The cause of SCD is usually attributed to an underlying heart problem (most commonly genetic) which is unmasked by the exercise. Exercise causes the heart to fibrillate, and then stop. The athlete collapses suddenly and if not resuscitated can die immediately, or within minutes.

• Exercise and acute cardiovascular events placing the risks into perspective: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism and the Council on Clinical Cardiology (PDF  - 255 KB), Thompson P, Franklin B, Balady G, Blair S, Corrado D, Estes N, Fulton J, Gordon N, Haskell W, Link M, Maron B, Mittleman M, Pelliccia A, Wegner N, Willich S and Costa F, Circulation, Volume 115, Issue 17 (2007). Substantial evidence supports the relationship between habitual physical activity and a reduction in coronary heart disease events, but vigorous activity can also acutely and transiently increase the risk of sudden cardiac death and acute myocardial infarction in susceptible persons. This scientific statement discusses the potential cardiovascular complications of exercise, their pathological substrate, and their incidence and suggests strategies to reduce these complications. Exercise-associated acute cardiac events generally occur in individuals with structural cardiac disease. Hereditary or congenital cardiovascular abnormalities are predominantly responsible for cardiac events among young individuals, whereas atherosclerotic disease is primarily responsible for these events in adults. The absolute rate of exercise-related sudden cardiac death varies with the prevalence of disease in the population. The incidence of both acute myocardial infarction and sudden death is greatest in those individuals who are less physically active during their lifetime. Maintaining physical fitness through regular physical activity may help to reduce cardiac events because a disproportionate number of events occur in least physically active subjects performing unaccustomed physical activity. One estimate of exercise induced death among high school and college athletes in the United States was one per 133,000 men and one per 769,000 women, but the rate may vary by sport. The incidence of sudden cardiac death among the general population may be several times the rate observed among athletes. Although vigorous exercise may increase the risk of a cardiovascular event during or soon after exertion in both young subjects with inherited cardiovascular disease and adults with occult or diagnosed cardiac disease; there is no evidence to suggest that the risks of physical activity outweigh the benefits for healthy subjects. Indeed, the converse appears to be true.
• Sudden cardiac death in young athletes, Basavarajaiah S, Shah A and Sharma S, Heart, Volume 93, Issue 3 (2007). Most cases of sudden cardiac death in young athletes (below the age of 35 years) are caused by inherited cardiomyopathies, notably hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy.
• Sudden death in competitive athletes (PDF  - 614 KB), Pigozzi F and Rizzo M, Clinics in Sports Medicine, Volume 27, Issue 1 (2008). Sudden death in athletes is an extremely rare event, yet no less tragic for its infrequency. Up to 90% of these deaths are due to underlying cardiovascular diseases and therefore categorised as sudden cardiac death (SCD). The causes of SCD among athletes are strongly correlated with age. In young athletes (<35 years), the leading causes are congenital cardiac diseases, particularly hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and congenital coronary artery anomalies. Most deaths in older athletes (>35 years) are due to coronary artery disease. 

Estimates on the risk of SCD vary greatly among studies. Differences in the estimated risk of SCD may be attributed to many factors that affect the sample population, including: (1) the specificity of the sample (i.e. one sport or multiple sports); (2) gender (i.e. males appear to be at greater risk); (3) ethnic background (i.e. African-American athletes appear to be at greater risk); (4) age (i.e. college age athletes appear to be at greater risk than high school age athletes); and (5) environmental conditions (i.e. average temperature, humidity, etc.). In addition, different data sets, data collection methodologies, and reporting formats may be used.

Studies conducted in the United States report the incidence of SCD among NCAA Division I (college) basketball athletes at 1 death per 5,200 athlete years, and overall (all sports) among college athletes the SCD rate was 1 death in 8,254 athlete years. A study of Minnesota high school athletes (all sports) used a different reporting methodology; estimating the incidence of SCD at 1 death in every 500,000 participants [source: Incidence, etiology, and comparative frequency of sudden cardiac death in NCAA athletes: A decade in review, Harmon K, Asif I, Maleszewski J, Owens ED, Prutkin J, Salerno J, Zigman M, Ellenbogen R, Rao A, Ackerman M and Drezner J, Circulation, published online (14 May 2015)]. Other recent reviews highlight the difficulty in assessing incidence rates, both in the US and internationally, but are beginning to argue that current rates are higher than previously estimated. .

• Incidence and Etiology of Sudden Cardiac Death: New Updates for Athletic Departments, Irfan M. Asif, , Kimberly G. Harmon, Sports Health: A Multidisciplinary Approach, (published 1 February 2017). A literature search was performed and articles were reviewed for relevance and included if they contained information on the incidence of SCD in athletes or young persons up to the age of 35 years. SCD is the leading cause of death in athletes during exercise and usually results from intrinsic cardiac conditions that are triggered by the physiologic demands of vigorous exercise. Current rates of SCD appear to be at least 4 to 5 times higher than previously estimated, with men, African Americans, and male basketball players being at greatest risk. Emerging data suggest that the leading finding associated with SCD in athletes is actually a structurally normal heart (autopsy-negative sudden unexplained death).
• Incidence of sudden cardiac death in athletes: a state-of-the-art review, Kimberly G Harmon, Jonathan A Drezner, Mathew G Wilson, Sanjay Sharma, BMJ Heart, Volume 100(16), (2014). A comprehensive literature search was performed and articles were reviewed for relevance and included if they contained information on the incidence of SCD in athletes or young persons up to the age of 40. Studies with higher methodological quality consistently yielded incidence rates in the range of 1:40 000 to 1:80 000. Some athlete subgroups, specifically men, African-American/black athletes and basketball players, appear to be at higher risk. The incidence of SCD in athletes is likely higher than traditional estimates which may impact the development of more effective prevention strategies

Researchers are unsure of the precise causes or the frequency of SCD among Australia athletes and therefore, data is extrapolated from international research to assess the risk. The incidence and causes of SCD among the general Australian population has been examined, but subpopulations of athletes (versus non-athletes) are not identified.

