The Heart of the Matter

Sudden Cardiac Arrest in Young Athletes and Those Working to Prevent It

Todd Rudo, M.D. – Chief Medical Officer at Clario

LeBron James is widely regarded as one of the greatest professional basketball players in the sport’s history. This summer, his 18-year-old son Bronny James suffered a cardiac arrest during a college basketball team practice and was quickly resuscitated and rushed to the hospital. Fortunately, the news from there has all been positive. He was released back home after several days and reportedly has recovered quite well. Although details are limited, it was recently revealed that he was diagnosed with a congenital heart defect. 

But what actually happened, and what can be done to prevent this? 

I write this blog now not just to share some background on sudden cardiac arrest in athletes but also because I want to highlight Clario’s involvement with Simon’s Heart, an organization dedicated to preventing sudden cardiac arrest in children and young adults. One of the core initiatives of Simon’s Heart is providing free heart screenings to students in an effort to detect cardiac abnormalities and prevent tragedy. 

Clario has donated decommissioned ECG machines to Simon’s Heart for nearly ten years to enable these screenings.  The organization has screened the hearts of almost 20,000 students since its inception, with more than 10,000 of those on Clario machines. Through these efforts, they have been able to diagnose previously undetected heart conditions in almost 150 students! 

Back to Bronny James though – how common is this? Every year, about 2,000 people in the United States under the age of 25 die from sudden cardiac arrest. For context, car accidents kill about 11,000 each year in this same age group. The frequency of sudden cardiac death may not be very high, but the consequences are devastating, especially considering that in most cases, those deaths were preventable.

The most common cause of sudden cardiac arrest in young athletes is a condition called hypertrophic cardiomyopathy (HCM). HCM, which is an inherited genetic disease, is a result of the heart muscle growing excessively thick with disorganized muscle cells, causing it to function inappropriately. In some cases, the first symptom of HCM is a lethal heart rhythm, called ventricular tachycardia (VT). Without interventions such as CPR, life-saving medications, and a defibrillator shock, VT is a fatal rhythm. Screening with history and physical exam, ECG, and if appropriate an echocardiogram, can aid in detecting this condition. There are many other types of inherited, structural heart abnormalities that can also lead to VT and sudden death, but HCM is the most common. 

A slightly less common cause of cardiac arrest in athletes is myocarditis. In this condition, the heart muscle becomes inflamed, usually following a viral infection, but sometimes can result from an underlying immune system disorder. Famously, college basketball player Hank Gathers, Loyola Marymount University’s leading scorer and a candidate for the player of the year in the 1988-1989 season, suffered sudden cardiac arrest and died, his autopsy revealing evidence for myocarditis. Similar to HCM, often the symptoms of this are either absent, very limited, or quite vague, but with ECG, blood work, and imaging tests, it is generally detectable and manageable.

And of course, many of us remember the recent collapse of professional football player Damar Hamlin last season, an apparent case of commotio cordis. This is an exceptionally rare condition in which a blow to the chest can cause a sudden change in heart rhythm called ventricular fibrillation. With quick reaction on the field that day his life was saved, a tribute to the preparedness of the trainers and field medical staff, ready to respond urgently. 

Simon Sudman suffered from a different condition though. He was a seemingly healthy three-month-old baby boy who sadly died one night in his sleep. After his parents were encouraged by their pediatrician to get their own hearts checked, Phyllis, Simon’s mom, discovered a heart condition called Long QT Syndrome (LQTS). LQTS has been linked to up to 15% of sudden infant deaths (SIDS). Like the others, this is yet another condition that is largely without any symptoms, and only with proper screening can a diagnosis be made. Long QT syndrome can cause cardiac arrest at any age, not just in children. 

At Clario, most of the work our Cardiac Safety group focuses on is the detection of drug-induced QT prolongation. While some people have an inherited abnormality with the QT interval (as Simon did), certain medications can also directly cause the same condition to develop. If taken in high enough doses, those medications can also cause sudden death. Importantly, with proper screening during a clinical trial and high-quality ECG data, this is detectable and preventable. If a medicine is determined to prolong the QT interval, physicians can be warned of this risk and monitor patients more closely during treatment. 

Screening young children and athletes for cardiac disease is sometimes a controversial topic. There is an argument that the cost of ECG screening, and the risk of false positives leading to unnecessary additional testing, outweigh the benefits of screening for such rare conditions. Some argue that only children with risk factors (such as family history) or concerning symptoms (such as fainting episodes, exertional chest pain, and heart palpitations) require an ECG or echocardiogram. Founded by Simon’s parents, Darren and Phyllis Sudman, the vision of Simon’s Heart is a future in which parents and communities don’t lose children to detectable and treatable heart conditions. They pursue this vision through free heart screenings for students, placing AEDs where children learn and play, providing CPR Education, and through Advocacy. Until public policy changes and makes screening routine, Clario will continue to support this important cause, and do our part to make a difference.