NFL player Damar Hamlin, who suffered cardiac arrest during a football game last year, received immediate medical attention and has since returned to the field.

“It would be great if that were the norm, rather than the exception,” Marine said.

Marine said everyone should take a Red Cross or American Heart Association CPR course. “The point to make [is] that besides taking care of yourself, everybody should learn CPR and how to use an automated external defibrillator,” he said.

Cardiac arrest is relatively common, making it important to know this lifesaving skill.

“The medical literature is very clear that those who suffer a cardiac arrest, if CPR is applied early, they have a much higher likelihood of survival,” Marine said.

And if you notice any concerning issues, get to a doctor as soon as possible. Whether you notice one of the four symptoms mentioned above or any other signs of a cardiovascular issue, you should bring it to the attention of a health professional, Hausvater emphasized.

“If you feel unwell, and you feel as though something is wrong, you should seek medical attention,” she said.