• Causes of sudden cardiac death in young Australians, Doolan A, Semsarian C and Langlois N, Medical Journal of Australia, Volume 180, Number 3, pp110-112 (2004). Although this research is not specific to a sports setting, it provides a baseline for the incidence of sudden cardiac death within the overall number of cardiac related deaths. A review of autopsy reports from 1994 through 2002 at a major Sydney forensic medicine department found 193 cases of sudden cardiac deaths from 10,199 autopsies performed. However, the cause of sudden death could not be established in 31% of cases, although it was presumed to be due to primary arrhythmogenic disorders. Coronary artery disease occurred in 24%, hypertrophic cardiomyopathy or unexplained left ventricular hypertrophy accounted for 15%, and myocarditis in 12%.

Medical screening of athletes involves a complete medical history and current examination. Many authorities (including  institutes, academies, and professional teams) recommend including an electrocardiogram (ECG) in this process. An ECG is a device that monitors the hearts' electricity by monitoring the conductive pathways at certain locations (i.e. chest and legs). The issue of compulsory cardiac screening is somewhat contentious, as there may be a high rate of “false positives” on ECGs, which may exclude some athletes unnecessarily from sports. False positives result in further (more extensive testing) and the cost-effectiveness of screening programs has not been clearly demonstrated.

• AMSSM Position Statement on Cardiovascular Preparticipation Screening in Athletes: Current Evidence, Knowledge Gaps, Recommendations, and Future Directions, Drezner, Jonathan A., O'Connor, Francis G., Harmon, Kimberly G. Clinical Journal of Sport Medicine, Volume 26(5) - pp.347–361, (September 2016). Cardiovascular (CV) screening in young athletes is widely recommended and routinely performed before participation in competitive sports. While there is general agreement that early detection of cardiac conditions at risk for sudden cardiac arrest and death (SCA/D) is an important objective, the optimal strategy for CV screening in athletes remains an issue of considerable debate. The absence of definitive outcomes-based evidence at this time precludes AMSSM from endorsing any single or universal CV screening strategy for all athletes including legislative mandates. This statement presents a new paradigm to assist the individual physician in assessing the most appropriate CV screening strategy unique to their athlete population, community needs, and resources. The decision to implement a CV screening program, with or without the addition of ECG, necessitates careful consideration of the risk of SCA/D in the targeted population and the availability of cardiology resources and infrastructure. Importantly, it is the individual physician's assessment in the context of an emerging evidence base that the chosen model for early detection of cardiac disorders in the specific population provides greater benefit than harm.
  
• Cardiovascular Preparticipation Screening in Young Athletes: Looking Through One Lens, Irfan M. Asif, Jonathan A. Drezner, and Francis G. O’Connor, Sports Health, Volume 9(1), pp.19-21, (Jan-Feb 2017). Cardiovascular (CV) screening in young competitive athletes is recommended by the majority of medical and sports governing organizations. There is, however, substantial controversy surrounding the most appropriate screening protocol and whether to add a resting 12-lead electrocardiogram (ECG) to the preparticipation history and physical examination. Rather than continue polarized debates and contentious discourse, the American Medical Society for Sports Medicine (AMSSM) took a unique stance and formed a task force of balanced perspectives to address the current evidence and knowledge gaps regarding preparticipation CV screening in athletes from the eye of a primary care sports medicine physician. This collaborative effort1-4 is summarized in Table 1 and produced several new paradigm shifts.
  
• Cardiovascular Screening in Young Athletes: Evidence for the Electrocardiogram, Asif, Irfan M. and Drezner, Jonathan A., Current Sports Medicine Reports, Volume 15(2)pp.76–80, (March/April 2016). The primary purpose of preparticipation cardiovascular screening is to identify athletes with conditions that predispose them to SCD. Unfortunately, the traditional model in the United States of a medical history and a physical examination has limited sensitivity to detect cardiovascular disease and provides false reassurance to athletes, parents, and team officials. The addition of an ECG enhances the ability to identify disease, and modern athlete-specific ECG interpretation standards used by experienced physicians provide low false-positive rates, improving the cost-effectiveness while preserving sensitivity. These advanced protocols have the potential to improve health and safety during sport events and should be considered the best practice in high-risk athletes when the sports cardiology infrastructure and oversight are readily available.
  
• The Evidence Against Cardiac Screening Using Electrocardiogram in Athletes, Asplund, Chad A. and O’Connor, Francis G., Current Sports Medicine Reports, Volume 15(2)pp.81–85, (March/April 2016). Sudden cardiac death (SCD) in young athletes is publicly remarkable and tragic because of the loss of a seemingly healthy young person. Because many of the potential etiologies may be identified with a preparticipation electrocardiogram (ECG), the possible use of an ECG as a screening tool has received much attention. A good screening test should be cost-effective and should influence a disease or health outcome that has a significant impact on public health. The reality is that the prevalence of SCD is low and no outcome-based data exist to determine whether early detection saves lives. Further, there is insufficient screening infrastructure, and the risk of screening and follow-up may be higher than that of the actual disease. Until outcomes data demonstrate a benefit with regard to SCD, universal screening cannot be recommended.
• International criteria for electrocardiographic interpretation in athletes: consensus statement. Drezner JA, Sharma S, Baggish A, et.al., British Journal of Sports Medicine, Volume 51, pp.704-731 (2017). This statement represents an international consensus for ECG interpretation in athletes and provides expert opinion-based recommendations linking specific ECG abnormalities and the secondary evaluation for conditions associated with SCD.
• Prevalence of hypertrophic cardiomyopathy in highly trained athletes: relevance to pre-participation screening, Basavarajaiah S, Wilson M, Whyte G, Shah A, McKenna W and Sharma S, Journal of the American College of Cardiology, Volume 51, Number 10 (2008). This study sought to determine the prevalence of hypertrophic cardiomyopathy (HCM) in 3,500 elite athletes. Subjects (mean age 20.5 years) underwent 12-lead electrocardiography and 2-dimenstional echocardiography, none had a known family history of heart disease. Only 0.08% of the athletes had a nondilated left ventricular cavity and associated deep T-wave inversion that could be consistent with HCM. The prevalence of HCM in highly trained athletes appears to be rare. The researchers note that functional changes in the heart associated with HCM may have naturally selected out those individuals from competitive sports. Therefore, screening athletes with echocardiography may not be cost effective.
  
