title: Exercise-related sudden cardiac arrest in London: incidence, survival and bystander response.
abstract: The study aimed to (1) establish the incidence of exercise-related sudden cardiac arrest (SCA) in London, (2) investigate survival from exercise-related SCA and (3) examine factors related to survival.
  
  
  
  This retrospective observational study examined 2 years' data from the London Ambulance Service (LAS) cardiac arrest registry for patients in whom resuscitation was attempted following an out-of-hospital cardiac arrest (OHCA), a cardiac cause was presumed and the arrest occurred during or within 1 h of exercise.
  
  
  
  The incidence of exercise-related SCA in London was estimated to be 0.6 per 100 000 person-years which equated to 0.5% of all OHCA, and 1.5% of all OHCA with presumed cardiac aetiology and resuscitation attempted. The majority of cases were male and the incidence increased from age 40 years. Just under one-third of patients survived to hospital discharge. Survival in the Utstein comparator group (cases with presumed cardiac aetiology, resuscitation attempted, bystander witnessed and a presenting cardiac rhythm of ventricular fibrillation or tachycardia) was higher at 42%. Survival was significantly associated with initial cardiac rhythm (χ(2)=17.5, df=2, p<0.001) and bystander defibrillation (Fisher's exact test, p<0.05).
  
  
  
  Incidence of exercise-related SCA in the general population in London is rare. Survival following exercise-related SCA was considerably higher than survival for all OHCA with presumed cardiac aetiology and resuscitation attempted attended by the LAS during the same period. The major limitation of the study is the likely under identification of cases of exercise-related SCA.
authors.affiliation: Clinical Audit & Research Unit , London Ambulance Service NHS Trust , London , UK.
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Edwards
authors.affiliation: Clinical Audit & Research Unit , London Ambulance Service NHS Trust , London , UK.
authors.forename: Rachael T
authors.initials: RT
authors.lastname: Fothergill