INTRODUCTION — Sudden cardiac death (SCD) associated with athletic activity is a rare but devastating event. Victims can be young and apparently healthy, and while many of these deaths are unexplained, a substantial number harbor underlying undiagnosed cardiovascular disease. As a result, there is great interest in early identification of at-risk individuals for whom appropriate activity restrictions can be implemented to minimize the risk of SCD.
The majority of SCD events in athletes are due to malignant arrhythmias, usually ventricular tachycardia (VT) or ventricular fibrillation (VF). In individuals with certain cardiac disorders (eg, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, etc), athletics may increase the likelihood of VT/VF in two ways:
●Prolonged physical training may induce changes in cardiac structure (eg, interstitial fibrosis, disruption of normal myocardial architecture, dilation of right and left ventricle) in susceptible individuals that harbor a pathologic arrhythmogenic substrate.
●The immediate physiologic demands of intense athletics (eg, hemodynamic overload, catecholamine release, electrolyte imbalance) may trigger malignant arrhythmias in susceptible individuals with underlying cardiac abnormalities.
As with screening for any condition, the primary purpose of screening athletes for cardiac pathology is to identify patients at higher risk of SCD whose prognosis could be improved with an intervention (in this case, activity restriction or modification, or other specific therapy targeted at the underlying pathology). The approach to screening athletes depends, in part, upon the age of the athlete along with the anticipated level of activity (ie, competitive versus recreational athletics).
The approach to screening athletes for underlying cardiac disease that might predispose to SCD, including whom to screen and how, will be reviewed here. Issues related to the management of athletes with known disease as well as the broader range of arrhythmias and conduction disturbances that occur in athletes are discussed separately. (See "Athletes: Overview of sudden cardiac death risk and sport participation" and "Athletes with arrhythmias: Electrocardiographic abnormalities and conduction disturbances" and "Athletes with arrhythmias: Treatment and returning to athletic participation".)
A separate issue is screening asymptomatic persons, particularly men over age 50, who are about to begin a recreational exercise program. The exercise prescription is also important in older individuals who are beginning to exercise. The approach to recreational exercise and the prescription of exercise for cardiovascular disease prevention are discussed in greater detail separately. (See "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease", section on 'The exercise prescription'.)
DEFINITIONS — Although definitions sometime vary from study to study, it is important to define the populations of athletes as well as the level of competition in which the athletes are engaged.
●Young athletes – Most commonly, "young athletes" refers to those in high school and college, but applies in general to individuals under age 35 in whom SCD is usually due to a variety of congenital heart diseases.
●Masters athletes – Adult, or "masters," athletes include individuals over age 35 in whom SCD is most commonly due to coronary heart disease. Such sports programs primarily include apparently normal and healthy individuals over the age of 35, although many participants are greater than 50 and up to 80 years of age.
●Competitive athletes – Competitive athletes engage in organized team or individual sports in which there is regular competition, placing a premium on achievement. This definition implies that individuals are regularly engaged in high levels of training and competition and may not have the will or the judgment to limit their activity. This most frequently applies to high school, college, and professional sports.
●Recreational athletes – Recreational athletes generally participate for health and/or enjoyment purposes and do not typically have the same pressures to excel. Activity levels may still be vigorous, and the distinction from competitive athletics may be elusive in the individual case. However, defining recreational athletics separately permits the development of guidelines for noncompetitive athletes with cardiovascular disease.
WHICH ATHLETES ARE AT RISK? — For persons with an underlying cardiac disorder, both competitive and recreational athletics can potentially increase the risk of SCD, although the risk is related to the severity of the underlying pathology and the level of exertion. Athletes under 35 years of age are far more likely to suffer SCD from an underlying inherited structural heart disease (eg, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, congenital coronary artery anomalies, Marfan syndrome, etc) or an inherited arrhythmia syndrome (eg, long QT syndrome, Brugada syndrome, etc), while those over 35 years of age are more likely to have coronary heart disease. A more detailed discussion of the epidemiology and the various pathologies associated with SCD in athletes is presented separately. (See "Athletes: Overview of sudden cardiac death risk and sport participation".)
RECOMMENDATIONS FOR SCREENING BY EXPERT GROUPS — Professional societies in both North America and Europe have published recommendations for pre-participation screening for young athletes [1-7]. While these various publications are in agreement regarding the need for screening, and largely in agreement with the approach to screening, the most significant difference is that the American groups recommend a preparticipation history and physical examination alone without further routine testing, while the Europeans include a standard 12-lead electrocardiogram (ECG), mostly based upon the experience of a national screening program that has been in effect in Italy since 1982 [5,8].