• Pros and cons of screening for sudden cardiac death in sports, Corrado D, Casso C and Thiene G, Heart, Volume 99, p1365-1373 (2013). Sudden cardiac death (SCD) among athletes, though uncommon, is a devastating sport related event. The event may be widely publicised in the news media with the implication that such a fatality is preventable. This has renewed the debate regarding the need for pre-participation cardiovascular evaluation of athletes with the inclusion of a 12-lead ECG as part of the screening protocol. This article reviews the evidence regarding SCD among athletes, to highlight the areas of controversy about pre-participation screening and to address the opposing points of view in a balanced way. The evidence suggests the questions still remain unanswered. 
• Resting ECG as screening tool for Sudden Cardiac Death: PRO and CON (PDF  - 261 KB), Lawrenz, W. and Wilhelm, M., Swiss Sports & Exercise Medcine, Volume 65(3), pp8-11, (2017).  Presents the two key statements from the cardiology experts presented at the Annual meeting of the Society for Pediatric Sports Medicine at Basel 2017. 
  
• Screening young athletes for prevention of sudden cardiac death: Practical recommendations for sports physicians. J.-C. Chatard, I. Mujika, J. J. Goiriena, F. Carré, Scandinavian Journal of Medicine & Science in Sports, Volume 26(4), (April 2016), pp.362-374. The aim of this review was to focus on (i) the incidence rate of cardiac diseases in relation to SCD; (ii) the value of conducting a questionnaire and a physical examination; (iii) the value of a 12-lead resting ECG; (iv) the importance of other cardiac evaluations in the prevention of SCD; and (v) the best practice for pre-participation screening.
• The Use of Echocardiograms in Preparticipation Examinations, Lucas, Caroline; Kerkhof, Deanna L.; Briggs, Jacilyn E.; Corrado, Gianmichel D., Current Sports Medicine Reports, Volume 16(2), pp.77-83, (April 2017). This article provides an overview of the etiology of SCD and reviews literature relating to preparticipation echocardiography, with a focus on its evolution, utility, and effectiveness. The limited echocardiogram is a potentially viable screening option yet to be thoroughly explored by experts and policymakers in the sports medicine community. 
  

The issue of screening in community level sports programs has also been a focus of the media, particularly after a sudden cardiac death incident. Such incidents usually give rise to a call for mandatory automatic external defibrillators (AEDs) being available at sports training/competition venues as a possible response. 

• Automated external defibrillators in public places: position statement from the Faculty of Sport and Exercise Medicine UK, Iqbal Z and Somauroo J, British Journal of Sports Medicine, Volume 49, Issue 21 (2015). The Faculty of Sport and Exercise Medicine (FSEM) UK has published a consensus statement to create greater awareness that prompt access to an automated external defibrillator (AED) can improve the survival rate from Sudden Cardiac Arrest.
  
• Death on the pitch brings Heartbeat of Football campaign into focus, Cockerill M, The Sydney Morning Herald (29 January 2016). In 2015 more than 25,000 Masters football (soccer) players registered in New South Wales alone. In the past two years 10 Masters players have died of heart attacks during football matches in NSW. The challenge is to minimise the risk of cardiac failure among ‘older adults’ playing in both organised leagues and social football games. The availability of defibrillators is one measure that has captured the interest of players, sporting organisations, and venue operators. The campaign Heartbeat of Football will raise money for the purchase of defibrillators for local clubs. Having a defibrillator is no guarantee, but according to cardiologist and Masters player Dr Shiva Roy, it does raise the chances of survival dramatically. Football NSW will also launch its second annual Pink Slipcampaign, encouraging every Masters player in the state to have a pre-season health check to assess their level of fitness and cardiac risk. CPR training for coaches and players, and 'first responder' officials at each club is also part of the campaign.
• Preparing for sudden cardiac arrest—the essential role of automated external defibrillators in athletic medicine: a critical review (PDF  - 138 KB), Drezner J, British Journal of Sports Medicine, Volume 43, p702-707 (2009). Sudden cardiac arrest (SCA) is a leading cause of death in exercising, apparently healthy, young athletes. Three factors—prompt recognition of SCA, the presence of a trained responder to initiate cardiopulmonary resuscitation (CPR), and access to early defibrillation through on-site automated external defibrillators (AEDs)—are critical to improving survival. This article reviews emergency response planning for SCA and highlights recent data that provide a compelling case for the essential role of AEDs in the athletic setting.
  
• The role of automated external defibrillators in athletics, Rothmier J and Drezner J, Sports Health, Volume 1, Number 1 (2009). This review summarises the role of automated external defibrillators and emergency planning for sudden cardiac arrest in an athletic setting. Relevant studies on automated external defibrillators, early defibrillation, and public-access defibrillation programs were reviewed. Recommendations from consensus guidelines and position statements applicable to automated external defibrillators in athletics were also considered. 
• Sudden cardiac arrest on the football field of play – highlights for sports medicine from the European Resuscitation Council 2015 Consensus Guidelines, Kramer E, Serratosa L, Drezner J and Dvorak J, British Journal of Sports Medicine, Volume 50, Issue 2 (2016). The European Resuscitation Council (ERC) Guidelines for Resuscitation were amended in 2015. These guidelines now include a subsection on 'cardiac arrest during sports activities'. This paper reviews four critical areas in the management of sudden cardiac arrest in a football player: (1) recognition; (2) response; (3) resuscitation, and (4) removal from the field of play. Expeditious response with initiation of immediate resuscitation at the side of a collapsed player remains crucial for survival, and chest compressions should be continued until the automated external defibrillator (AED) has been fully activated. The sideline medical team’s response to a collapsed player should occur within a maximum of 2 minutes from collapse. 

The Government of Victoria has responded to the risk of sudden cardiac death in sport by encouraging sports clubs to have an emergency action plan that may include the use of an AED. A grants program has been established to assist sports clubs and sports facilities to make AED’s more widely available.  

• Defibrillators for Sporting Clubs and Facilities Program 2015-2019, Government of Victoria, Health and Human Services, Department of Sport and Recreation. The Victorian Government provides a grants program to sporting clubs, providing them with an opportunity to acquire an automatic external defibrillator (also known as an ‘AED’) for their club or sports facility. Successful applicants receive an Automatic External Defibrillator Package that includes a high quality defibrillator, some basic training, and a minimum of three years of essential maintenance. This package will be provided by a qualified contractor engaged by the Department of Health and Human Services. Applicant clubs must be non-government and not-for-profit and participate in an organised sport recognised by Sport and Recreation Victoria or Sport Australia (formerly Australian Sports Commission).

