AbstractObjectiveTo determine the effect of electrocardiogram (ECG) screening on prevention of sudden cardiac arrest and death (SCA/D) in young athletes and military members.Data SourcesMEDLINE, Embase, Cochrane CENTRAL, Web of Science, BIOSIS, Scopus, SPORT discus, PEDro, and clinicaltrials.gov were searched from inception to dates between 2/21/19 and 7/29/19.Study SelectionRandomized and non-randomized controlled trials, where pre-participation examination including ECG was the primary intervention used to screen athletes or military 40 years of age or younger. Accepted controls were no screening, usual care, or pre-participation examination without ECG. 3 published studies, and one conference abstract were identified for inclusion.Data ExtractionIn all four studies, risk of bias was assessed with the Cochrane risk of bias tool, and found to be generally high. Two studies had data extracted for random effects meta-analysis, and the remaining study and conference abstract were included in narrative review.Data Synthesis4 studies (11,689,172 participants) were included, all at high risk of bias. Pooled data from two studies (n= 3,869,274; very low quality) showed a 42% relative decrease in sudden cardiac death, equating to an absolute risk reduction of .0016%. Uncertainty was high, with a potential 67% relative decrease to a 45% relative increase in those screened with ECG based on 95% confidence intervals (RR 0.58; 95%CI 0.23, 1.45). Heterogeneity was found to be high as measured with I2 statistic (71%).ConclusionThere is very low quality evidence ECG screening decreases risk of sudden cardiac death in young athletes and military members. Decisions need to consider evidence that ECG screening could also increase risk of sudden cardiac death based on the findings of meta-analysis.PROSPERO RegistrationCRD42019125560Key PointsECG screening of athletes has been shown to be more effective than history and physical examination alone to diagnose conditions which put the athlete at risk for sudden cardiac arrest or death (SCA/D). Few data are available to answer the question of the effectiveness of ECG screening in preventing SCA/D in young athletes.We identified only four published accounts (3 full papers and one conference abstract) of non-randomized trials reporting on the effectiveness of ECG screening to prevent SCA/D in young athletes and military members. The quality of the published evidence is judged to be of very low quality to answer the question of whether ECG screening prevents episodes of SCA/D. No difference was identified between screened and non-screened athletes in data synthesis of two of the published articles eligible for meta-analysis (RR 0.58; 95%CI 0.23, 1.45).