The incidence of young athletes experiencing sudden cardiac arrest during competitive sporting events is slim—just 0.76 cases in 100,000 athlete-years—but it does happen, according to one team of Canadian researchers who analyzed dozens of out-of-hospital cardiac arrests in an effort to dissect the underlying causes of these tragedies.
Just 43.8 percent of competitive athletes between 12 and 45 years old survive to discharge after being hospitalized for sudden cardiac arrest, corresponding author Paul Dorian, MD, and colleagues wrote in their five-year study, which was recently published in the New England Journal of Medicine. The reported incidence of sudden cardiac death in young patients under 35 years old has in past research ranged from 1 to 6.4 cases per 100,000 patient-years, Dorian et al. wrote, and any individual who is predisposed to heart problems sees a markedly higher risk of cardiac arrest during high-intensity activities.
“The occurrence of sudden cardiac arrest in young persons during participation in competitive sports is a rare but tragic event,” Dorian and co-authors wrote. “In numerous jurisdictions, preparticipation screening systems have been implemented on the assumption that most cases of sudden cardiac arrest that occur during sports activities can be predicted and prevented by identifying persons at risk, withdrawing them from competitive sports and, in selected cases, applying therapeutic preventive measures.”
While these preparticipation screening programs ideally identify at-risk athletes, Dorian and his team said the efficacy of such programs remains controversial.
The researchers pulled records of all cardiac arrests attended by paramedics during a five-year period in Ontario, Canada, using the Rescu Epistry cardiac arrest database. Information for each of these cases—whether they resulted from a direct heart complication or had nothing to do with a cardiac cause—was drawn from ambulance call reports, autopsy reports, in-hospital data and records of direct interviews with patients or family members.
Dorian and colleagues found 74 cases of sudden cardiac arrest in athletes throughout the course of 18.5 million person-years of observation. Sixteen of these cases occurred during competitive sports, while 58 took place in noncompetitive settings. Though noncompetitive athletes saw higher rates of cardiac arrest, the eventual incidence rate for competitive events was 0.76 cases of sudden cardiac arrest per 100,000 athlete-years, and the researchers found that, among competitive athletes, two deaths were attributed to hypertrophic cardiomyopathy. None were attributed to arrhythmogenic right ventricular cardiomyopathy.
Competitive sports that saw the highest numbers of cardiac arrest were racing events, soccer, basketball, ice hockey, Jujitsu, baseball and rugby, Dorian et al. wrote.
In all, sudden cardiac arrest due to structural heart disease was uncommon in competitive athletes. Noncompetitive sports, though, saw higher rates. In noncompetitive athletes, accidents at the gym or during running exercises saw the highest likelihood of cardiac arrest.
According to the study, three cases of cardiac arrest might have been more accurately identified had the athletes undergone preparticipation screening.
“The rarity of sudden cardiac arrest due to structural heart disease that we found in our analysis raises questions about the potential value of preparticipation screening,” the authors wrote. “Structural heart disease, such as hypertrophic cardiomyopathy, is more likely to be detected by electrocardiography than other causes of sudden cardiac arrest and is frequently cited as a reason for undertaking preparticipation screening."