More information on managing medical and other emergencies can be found in the Clearinghouse for Sport Critical Incident Management in Sport topic. 

The Center for Sports Cardiology at the University of Washington, School of Medicine (USA), has a robust research program that is nationally and internationally recognised. Focus areas of research include: (1) frequency and causes of SCA in young athletes; (2) the role of cardiovascular screening in athletes; (3) improving ECG interpretation in athletes; (4) developing educational resources for health providers; and (5) emergency planning and the use of defibrillators (AEDs) in sports settings. Selected publications related to SCD from the University of Washington Cardiology Program are provided in a bibliography, available online.   

Sudden cardiac death in athletes, Terrell T and Pitt J, International Journal of Athletic Therapy & Training, Volume 20, Number 3 (2015). The risk of sudden cardiac death (SCD) in a young athlete is a significant public health concern, especially for athletic trainers and sports medicine physicians. Recent studies have shown that autopsy-negative sudden unexplained death is the leading cause of SCD in young athletes, which means that electrical and ion channel diseases may play a more prominent role in these deaths than previously considered. This review examines the most common causes of SCD in athletes and how they may be managed once diagnosed.  

Sudden cardiac death in athletes, Semsarian C, Sweeting J and Ackerman M, The BMJ (2015). There is much debate worldwide regarding the implementation and extent of preparticipation screening for athletes, with the main issue being the balance between lives saved; athletes tested; psychological, ethical, and legal issues; and the economic cost. Increased education and awareness about sudden cardiac death, training in cardiopulmonary resuscitation, and accessibility to automated external defibrillators can help prevent sudden cardiac death in athletes, as well as non-athletes.

Sudden cardiac death in athletes, Schmied C and Borjesson M, Journal of Internal Medicine, Volume 275, Issue 2 (2014). A 'paradox of sport' is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death in young athletes is very low, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes.

Sudden cardiac death in the athlete: Bridging the gaps between evidence, policy, and practice, Link M and Estes M, Circulation, Volume 125, p2511-2516 (2012). The precise frequency with which these events occur in the United States remains unclear because of the absence of athletic death registries and mandatory reporting requirements. In fact, whether these events are more common in athletes is not entirely certain. In addition, significant gaps in evidence exist related to the effectiveness of screening strategies in the prevention of sudden cardiac death in athletes. There are many limitations to the available evidence supporting the notion that participation restriction improves outcomes. The effectiveness of cardiopulmonary resuscitation and automated external defibrillator (AED) programs, as implemented in US airports, has not necessarily been shown in athletes. The ongoing debate related to prediction and prevention of athletic sudden death persists because the standards of evidence-based medicine have not been fulfilled with appropriately designed randomized controlled trials. 

Sudden cardiac death in young athletes: Practical challenges and diagnostic dilemmas, Chandra N, Bastiaenen R, Papadakis M and Sharma S, Journal of the American College of Cardiology, Volume 61, Issue 10, p1027-1040 (2013). Strategies for the prevention of SCD, including preparticipation cardiovascular screening, are often endorsed by sports governing bodies, but mandatory preparticipation cardiovascular screening remains rare. Evaluation of athletes poses diagnostic difficulties, particularly differentiating between physiological adaptation to exercise, known as athlete's heart, and cardiomyopathic processes capable of causing SCD. This paper provides a detailed review regarding the etiology of SCD in young athletes and provides insight into the challenges and dilemmas faced when evaluating athletes for underlying pathological conditions. 

United States 

The body of evidence available within sports settings in the Unites States continues to be the best available, although significant limitations remain in data gathering. The debate regarding the efficacy of mandatory electrocardiogram (ECG) screening protocols and the widespread use of automatic external defibrillators (AEDs) in a sports setting is ongoing.

Prevalence of sudden cardiac death during competitive sports activities in Minnesota High School athletes, Maron B, Gohman T and Aeppli D, Journal of the American College of Cardiology, Volume 32, Issue 7 (1998). Reliable incidence data was obtained from high school sports participants in 27 sports over a 12 year period. Three sudden deaths due to cardiovascular disease occurred in competitive high school athletes (grades 10–12) during competition or practice within this period. There were 1,453,280 overall sports participations and 651,695 student athlete participants; the calculated risk for sudden death was 1 in 500,000 participations. The rare occurrence of sudden cardiac death in competitive sports underlines the limitations and cost-effectiveness of broad-based screening strategies for high school athletes. 

Another source estimates that 1-3 in 100,000 apparently healthy young athletes may develop abrupt-onset ventricular tachycardia or fibrillation and may die suddenly during exercise. Males are affected 10 times more often than females. Basketball and football players in the United States, and soccer players in the UK, appear to be at highest risk. [source: Merck Manuals for Healthcare Professionals, online, last full review/revision February 2017 by Robert S. McKelvie, MD, PhD] 

Interassociation Consensus Statement on Cardiovascular Care of College Student-Athletes. Brian Hainline, Jonathan A. Drezner, Aaron Baggish, et.al. Journal of the American College of Cardiology, Volume 67(25), (June 2016). The National Collegiate Athletic Association convened a multidisciplinary task force to address cardiovascular concerns in collegiate student-athletes and to develop consensus for an interassociation statement. This document summarizes the task force deliberations and follow-up discussions, and includes available evidence on cardiovascular risk, pre-participation evaluation, and the recognition of and response to cardiac arrest. Future recommendations for cardiac research initiatives, education, and collaboration are also provided.

Sudden Cardiac Arrest. Resources provided by the U.S. National Athletic Trainers' Association (NATA). Includes Position Statements, Consensus Statements, and Other Resources.

• While the risk of sudden cardiac arrest in young people is very small, the impacts can be catastrophic. While the causes of sudden cardiac death in athletes/patients may not be consistent, but about 2/3 of the time they are due to a heart abnormality. The best way athletic trainers can deal with these unforeseen circumstances is to prepare for it in advance and stay abreast of relevant research and resources.

