Recent data from the Race Associated Cardiac Event Registry (RACER) reveals that while the incidence of sudden cardiac arrest (SCA) during marathons and half-marathons in the U.S. has remained relatively stable over the past two decades, the risk of sudden cardiac death (SCD) has significantly decreased by nearly 50%. The study, which analyzed data from over 29 million participants between 2010 and 2023, was presented at the American College of Cardiology Scientific Session and published in *JAMA*.
Jonathan H. Kim, MD, associate professor of medicine and director of Emory Sports Cardiology, emphasized that despite a slight uptick in the incidence of sudden cardiac arrest since 2020, the risk of death has sharply declined. He attributed this improvement to advancements in emergency response protocols, including faster access to automated external defibrillators (AEDs) and quicker deployment on racecourses, along with increased use of bystander CPR.
The study, which compared the data with that from RACER 1 (2000-2009), found that the incidence rate of sudden cardiac arrest remained relatively unchanged at 0.6 per 100,000 participants from 2010-2023, compared to 0.54 per 100,000 from 2000-2009. The study also highlighted a notable reduction in SCD, from 0.39 per 100,000 in 2000-2009 to 0.2 per 100,000 in 2010-2023, with the number of deaths falling from 71% of cardiac arrests to just 34%.
The study revealed that SCA was more common in male participants (1.12 per 100,000) and marathons (1.04 per 100,000), compared to women (0.19 per 100,000) and half-marathons (0.47 per 100,000). Notably, the incidence of sudden cardiac arrest among male marathon runners rose after 2020, from 1.43 per 100,000 (2010-2019) to 2.79 per 100,000 (2020-2023), though the reasons for this increase are unclear.
Among the 128 participants with detailed information, those who survived sudden cardiac arrest were generally older (47.6 years) compared to those who died (34.4 years). Hypertrophic cardiomyopathy (HCM) was no longer the most common cause of cardiac arrest; instead, coronary artery disease (CAD) became the leading cause, found in 40% of cases.
The study also highlighted improvements in emergency response: bystander CPR was administered in all cases of SCA between 2010-2023, and AEDs were used almost universally. These interventions, particularly the presence of a shockable rhythm, were critical factors in survival outcomes.
While participation in long-distance races continues to grow, Kim emphasized the importance of primary prevention strategies for high-risk groups, particularly male marathoners, to further reduce the incidence of sudden cardiac arrest in the future.