North American recommendations — North American groups making recommendations for cardiovascular preparticipation screening of competitive athletes have made separate recommendations for high school or college athletes and for masters athletes (over 35 years of age) [1,4,7].
Younger athletes (NA) — North American professional society recommendations for preparticipation screening in younger athletes emphasize the importance of a complete personal and family history along with a physical examination by an appropriately trained health care worker, while routine use of 12-lead ECG, exercise testing, echocardiography, or any other testing is not recommended. These recommendations were updated in 2015 [9] for athletes between ages 12 and 25 years of age to include 14 elements, although the suggested approach is similar to that of earlier publications that promoted 12 elements [1-3,7].
●An initial complete personal and family history and physical examination should be performed before beginning training and competition. Fourteen major points to be included were defined, including elements from personal history, family history, and physical examination:
•Personal history
-Exertional chest pain/discomfort
-Unexplained syncope/near-syncope judged not to be neurally mediated (vasovagal)
-Excessive exertional and unexplained dyspnea/fatigue
-Palpitations
-Prior recognition of a heart murmur
-Elevated systemic blood pressure
-Prior restriction from participation in sports
-Prior testing for the heart, ordered by a clinician
•Family history
-Premature death in one relative (sudden and unexpected, or otherwise) before age 50 years due to heart disease
-Disability from heart disease in a close relative <50 years of age
-Specific knowledge of certain cardiac conditions in family members, including hypertrophic or dilated cardiomyopathy, long-QT syndrome or other ion channelopathies, Marfan syndrome, or clinically important arrhythmias
•Physical examination
-Heart murmur (by auscultation in supine and standing positions or with Valsalva maneuver) (table 1)
-Femoral pulses (to exclude aortic coarctation)
-Physical stigmata of Marfan syndrome (see "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders", section on 'Clinical manifestations of MFS')
-Brachial artery blood pressure (sitting position, preferably in both arms)
●Routine ECG, echocardiography, and/or exercise testing are not recommended, based upon both practical and cost-efficiency considerations, as well as the implications of borderline or false-positive screening tests. The expert panel felt that these limitations prohibited the implementation of national standards that included noninvasive screening tests. However, the panel also stated that it did not oppose smaller scale programs that included such tests, provided that they were "well designed and prudently implemented."
Athletic screening should be performed by a health care worker with the requisite training, medical skills, and background to reliably obtain a detailed cardiovascular history, perform a physical examination, and recognize heart disease. To minimize inaccuracies due to poor compliance and inadequate medical knowledge, parents should be responsible for filling out the history form for minors.
Masters athletes (NA) — North American professional society recommendations for pre-participation screening in masters athletes also emphasize the importance of a complete personal and family history along with a physical examination by an appropriately trained health care worker. In contrast to the recommendations for younger patients, some expert groups suggest a 12-lead ECG in athletes over 40 years of age (although the European professional societies consider age 35 years and above as masters athletes), and exercise testing is recommended for some masters athletes deemed to be at higher risk of atherosclerotic cardiovascular disease [4].
●An initial complete personal and family history and physical examination should be performed before beginning training and competition. Twelve major points to be included were defined, including elements from personal history, family history, and physical examination:
•Personal history
-Exertional chest pain/discomfort
-Exertional dyspnea
-Syncope (judged probably arrhythmic)
-Fatigability
-Prior recognition of a heart murmur
-Elevated systemic blood pressure
•Family history
-Premature death in one relative (sudden and unexpected, or otherwise) before age 50 years due to heart disease
-Disability from heart disease in a close relative <50 years of age
•Physical examination
-Heart murmur (by auscultation in supine and standing positions or with Valsalva maneuver)
-Femoral pulses (to exclude aortic coarctation)
-Physical stigmata of Marfan syndrome (see "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders", section on 'Clinical manifestations of MFS')
-Brachial artery blood pressure (sitting position, preferably in both arms)
●Whether or not to screen routinely with a 12-lead ECG in all masters athletes remains debated. While the American Heart Association recommends a routine ECG for all masters athletes >40 years of age, the United States Preventive Services Task Force (USPSTF) recommends against routine ECG in asymptomatic low-risk patients and made no recommendation (due to insufficient evidence) in asymptomatic intermediate- to high-risk patients [4,10]. Of note, the USPSTF recommendation was directed toward all asymptomatic adults and does not specifically comment on the use of routine screening ECG in athletes.
●Exercise (treadmill) testing is recommended for masters athletes who have a moderate-to-high cardiovascular risk profile for coronary heart disease; this risk profile includes men >40 years of age and women >50 years of age (or postmenopausal) with one or more independent coronary risk factors (hypercholesterolemia, hypertension, cigarette smoking, diabetes mellitus, or a history of myocardial infarction or sudden death in a first degree relative <60 years old) [4,11].