Screening for sudden cardiac death before participation in high school and collegiate sports, Mahmood S, Lim L, Akram Y, Alford-Morales S and Sherin K, American Journal of Preventive Medicine, Volume 45, Number 1 (2013). Position Statement of the American College of Preventive Medicine (ACPM). The ACPM supports athlete evaluation prior to participation in high school and collegiate sports, using a standardised physical examination (such as developed by the American Heart Association) and a personal/family medical history. The ACPM does not recommend routine screening for potential sudden cardiac death (SCD) with electrocardiogram (ECG), echocardiography, and genetic testing in individuals without the presence of personal risk factors identified from family health history or current medical examination. The recommendations by ACPM address only mass screening approaches and are not targeted toward individuals who may be identified by their healthcare provider as ‘above average’ risk; these individuals may benefit from additional testing. 

Audio

• The harm and the benefit of treatment is about the same" - cardiac screening for athletes. Hans Van Braband, BMJ Talk Medicine, SoundCloud, (2016). Sudden cardiac death of young athletes needs to be avoided but does screening really help? Hans Van Braband, researcher at the Belgian Health Care Knowledge Centre, joins us to explain that the evidence for screening doesn't show benefit, and may lead to harm.
• Preventing sudden cardiac death in athletes. Christopher Semsarian, BMJ Talk Medicine, SoundCloud, (2015). Sudden cardiac death in athletes aged less than 35 years is the leading cause of medical death in this subgroup, with an estimated incidence of 1 in 50 000 to 1 in 80 000 athletes per year. it is most commonly caused by an underlying genetic heart disorder, such as hypertrophic cardiomyopathy. In this podcast Christopher Semsarian, professor of medicine at the University of Sydney, joins us to discuss the diagnosis of cardiac changes and prevention of death in this population.
• Assistant Professor Aaron Baggish, Sports Cardiologist / Boston Marathon. BMJ Talk Medicine, SoundCloud (2014). In this concise, information-rich BJSM podcast, sports cardiologist Aaron Baggish shares his expertise on the critical issue of sudden cardiac death in sport. 
• Sudden athlete deaths. ABC RN Breakfast, (8 May 2012). During this radio program the host speaks to a range of experts including Dr Peter Baquie, Medical Director of the Australian Olympic team, London 2012, Dr Andrew Macisaac, Director of Cardiology, St Vincent’s Hospital, Melbourne and Libby Trickett, Australian Olympic Swimmer.

Books

• Clinical Sports Medicine, fifth edition, Peter Brukner and Karim Khan (editors), McGraw Hill (2016). Part D: 'Management of Medical Problems, Sudden cardiac death in sport', p996-1023.
• Evidence-based Sports Medicine, second edition, Domhnall MacAuley and Thomas Best (editors), Blackwell Publishing, (2007). Chapter 2: 'Evidence-based pre-participation physical examination'.
• Pediatric Sports Medicine for Primary Care, Richard Birrer, Bernard Griesemer and Mary Cataletto (editors), Lippincott Williams & Wilkins, (2002). Chapter 17: 'Sudden death in young athletes'.
• Practical ECG for Exercise Science & Sports Medicine, Greg Whyte & Sanjay Sharma, Human Kinetics, (2010). 
• Preventing Sudden Death in Sport and Physical Activity, Douglas Casa (editor), Jones & Bartlett Learning, (2012). Chapter 2: 'Prevention of Sudden Cardiac Death in Young Athletes' and Chapter 3: 'Prevention of Sudden Cardiac Death in Older Athletes'.
• Sports Medicine for the Primary Care Physician, third edition, Richard Birrer and Francis O’Connor (editors), Taylor & Francis, (2004).

Conference presentations

• Sudden death and sport: still a long way to go [video], Vijgen J, Seventeenth annual congress of the European College of Sport Science/YouTube, (4-7 July 2012)

Reading

• Explainer: sudden death in young athletes, Chris Semsarian, Professor of Medicine, University of Sydney, The Conversation (17 April 2012). A common cause of sudden death is hypertrophic cardiomyopathy (HCM), which affects up to one in 500 people. This genetic abnormality causes the heart to continue growing, until the muscle wall becomes so thick that it begins to restrict the flow of blood to and from the heart. Tragically, genetic heart diseases are often silent, as individuals have no symptoms. Even more sadly, sudden death can be the first presenting symptom in up to half of young people who die suddenly. Elite sports people can achieve the highest levels of sporting excellence, yet be at risk of sudden cardiac arrest.
• Heart attacks of the mega-fit: how safe is extreme sport? Konrad Marshall, Canberra Times, (31 March 2018). We don’t just go for a jog any more – we train for a marathon, following in the footsteps of the greats. But when top athletes collapse from heart failure, we start to wonder: how safe is this growing culture of extreme sport?
  
• Proper emergency planning can reduce risk of death from sudden cardiac arrest in marathons, American College of Sports Medicine news release, (October 2012). Training of race medical staff and provisions for adequate equipment, including use of an automatic external defibrillator (AED), can dramatically improve survival following sudden cardiac arrest (SCA). Emergency planning with availability of AEDs throughout the race course is recommended, and if resources are limited the focus should be placed in the last four miles of the race, where the majority of SCA cases occur. Although the risk of experiencing sudden cardiac arrest during a marathon is very low – about one in 57,000 – the role of medical staff during a race is crucial to reduce response time and AED use in the treatment of SCA.
• Sudden Cardiac Death in Athletes: still much to learn. Joanna Sweeting & Christopher Semsarian, Cardiology Clinics, (published online 28 August 2016). The sudden cardiac death (SCD) of an athlete is generally unexpected and extremely traumatic. Some of the most commonly identified causes of SCD in athletes include the genetic heart diseases. Despite thorough clinical and genetic investigation, in some cases a cause of death cannot be elucidated. Further research in these areas, spanning clinical, genetic, and public health perspectives, is required to help guide clinicians and those encountering the tragedy of SCD in an athlete.
• Sudden cardiac death in young competitive athletes. Michael W. Luong, Barbara N. Morrison, Daniel J. Lithwick, et.al., BCMJ, Volume 58(3), (April 2016), pp.138-144. Sudden cardiac death in young athletes is fortunately a rare event. Worldwide, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are the most common causes. Multiple studies have tried to determine the incidence of SCD in athletes, but this has proven to be difficult because of differing definitions, inconsistent identification of causes of death, and geographic variation. An accurate incidence rate for SCD is needed to determine the cost-effectiveness of pre-participation screening programs for competitive athletes. Without an accurate incidence rate, pre-participation screening in the young competitive athlete will remain a controversial topic within international sport and medical societies. We cannot, however, ignore the fact that athletes with unrecognized heart disease may increase their risk of SCD by participating in sport. Further studies are needed to inform strategies that can reduce the burden of SCD in this population.
• Sudden Death in Young Athletes: Important Causes Not Identified by the Screening Process. Minneapolis Heart Institute Foundation, this article explains the data presented at the American College of Cardiology Scientific Sessions held in San Francisco (March 2013).
• Testing athletes for risk of cardiac disease, Brosnan M and Prior D, eLS, published online (15 October 2012). Although regular exercise offers a degree of protection from cardiovascular disease, there is a transient increase in the risk of sudden cardiac death (SCD) during athletic activity. SCD usually occurs as a result of inherited diseases of the heart's structure. These diseases may cause no symptoms prior to SCD. Many sporting bodies are now recommending pre-participation screening to identify and enforce restriction of sports participation for those most at risk of SCD. However, there is ongoing debate about the effectiveness and cost-effectiveness of such a strategy.
• Tests prepare sports for sudden-death moments. The Age (11 December 2011). This article explains the need for cardiac screening in elite athletes. 

