From Pages to Practice
Sudden cardiac arrest (SCA) in young athletes during participation in competitive sports is rare but devastating. One recognized cause of such events is hypertrophic cardiomyopathy (HCM), a genetic disorder characterized by pathologic thickening of the walls of the heart. In 2015, the National Collegiate Athletic Association (NCAA) announced a plan to recommend preparticipation EKG for all collegiate basketball players to screen for disorders such as HCM, but the proposal was later retracted following wide opposition from the sports medical community. At the heart of this issue were uncertainties about the incidence of SCA in young people and the effectiveness of early screening strategies to detect high-risk features for SCA.
In this week’s issue of NEJM, Landry and colleagues examined the incidence and underlying causes of SCA in young persons during both competitive and noncompetitive sports in Ontario, Canada. Prior studies that evaluated sudden cardiac deaths used autopsy reports and death certificates. The novelty of this study lies in the use of a prospective population-based database (Rescu Epistry) of out-of-hospital cardiac arrests attended by emergency medical services in a region with more than 6.6 million people. This innovative approach allowed the authors to include a key population missing from previous reports, namely those who had been successfully resuscitated from SCA.
The investigators identified all out-of-hospital cardiac arrests (both deaths and resuscitations) from 2009 through 2014 in individuals aged 12 to 45 years, and determined the underlying causes of SCA by correlating information in the database with hospital and autopsy data. During an estimated 18.5 million patient-years of follow up, 3825 out-of-hospital SCAs were identified, of which 2144 (56.0%) occurred in a public space such as a recreational facility or stadium. Only 74 events occurred during a sport or within an hour after exertion of more than 3 metabolic equivalents. Of the 74 sports-related SCAs, 16 occurred during competitive events (formally sanctioned by an officially recognized sports organization, such as race events or soccer), and 58 occurred during noncompetitive sports (mostly during gym workouts and running).
The incidence of SCA during competitive sports was 0.76 per 100,000 athlete-years. The rate of survival after SCA was comparable between competitive athletes (43.8%) and noncompetitive athletes (44.8%). Of the 16 cases of SCA among competitive athletes, two were attributable to HCM and none to arrhythmogenic right ventricular cardiomyopathy (ARVC). The authors estimate that preparticipation screening would have identified no more than three competitive athletes to be at risk of SCA in this patient population, indicating that at least 146,000 athletes would have had to be screened to identify one person who had SCA during competitive sports.
The authors acknowledge that the study might underestimate the rate of SCA because all competitive athletes might not have been identified. Further, although the study captures both athletes who did and did not survive SCA, at-risk athletes who had been deterred from playing sports following health screenings might have not been included. Nonetheless, the study highlights the rare incidence of SCA among athletes, as well as the low incidence of structural or arrhythmogenic causes of SCA that could have been identified during preparticipation screening. The finding from this large study calls into question the utility and cost-effectiveness of performing cardiac screening to prevent SCA in young athletes.