An exercise test is also recommended for masters athletes ≥65 years of age even in the absence of other risk factors (other than aging) or symptoms.
European recommendations — Similar to the North American expert groups, European expert groups making recommendations for cardiovascular preparticipation screening of competitive athletes have made separate recommendations for younger competitive athletes and for masters athletes (over age 35 to 40 years) [5,12]. The most significant difference between the North American and European guidelines is the European recommendation of a 12-lead ECG for all young athletes (<35 years). In addition, the European guidelines recommend that the evaluation be performed by a clinician, while the North American guidelines recommend a trained health care worker.
Younger athletes (European) — European professional society recommendations for pre-participation screening in younger athletes emphasize the importance of a complete personal and family history along with a physical examination by a clinician with specific training. Additionally, routine use of 12-lead ECG is recommended for all athletes [5].
●An initial complete personal and family history and physical examination should be performed before beginning training and competition. The pertinent components of the history and physical examination are the same as in younger athletes from North America. (See 'Younger athletes (NA)' above.)
●All athletes should have a 12-lead ECG. Athletes with an abnormal ECG (ECG abnormalities are defined by specific recommendations) (table 2 and table 3 and figure 1) should undergo a more detailed ECG review (table 4A-B) and will typically need additional diagnostic testing to exclude significant cardiac pathology [13]. (See 'Follow-up of detected abnormalities' below.)
Masters athletes (European) — European professional society recommendations for pre-participation screening in masters athletes approach this issue by assessing both the cardiovascular risk profile (by a validated risk score form) of the candidate and the type and intensity of athletic discipline (algorithm 1) [14]. Specifically, recommendations emphasize the importance of a complete personal and family history along with a physical examination by an appropriately trained health care worker. The pertinent components of the history and physical examination are the same as in masters athletes from North America. (See 'Masters athletes (NA)' above.)
In addition, a 12-lead ECG is recommended for nearly all athletes (except those with low cardiovascular risk and entering a low-intensity sport discipline) [14]. The baseline level of physical activity and the anticipated intensity of exercise are also considered when determining the requisite evaluation.
●An initial assessment of risk is recommended for sedentary masters athletes planning to participate in a low intensity activity (eg, bowling, golfing, slow walking, etc), as well as for masters athletes who are active at baseline but planning to participate in low or moderate intensity exercise. If this risk assessment is low risk, athletes may participate without further evaluation.
●All athletes should have a standardized risk assessment, with the 2011 European position paper recommending the SCORE risk assessment.
●For masters athletes whose initial assessment is not low risk, and for all other masters athletes not listed above (ie, sedentary persons planning moderate intensity activity and all persons planning high intensity activity), a complete personal and family history and physical examination, along with an exercise ECG, should be performed by the clinician before beginning training and competition. If the exercise ECG is normal, no additional testing is advised and the athlete can engage in all competitive sports.
●Athletes with an abnormal or borderline exercise ECG (algorithm 1) should undergo additional stress testing such as stress-echocardiography or stress radionuclide myocardial perfusion imaging. The choice of these tests is guided by their diagnostic accuracy, being dependent on local expertise and by their availability. Other imaging tests are gaining popularity, such as -CMR perfusion, or CT-based FFR or stress-CT myocardial perfusion imaging, and should be considered in these circumstances.(See "Selecting the optimal cardiac stress test".)
●If the result of the imaging exercise testing is normal, the athlete can participate in all competitive sports. If the exercise test is positive (algorithm 1), preferentially CT or invasive coronary angiogram should be performed to confirm or exclude the presence and extent of CAD. In case the CT angiography is performed and shows the presence of significant lesions, according to routine clinical criteria, the patient-athlete should undergo invasive coronary angiography for appropriate treatment.
After successful treatment, the athletes should be assessed with regard to the relative risk for adverse events and, accordingly, the proper advice for sport participation follows.
Differences between North American and European recommendations — While there is widespread agreement regarding the need for screening, and in large part the recommendations on the approach to screening are largely similar, there are some differences between the North American and European professional society recommendations regarding the approach to screening. These differences are centered around the role of the ECG in athletes of all ages and nuanced differences regarding the role of stress testing in masters athletes.
●The most significant difference is that the American groups recommend a preparticipation history and physical examination alone without further routine testing, while the Europeans include a standard 12-lead ECG along with preparticipation history and physical examination in all age groups, mostly based upon the experience of a national screening program that has been in effect in Italy since 1982 [5,8].