Research

• A review of sudden cardiac death in young athletes and strategies for pre-participation cardiovascular screening, Koester M, Journal of Athletic Training, Volume 36, Number 2 p197–204 (2001). More than 20 different causes of sudden cardiac death have been described in the literature. Many attempts have been made to detect those at risk for sudden cardiac death before athletic participation. At this time, a thorough family history and physical examination are the most efficient screening methods for identifying athletes who may be at risk. 
  
• Athlete's heart: the potential for multimodality imaging to address the critical remaining questions, La Gerche A, Taylor A and Prior D, Cardiovascular Imaging, Volume 2, Number 3, p350-363 (2009). The athlete's heart syndrome refers to the morphological and electrical remodeling which occurs to varying extents dependent upon the sporting discipline. Its accurate differentiation from pathological entities is critical. This review describes the role multi-modality imaging serves in determining the limitations and consequences of intense exercise.
• Cardiac imaging and stress testing asymptomatic athletes to identify those at risk of sudden cardiac death, La Gerche A, Bagish A, Knuuti J, Prior D, Sharma S, Heidbuchel H and Thompson P, Journal of the American College of Cardiovascular Imaging, Volume 6, Issue 9, p993-1007 (2013). This review examines the controversial topic of utilising cardiac imaging for athlete pre-participation screening. Specifically, the limitations of screening for relatively rare disorders using imaging tools with uncertain or imperfect accuracy are addressed by the authors. Current evidence suggests that the accuracy of all cardiac imaging modalities is insufficient to justify their use as primary mass screening modalities in athletes. Atypical findings such as marked cardiac dilation, reduced deformation, or small patches of delayed gadolinium enhancement may be commonly encountered in well-trained athletes; but, at present, the prognostic significance of such findings is unknown. The resulting uncertainty for the clinician and athlete has the potential for psychological stress and unnecessary exclusions from competition. However, these concerns must not be confused with the extremely useful applications of cardiac imaging for the assessment of athletes with symptoms, an abnormal electrocardiogram, or a positive family history.
• Cardiorespiratory fitness and risk of sudden cardiac death in men and women in the United States: A prospective evaluation from the Aerobics Center Longitudinal Study, Jiménez-Pavón D, Artero E, Lee D, España-Romero V, Sui X, Pate R, Church T, Moreno L, Lavie C and Blair S, Mayo Clinic Proceedings, Volume 91, Issue 7 (2016). This study examined the relation between cardiorespiratory fitness (CRF) and sudden cardiac death (SCD) in a large US adult population, and the effects of hypertension, obesity, and health status on the relationship between CRF and SCD. Data came from 55,456 adults, mean age 44.2 years, (41,949 men and 13,507 women) from the Aerobics Center Longitudinal Study. The risk of SCD was found to be inversely related across incremental CRF levels  with cardiorespiratory fitness, after adjusting for potential confounders (i.e. high CRF associated with lower risk of SCD). Participants with moderate and high CRF levels had 44% and 48% significantly lower risk of SCD, respectively, than did those with low CRF levels. The risk of SCD decreased by 14% per 1-metabolic equivalent increase in fitness. Hypertension, overweight, or unhealthy individuals with moderate to high CRF levels also had lower risks of SCD than did those with the same medical conditions and lower CRF levels. 
• Costs and yield of a 15-month preparticipation cardiovascular examination with ECG in 1070 young athletes in Switzerland: implications for routine ECG screening, Menafoglio A, Di Valentino M, Segatto J, et al., British Journal of Sports Medicine, Volume 48(15), pp.1157-1161, (2014). This study aimed to assess the total costs and yield of a preparticipation cardiovascular examination with ECG in young athletes in Switzerland. Cardiovascular preparticipation examination in young athletes using modern and athlete-specific criteria for interpreting ECG is feasible in Switzerland at reasonable cost. ECG alone is used to detect all potentially lethal cardiac diseases. The results of our study support the inclusion of ECG in routine preparticipation screening.
  
