On a Monday night in early January 2023, the Buffalo Bills were in Cincinnati to take on the hometown Bengals. The game was a highly anticipated, prime time matchup between two of the best teams in the National Football League, but it would be interrupted and ultimately postponed after Bills safety Damar Hamlin suffered a frightening injury during the game. After tackling Bengals wide receiver Tee Higgins, Hamlin stood up, only to fall flat moments later. Medical personnel rushed to Hamlin’s side, and it was later determined he went into cardiac arrest. Days went by as football fans across the nation prayed for Hamlin’s recovery. Good news arrived by the end of the week, as doctors treating Hamlin reported his condition showed marked improvement. Indeed, within days of that news, Hamlin was on his way back to Buffalo, much to the delight of millions of people across the country. Hamlin’s story made international headlines and left many people across the globe asking questions about cardiac arrest.

What is cardiac arrest?

The National Heart, Lung, and Blood Institute reports that cardiac arrest occurs when the heart suddenly and unexpectedly stops pumping. One of the dangers of cardiac arrest is that blood stops pumping to the brain and other vital organs. In the days after doctors first shared news regarding Hamlin’s recovery, praise was heaped on the medical personnel, including Bills assistant athletic trainer Denny Kellington, for their rapid response, which saved Hamlin’s life and helped preserve the 24-year-old safety’s neurological function. How dangerous is cardiac arrest? The NHLBI notes that cardiac arrest is a medical emergency. In fact, the NHLBI indicates that nine out of 10 people who have cardiac arrest outside of a hospital die. That makes the recovery of Hamlin, who was administered CPR on the field for several minutes prior to being transported to the hospital, all the more incredible.

What are the symptoms of cardiac arrest?

Johns Hopkins Medicine notes that there are no symptoms in some cases of cardiac arrest. However, individuals may experience these symptoms prior to cardiac arrest:

• Fatigue

• Dizziness

• Shortness of breath

• Nausea

• Chest pain

• Heart palpitations

• Loss of consciousness

What causes cardiac arrest?

The suddenness of the injury to Hamlin undoubtedly left millions of people confused about how the condition could affect a young professional athlete seemingly in peak physical condition. Specifics about Hamlin’s medical history are protected by privacy laws, so unless Hamlin chooses to share that information, the public will not learn about why he suffered from cardiac arrest. However, Johns Hopkins reports that there are three main causes of the condition.

• Arrhythmia and ventricular fibrillation: Arrhythmia is a condition marked by problematic electrical signals in the heart that lead to an abnormal heartbeat. Ventricular fibrillation is a type of arrhythmia that causes the heart to tremble rather than pump blood normally. It is the most common cause of cardiac arrest.

• Cardiomyopathy: Cardiomyopathy is a condition in which the heart is enlarged. Johns Hopkins notes that when a person has cardiomyopathy, the heart muscle thickens or dilates, which causes abnormal contractions of the heart.

• Coronary artery disease: The NHLBI indicates that most people who experience cardiac arrest have heart disease, even if they didn’t know it beforehand. The most common type of heart disease is coronary artery dis-ease, which is marked by the buildup of cholesterol inside the lining of the coronary arteries. That buildup leads to the formation of plaque which can partially or completely block blood flow in the arteries of the heart. Certain behaviors or lifestyle choices also can trigger cardiac arrest. For example, the NHLBI reports that heavy alcohol consumption or re-cent use of cocaine, amphetamines or marijuana can cause cardiac arrest. Severe emotional stress and physical exertion, including that which is typically required of competitive athletes, also can trigger cardiac arrest. The Damar Hamlin incident thankfully appears to have had a happy ending. But millions more people could be vulnerable to cardiac arrest. More information is available at nhlbi.nih.gov.