Large-scale mass-sporting events pose unique challenges for emergency health teams. Data is limited in athletes with sudden cardiac arrests (SCAs) and the emergency medical services (EMS) in major sporting events that took place after the coronavirus pandemic.

This retrospective observational study describes data from the Taipei Marathon event that took place on December 19, 2021, in Taiwan. The temperature was about 15.2–19.3°C. Four SCAs among 18,144 half-marathoners and the EMS were enrolled.

A medical command center was set up 100 meters from the finish line. Ten medical tents, one first-aid station, and nine event ambulances were distributed along the course, and one medical tent was placed near the baggage storage area. Each medical tent comprised: 1 doctor, 1–3 nurses, and 1–3 paramedics. The in-event EMS also comprised a mobile first-aid team. Thirty paramedics rode motorcycles and carried automated external defibrillators and emergency medical kits throughout the racecourse.

Among the 7,811 full- and 18,144 half-marathoners, the total number of SCAs was four male half-marathoners. Three runners (75%) stated that they decreased their weekly running volume during the pandemic restrictions’ period. Two runners (50%) experienced cardiac arrest in the final quarter of the race. The median interval of time between SCA occurrence and EMS arrival was 2.5 minutes (interquartile range, 0.5–4 minutes). Electric shocks were delivered to all the four runners (100%) experiencing ventricular fibrillation, and all of them were successfully resuscitated in the field. The median interval of cardiopulmonary resuscitation duration before return of spontaneous circulation was 8.5 minutes (interquartile range, 6–9.5 minutes).

4/18144 is a significantly high number of SCA compared to data from the annual Taipei Half-Marathon between 2016 and 2020 and past half-marathons worldwide. The high prevalence rate of SCA (22 per 100,000) may be due to inadequate acclimation and training volumes.