• Early identification of risk factors for sudden cardiac death, Sumeet S, Nature Reviews Cardiology, Volume 7, Number 6, p318–326 (2010). The complex and dynamic nature of SCD continues to present a considerable challenge for the early identification of risk factors. A growing body of literature describes novel risk markers and predictors of SCD, such as high-risk phenotypes, genetic variants and biomarkers. This Review discusses the potential utility of these markers as early identifiers of risk and suggests a framework for the conduct of future studies.
• Etiology of Sudden Death in Sports: Insights From a United Kingdom Regional Registry. Gherardo Finocchiaro, MichaelPapadakis, Jan-Lukas Robertus et.al., Journal of the American College of Cardiology, Volume 67(18), (10 May 2016), pp.2108-2115. Conditions predisposing to SCD in sports demonstrate a significant age predilection. The strong association of ARVC and left ventricular fibrosis with exercise-induced SCD reinforces the need for early detection and abstinence from intense exercise. However, almost 40% of athletes die at rest, highlighting the need for complementary preventive strategies.
• European Resuscitation Council Guidelines for Resuscitation 2015: Section 4. Cardiac arrest in special circumstances (PDF  - 2.8 MB), Truhlar A, Deakin C, Soar J, et.al., Resuscitation, Volume 95, p148-201 (2015). Irrespective of the cause of cardiac arrest, early recognition and prompt action, including appropriate management of the deteriorating patient, early defibrillation, and high-quality cardiopulmonary resuscitation with minimal interruption of chest compressions and treatment of reversible causes, are the most important interventions. Special circumstances are divided into three parts: (1) special causes; (2) special environments, and; (3) special patients.
• Five-Year Experience with Screening Electrocardiograms in National Collegiate Athletic Association Division I Athletes, Colin Fuller, Carol Scott, Cheryl Hug-English, Wei Yang, PhD, and Andrew Pasternak, Clinical Journal of Sports Medicine, Volume 26(5), pp.369-375, (September 2016). More recent ECG screening criteria substantially reduce the abnormal ECG rate and thus the number of athletes requiring additional testing. ECG screening criteria identified the predicted number (1/300) of young athletes with serious underlying cardiovascular disease. These criteria prompt not only additional cardiovascular testing but also a more thorough cardiovascular history.
  
• Harms and benefits of screening young people to prevent sudden cardiac death. Van Brabandt Hans, Desomer Anja, Gerkens Sophie, Neyt Mattias, BMJ, (published online 20 April 2016). Sudden cardiac death of a young person on a sports field is a devastating event. Often these deaths are due to an unrecognised underlying heart condition, and screening has been proposed as a method to prevent them. However, disagreement remains about its benefits and harms.
• Incidence of sudden cardiac death in National Collegiate Athletic Association athletes, Harmon K, Asif I, Klossner D and Drezner J, Circulation, Volume 123, p1594-1600 (2011). The true incidence of sudden cardiac death (SCD) in US athletes is unknown. Current estimates are based largely on case identification through public media reports and estimated participation rates. The purpose of this study was to more precisely estimate the incidence of SCD in National Collegiate Athletic Association (NCAA) student-athletes and assess the accuracy of traditional methods for collecting data. This study concluded that current methods of data collection may underestimate the risk of SCD. Accurate assessment of SCD incidence is necessary to shape appropriate health policy decisions and develop effective strategies for prevention. 
• International criteria for electrocardiographic interpretation in athletes: consensus statement. Drezner JA, Sharma S, Baggish A, et.al., British Journal of Sports Medicine, Volume 51, pp.704-731 (2017). This statement represents an international consensus for ECG interpretation in athletes and provides expert opinion-based recommendations linking specific ECG abnormalities and the secondary evaluation for conditions associated with SCD.
• Interpretation of the Electrocardiogram in Athletes. Keerthi Prakash & Sanjay Sharma, Canadian Journal of Cardiology, Volume 32(4), (April 2016), pp.438-451. The ability to distinguish accurately between benign physiological electrical alterations and pathological ECG changes is crucial to prevent the unnecessary termination of an athlete's career and to minimize the risk of sudden death. Several recommendations currently exist to aid the physician in the interpretation of the athlete's ECG. In this review we discuss which ECG patterns can safely be considered benign as opposed to those that should prompt the physician to consider cardiac pathology.
• Is there evidence for recommending electrocardiogram as part of the pre-participation examination? Drezner J and Corrado D, Clinical Journal of Sport Medicine, Volume 21, Issue 1, p18-24 (2011). This article examines the evidence related to ECG screening in athletes and presents a contemporary model for primary prevention of SCD in sport.
• Preparticipation athletic screening including an electrocardiogram: An unproven strategy for prevention of sudden cardiac death in the athlete, Estes N and Link M, Progress in Cardiovascular Diseases, Volume 54, Issue 5, p451-454 (2012). A fundamental principle of evidence-based medicine is that clinical practice should be based on evidence derived from sufficiently robust data to ensure that the benefits, risks, and costs of an intervention are known. The authors contend that screening programs with routine electrocardiograms (ECGs) followed by restriction of at-risk individuals have not been demonstrated to be effective in decreasing the inherent risk of athletic sudden death. Although programs and policies intended to decrease sudden death are laudable, they need to be supported by further evidence and evaluation before being implemented on a large-scale basis. Currently, athletes are best protected by a strategy of secondary prevention with improvements in resuscitation and emergency action plans. 
• The Psychological Impact of Cardiovascular Screening in Young Athletes: Perspectives Across Age, Race, and Gender, Asif, Irfan M., Price, David MD, Harmon, Kimberly G. MD, Salerno, Jack C., Rao, Ashwin L., Drezner, Jonathan A., Clinical Journal of Sport Medicine, Volume 25(6), pp.464–471, (November 2015). Electrocardiogram screening does not cause excessive anxiety in US high school athletes across spectrums of age, race, and gender. Recognition of age, race, and gender-specific perspectives could improve physician–patient dialogue and support mechanisms for those diagnosed with potentially lethal cardiac disorders.
  
