Sudden cardiac arrest cases during the Standard Chartered Singapore Marathon 2023

Dear Sir, Sudden cardiac arrest (SCA) is a rare but catastrophic event in mass sporting events, with an estimated incidence of 1 per 31,000–55,000 runners.[1] There is scant literature on SCA during mass sporting events, especially in Asia. We report two cases of SCA that occurred during the Standard Chartered Singapore Marathon (SCSM) 2023, one of the largest marathons globally, with 44,000 participants from 70 countries. A list of all cases of SCA was obtained from the event medical team. Both cases were middle-aged Asian males with no known comorbidities [Table 1], who collapsed at approximately the 20-kilometre mark. Both runners received immediate bystander cardiopulmonary resuscitation (CPR) by fellow race participants and event medical staff, along with defibrillation using event-deployed automated external defibrillators (AEDs). Both achieved return of spontaneous circulation on scene after approximately ten minutes. They were evacuated to tertiary hospitals, where emergent coronary angiography revealed significant coronary artery disease. Both patients underwent percutaneous coronary intervention (PCI) with drug-eluting stents. They were discharged with good neurological function within 2–4 days.Table 1: Clinical characteristics of the two cases of out-of-hospital cardiac arrest during the Standard Chartered Singapore Marathon 2023.The SCA incidence rate from this single SCSM 2023 event (4.5 per 100,000 runners) was higher than the aggregated rate reported from a series of US marathons (1.01 per 100,000).[2] The possible contributing factors include heat stress,[3] a high proportion of recreational runners and inadequate acclimatisation of international participants. These cases highlight the importance of an optimised Chain of Survival (early recognition, bystander CPR, defibrillation, advanced life support and post-resuscitation care) in ensuring positive outcomes in SCA. The integrated response by the bystanders, Emergency Medical Services and acute hospitals played an instrumental role in these patients’ good outcomes. These findings have three major implications: Expand bystander CPR training and AED accessibility. Bystander intervention is the strongest predictor of survival in SCA.[4] Implement emergency action plans for mass sporting events. Medical coverage should ensure rapid AED access (within 3 minutes of collapse) and mobile medical responders along the race route.[5] Evidence-based guidelines are needed to guide optimal resource deployment. Personalise pre-participation screening. Currently, pre-participation screening is not mandated by the SCSM. While routine electrocardiogram screening is debated,[6] targeted assessment or screening for high-risk individuals, including those with cardiovascular symptoms or sedentary lifestyles, may be beneficial. Despite the low absolute risk of SCA, exercise remains highly protective for overall cardiovascular health. Although SCA is often fatal, these two cases demonstrate that good clinical outcomes can be achieved when an optimised Chain of Survival is implemented. Well-coordinated emergency response systems allow mass sporting events to remain safe while maximising public health benefits. Bridging knowledge gaps on SCA during sporting events can inform the design of programmes and policies to prevent and treat SCA in this setting. Financial support and sponsorship Nil. Conflicts of interest HO AFW is a member of the SMJ Editorial Board and was thus not involved in the peer review and publication decisions of this article.