A young, college basketball player was rumored to be a potential top pick in the professional basketball draft. Yet during a game midseason, he experienced arrhythmias (irregular rhythms of the heart's beating). He was removed immediately from the game and was treated. Three months later, during a tournament game, he collapsed and died. The cause of death? Sudden cardiac arrest. Other athletes, professionals and amateurs, have taken to the field only to meet a fatal defeat. Statistics show that this condition is rare, but what is sudden cardiac arrest? And why has it taken the lives of such strong, healthy athletes?

What Is Sudden Cardiac Arrest?

Sudden cardiac arrest in its simplest terms means an abrupt cessation of the blood flow.

"It's the abrupt loss of the heart's ability to pump blood," says Robert J. Myerburg, MD, director of the division of cardiology and a professor of medicine and physiology at the University of Miami in Florida.

Although there is usually no forewarning of a problem, symptoms can be missed or ignored, says John C. McMahon, PhD, a cardiovascular physiologist at the University of Texas in Houston. Symptoms might include fainting spells, chest pain, or shortness of breath.

Sudden cardiac arrest is not synonymous with a heart attack, Myerburg says. In a heart attack, the loss of blood supply causes heart muscle tissue to die. With sudden cardiac arrest, however, the body's electrical system becomes defective and the heart is not able to form an organized beat and is plunged into rapid or chaotic activity.

What Causes Sudden Cardiac Arrest?

Sudden cardiac arrest has often been blamed on cardiovascular disorders that are inherited or acquired. Moss says the most common cause is hypertrophic cardiomyopathy (HCM). HCM is an inherited condition which causes the heart's main pumping chamber, the left ventricle, to be abnormally thick. Other data supports his statement.

In 1996, one of the largest studies of sudden cardiac arrest appeared in the Journal of the American Medical Association (JAMA). In the study, researchers examined 158 sudden deaths that had occurred in trained athletes throughout the United States between 1985 and 1995.

More than half of the athletes competed at the high school level, 22% competed at the collegiate level, and seven percent were professional athletes. Basketball and football accounted for the largest percentage of sports. Other sports included track, soccer, baseball, swimming, volleyball, ice hockey, boxing, crew, ice skating, tennis, and wrestling.

Of those 158 athletes, 134 suffered from cardiovascular causes of sudden death. The most common cause was HCM. Other causes of sudden cardiac death in this study included coronary artery abnormalities and myocarditis, an inflammation of the heart muscle.

Researchers reported that about 90% of the athletes collapsed during or immediately after a training session, indicating that physical exertion appeared to trigger sudden death. In a 1993 commentary in the New England Journal of Medicine , Barry J. Maron, MD, of the Minneapolis Heart Institute Foundation and one of the study's authors, writes, "[Y]oung athletes with cardiovascular disease...may die suddenly during or immediately after vigorous exercise."

Medications and drugs may also cause abnormal heart rhythms which can trigger sudden cardiac arrest, says Arthur Moss, MD, professor of medicine (cardiology) at the University of Rochester Medical Center in Rochester, NY.

Small Risk

Fortunately, sudden cardiac arrest in young, fit athletes is rare.

"Only a small percentage of sudden death cases occurs in what appears to be overly healthy people who don't have any evidence of heart problems," says Moss. People under 20, he says, have a one in 100,000 chance of experiencing sudden cardiac arrest each year.

Can Anything Be Done to Prevent Sudden Cardiac Arrest?

In fact, results of a study of cardiovascular death in Italy suggests screening may help. A law in Italy in 1982 required athletes to be routinely screened to determine their risk for sudden cardiac arrest. A study reviewed the number of deaths before and after screenings of athletes with exam and ECG were required. They found a reduced rate of cardiovascular death when screening when initiated. And in Japan, all children get an electrocardiogram (EKG), a graphic record of the heart's electrical impulses, when they enter grade school and then are retested before high school.

The European Society of Cardiology released a 2005 recommendation that all young athletes receive an EKG as part of their pre-participation clearance. A study published in 2010 also notes that adding EKG to preparticipation screening can significantly increase detection of heart abnormalities in college athletes. In contrast, the 2007 recommendations of the American Heart Association, emphasize a series of screening questions and the physical examination. There are no currently recommended electrophysiological measures in the United States to detect individuals at risk.

While some medical professionals aim to include EKGs as part of a young athlete's physical examination, not everybody agrees. McMahon says an EKG isn't a cost-effective or an appropriate procedure. Even researchers in the JAMA article conclude that "pre-participation screening appeared to be of limited value in identification of underlying cardiovascular abnormalities."

At the very least, Moss says, schools, colleges, and professional teams should have personnel trained in CPR and a portable defibrillator nearby in case an arrest strikes. In addition, all athletes should at least receive pre-participation exams based on current best recommendations such as those of the American Heart Association.