• Screening athletes for heart disease, Crawford M, Heart, Volume 93, Number 7 (2007). The most important reason to screen for heart disease is to prevent sudden, unexpected death. Almost all states in the USA require some type of pre‐participation screening of participants in organised sports. The idea of preventing such a low frequency event is challenging and the efficacy of any screening program would be difficult to prove. Despite these clear realities, public interest in this problem is high. Cardiac death in competitive athletes continues to be highly visible and a compelling emotional event, with significant liability concerns. These catastrophes are frequently subjected to intense public scrutiny largely because of their occurrence in young otherwise healthy‐appearing individuals, including elite participants in collegiate and professional sports. Consequently, physicians in the USA must be familiar with the issue of screening athletes for heart disease and the current recommendations for this activity. 
• Should Pre-participation Cardiovascular Screening for Competitive Athletes be Introduced in Australia? A Timely Debate in a Sport-loving Nation, La Gerche A, MacIsaac A and Prior D, Heart, Lung and Circulation, Volume 20, Issue 10, p629-633 (2011). Pre-participation screening of all competitive athletes is recommended in some countries and mandated in others. Evidence does exists that screening reduces sudden death, but the potential negative impact of exclusion from sport has not been quantified. Australian sporting organisations must consider whether screening is feasible, effective and affordable. It is currently difficult to make this decision because substantial evidence about the scope of the problem, and whether the prevalence of sudden cardiac death in Australia is similar or different to other countries, does not exist. We review the available evidence for and against screening and propose that systematic collection of Australian data is required before routine pre-participation cardiac screening can be mandated in Australia. 
• Sports and Exercise in Athletes with Hypertrophic Cardiomyopathy, Craig Alpert, Sharlene M. Day, and Sara Saberi, Clinics in Sports Medicine, Volume 34(3), pp.489-505, (2015). Current guidelines of both American and European cardiology societies recommend that patients with HCM refrain from all but low-intensity sports independent of implantable cardioverter-defibrillator (ICD) use.Despite theoretic concerns that exercise can increase the risk of SCD, many patients with HCM have safely participated in physical activity. Improved quantification of risk of a given individual for a given activity, coupled with better emergency preparedness, may allow most patients with HCM to participate in physical activity in a safe manner.
• Standardised criteria improve accuracy of ECG interpretation in competitive athletes: a randomised controlled trial, Daniel J Exeter, C Raina Elley, Mark L Fulcher, Arier C Lee, Jonathan A Drezner, Irfan M Asif, British Journal of Sports Medicine, Volume 48(1), pp.1167-1171, (2014). Screening to prevent sudden cardiac death remains a contentious topic in sport and exercise medicine. The aim of this study was to assess whether the use of a standardised criteria tool improves the accuracy of ECG interpretation by physicians screening athletes. Correct ECG interpretation was higher in the intervention group, 88.4% (95% CI 85.7% to 91.2%), than in the control group, 82.2% (95% CI 78.8% to 85.5%; p=0.005). Sensitivity was 95% in the intervention group and 92% in the control group (p=0.4), with specificity of 86% and 78%, respectively (p=0.006). There were 36% fewer false positives in the intervention group (p=0.006). 
  
• Sudden cardiac death: mandatory exclusion of athletes at risk is a step too far, Anderson L, Exeter D and Bowyer L, British Journal of Sports Medicine, Volume 46, Issue 5, p331 (2012). There is a push for a system which involves screening and mandatory exclusion from sports participation of those at risk. The authors argue that while screening can provide useful information to at-risk athletes, making decisions affecting their future athletic careers through mandatory exclusion is paternalistic and such decisions are not rightfully within the domain of medicine.
• Sudden Cardiac Death in Athletes. Wasfy MM, Hutter AM, Weiner RB, Methodist DeBakey Cardiovascular Journal, Volume 12(2), (2016), pp.76-80. There are clear health benefits to exercise; even so, patients with cardiac conditions who engage in exercise and athletic competition may on rare occasion experience sudden cardiac death (SCD). This article reviews the epidemiology and common causes of SCD in specific athlete populations. There is ongoing debate about the optimal mechanism for SCD prevention, specifically regarding the inclusion of the ECG and/or cardiac imaging in routine preparticipation sports evaluation. This controversy and contemporary screening recommendations are also reviewed.
• Sudden cardiac death in athletes. Christopher Semsarian, Joanna Sweeting, Michael J Ackerman, BMJ, (published online 18 March 2015). There is much debate worldwide regarding the implementation and extent of preparticipation screening for athletes, with the main issue being the balance between lives saved; athletes tested; psychological, ethical, and legal issues; and the economic cost. Increased education and awareness about sudden cardiac death, training in cardiopulmonary resuscitation, and accessibility to automated external defibrillators can help prevent sudden cardiac death in athletes, as well as non-athletes. 
• Top 10 Research Questions Related to Preventing Sudden Death in Sport and Physical Activity. Katch, Rachel K.; Scarneo, Samantha E.; Adams, William M.; Armstrong, Lawrence E.; Belval, Luke N.; Stamm, Julie M.; Casa, Douglas J., Research Quarterly for Exercise & Sport, Volume 88(3), pp.251-268, (September 2017). In this article, we provided 10 key questions related to the leading causes and treatment of sudden death in sport and physical activity, where future research will support safer participation for athletes and recreational enthusiasts. The current evidence indicates that most deaths can be avoided when proper strategies are in place to prevent occurrence or provide optimal care. 
  
• Trends in sudden cardiovascular death in young competitive athletes after implementation of a pre-participation screening program, Corrado D, Basso C, Pavei A, Michieli P, Schiavon M and Thiene G, The Journal of the American Medical Association, Volume 296, Number 13, p1593-1601 (2006). This study analysed trends in incidence rates and cardiovascular causes of sudden death in young competitive athletes in Italy in relation to their participation in screening programs. Data was used from programs operating from 1982 to 2004. The annual incidence of sudden cardiovascular death in athletes decreased significantly, from 3.6 per 100,000 person-years in 1979-1980 to 0.4 per 100,000 person-years in 2003-2004; whereas the incidence of sudden death among the unscreened non-athletic population did not change significantly. During the study period, 879 athletes were disqualified from competition due to cardiovascular causes. Mortality reduction was predominantly due to a lower incidence of sudden death from cardiomyopathies that paralleled the increasing identification of these problems in athletes through screening programs.
• What can we do to reduce the number of tragic cardiac events in sport? Weiler R, Goldstein M, Beasley I, Drezner J and Dvorak J, British Journal of Sports Medicine, Volume 46, Issue 12, p897 (2012). Each young athlete lost to SCD is a powerful reminder that despite our growing knowledge, we still lack many answers to basic questions about these afflictions. We do not know the exact numbers and trends in prevalence or incidence, and do not understand the multivariable causality that triggers SCD in previously healthy athletes. We have a limited understanding of the risks of SCD in individual sports and the variable risks by gender and ethnicity. We do not fully understand why a significant proportion of SCD remains unexplained and whether screening programs have actually reduced the number of deaths and if they are cost effective. With improved medical facilities and expertise on site at sporting events, the probability of survival can be improved with quick emergency life support and defibrillation. Access to a defibrillator is a standard that should be uniform throughout all sport.