●For masters athletes, European professional societies recommend exercise ECG testing (with additional cascade testing to confirm or exclude obstructive atherosclerotic CAD as indicated) for all masters athletes ≥35 years of age, whereas North American societies only advocate exercise testing in moderate-to-high-risk athletes ≥35 years of age, patients with known coronary artery disease (with testing to be performed on the patient’s usual medications), and for all masters athletes ≥65 years of age, even if asymptomatic [15,16].
Frequency of repeat screening — Athletes without any identified abnormalities during screening are able to participate in athletics, but should undergo periodic re-screening as long as they are athletically active.
●North American experts recommend that high school students receive a comprehensive history and physical examination every two years, with an interim history during the intervening years, while college athletes should have an interim history and blood pressure measurement annually in each of the subsequent three to four years [3,8].
●European experts recommend that all younger athletes should have screening evaluations repeated at least every two years [5].
●For masters athletes, no specific recommendations are provided by the professional societies. However, in consideration of the aging process and the evolving nature of ischemic heart disease, some of our experts will repeat the screening every one to four years depending on the apparent risk, while others optimize medical therapy for coronary heart disease risk factors and counsel athletes on the symptoms of coronary heart disease and the importance of immediate medical attention if symptoms arise.
Efficacy of screening programs to detect cardiovascular disease — There are few data and no randomized trials on the impact screening programs have on the incidence of SCD in athletes. In addition, there are no direct comparisons of the North American and European approaches to screening. Observational data are limited by the low incidence of SCD and the heterogeneity of both populations studied and screening protocols.
The following are examples of the frequency of abnormalities detected during screening:
●Among a series of 32,652 Italians who underwent routine pre-participation screening that included an ECG, the prevalence of markedly abnormal ECG patterns suggestive of significant structural heart disease was <5 percent [17].
●The proportion of abnormal ECG patterns requiring additional testing (echocardiography) was 8.9 percent in a different series of 33,735 Italian athletes who were screened with history, physical, ECG, and modified stress test over a 17-year period [17,18]. The most common cardiovascular abnormalities were arrhythmias and conduction abnormalities (38 percent), hypertension (27 percent), and mitral valve disease (21 percent).
●In a systematic review and meta-analysis of screening strategies, which included data from 15 studies involving 47,137 athletes, screening athletes with an ECG was significantly more sensitive than history alone or physical examination alone [19]. The sensitivity and specificity of various screening approaches were as follows:
•ECG – 94 percent sensitive, 93 percent specific
•History – 20 percent sensitive, 94 percent specific
•Physical examination alone – 9 percent sensitive, 97 percent specific
There was a moderate amount of heterogeneity among the studies reviewed, with another limitation being that the criteria for an abnormal ECG result varied between studies.
●In a study (published after the meta-analysis) that included 11,168 adolescent English athletes (mean age 16.4 years) who underwent comprehensive cardiac screening (including a health questionnaire, physical examination, ECG, and echocardiography), 42 athletes (0.4 percent) were found to have disorders associated with sudden cardiac death, and 225 additional athletes (2 percent) were found to have congenital or valvular abnormalities [20]. After screening, SCD occurred in eight athletes after a mean interval of 6.8 years, for an incidence of approximately 1 per 14,800 person-years, which approaches the SCD incidence reported in male college basketball players (1 per 9000). A total of six athletes with a negative screen suffered SCD nearly seven years after initial evaluation (five from a cardiomyopathy). Six of the eight athletes who suffered SCD had normal initial screening results, but no repeated evaluations over the subsequent seven-year mean follow-up. This study highlights that a single screen in adolescence does not exclude the later development of genetic or acquired cardiac disease.
Impact of screening program on the outcome — There are little data that evaluate the efficacy of screening programs on outcomes. The only positive data come from an observational study from Italy (where athletic screening has been mandatory since 1982) in which all SCD in athletic and nonathletic populations between the years 1979 and 2004 was recorded, with the annual incidence of SCD in athletes decreasing from 3.6/100,000 person-years in 1979 to 1980 to 0.4/100,000 person-years in 2003 to 2004 (89 percent reduction) [21]. Notably, there was no change in the incidence of SCD among non-athletes over the same time period.
CHALLENGES TO WIDESPREAD SCREENING — Due to the devastating nature of sudden cardiac death and the potential of noninvasive testing to detect many of the associated cardiac disorders, there has been a strong interest in screening athletes prior to athletic participation. However, there are a number of obstacles to implementation of the screening, including:
●The large number of competitive athletes. As an example, in the United States alone, there are approximately four million high school athletes and 500,000 college athletes.
●The low prevalence of underlying heart disease, estimated at approximately 0.3 percent of the athletic population [1].
●The number of diseases to be considered, each with distinct diagnostic criteria and optimal testing modalities. (See "Athletes: Overview of sudden cardiac death risk and sport participation", section on 'Etiology of sudden death'.)
●The impact of test sensitivity and specificity and the implications of false positive or false negative results, which have been tempered by the introduction of the new criteria to interpret the ECG in athletes, but nevertheless is not trivial. (See "Evidence-based approach to prevention", section on 'Performance of screening tests'.)
●The uncertainty of whether restricting athletic activity in individuals with certain types of heart disease actually reduces the individual risk and substantially modifies the outcome.
●The logistic requirements to implement a screening program on a national basis (including the class of expert physicians capable of running the screening and managing athletes, the access to the diagnostic testing required, and the equal opportunities for all athletes to access the screening program).
●The legal consequences associated with improper conduct of the screening (including inappropriate interpretation of the electrocardiogram or other testing performed in athletes, legitimacy for school or athletic associations to screen individuals, management of the sensitive information describing the screening results, and consequences of the final recommendations on the individual athlete's school grant or job opportunities).
In combination, these issues have a substantial impact on both the feasibility and the cost-effectiveness of screening the large population of athletes.
OUR APPROACH TO SCREENING — Our experts all agree on the importance of screening athletes to identify those at increased risk for sudden death. However, they differ in their opinions about the optimal clinical approach, most notably regarding the role of electrocardiography (ECG).
●Beginning with high school (age 13 to 14 or older) age, we screen all competitive athletes (from both the younger and masters age groups).
●We perform an initial complete personal and family history and physical examination, including all key elements, prior to beginning training and competition. (See 'Younger athletes (NA)' above and 'Masters athletes (NA)' above.)
●Our experts have different approaches to screening with an ECG:
•Most of our experts do not routinely obtain an ECG in athletes under 35 years of age.
•Some experts do routinely obtain an ECG in athletes under 35 years of age.
•Most of our experts do routinely obtain an ECG and perform a standardized risk assessment for coronary heart disease in all athletes age 35 years or older.
●We recommend exercise treadmill testing in patients over 65 years of age; however, we perform exercise treadmill testing even in patients between ages 35 and 65 years if the athlete is deemed to have a moderate-to-high risk of coronary heart disease and/or is engaged in a very intensive sport competition (eg, marathon running, triathlon, long distance cycle racing). (See 'Masters athletes (NA)' above and 'Masters athletes (European)' above.)
●We repeat screening in younger athletes every two years. For masters athletes, some of our experts will repeat the screening every one to four years depending on the apparent risk, while other experts optimize medical therapy for coronary heart disease risk factors, and counsel athletes on the symptoms of coronary heart disease and the importance of immediate medical attention if symptoms arise.
Patients with abnormal findings on screening examination require focused follow-up depending on the screening abnormality identified. (See 'Follow-up of detected abnormalities' below.)
FOLLOW-UP OF DETECTED ABNORMALITIES — The follow-up evaluation of abnormalities detected during screening history, physical examination, or 12-lead electrocardiography (ECG; when performed) will vary depending on the specific abnormalities or suspected underlying pathology [1,5,22]. Patients with abnormal findings may require one or more of the following: ambulatory ECG monitoring, echocardiography, exercise treadmill testing, and/or cardiac magnetic resonance (CMR) imaging. As examples:
●Echocardiography is indicated for patients with a pathologic heart murmur and/or suspected structural heart disease.
●Exercise treadmill testing is indicated for patients with chest pain during exertion or for those with exertion-induced syncope or arrhythmias.
●Ambulatory ECG monitoring is indicated for patients with palpitations or syncope of suspected cardiac origin.
●CMR imaging may be indicated for patients with suspected arrhythmogenic conditions (including hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy).
●Additional screening of first-degree relatives should be performed for athletes with a diagnosed genetic disorder (eg, hypertrophic cardiomyopathy, Marfan syndrome, etc).
Detailed discussion regarding the evaluation of specific cardiac conditions is presented separately. (See "Hypertrophic cardiomyopathy: Clinical manifestations, diagnosis, and evaluation" and "Congenital and pediatric coronary artery abnormalities" and "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders" and "Congenital long QT syndrome: Diagnosis" and "Brugada syndrome: Clinical presentation, diagnosis, and evaluation" and "Arrhythmogenic right ventricular cardiomyopathy: Diagnostic evaluation and diagnosis".)
SUMMARY AND RECOMMENDATIONS
●Sudden cardiac death (SCD) associated with athletic activity is a rare but devastating event. Victims are usually young and apparently healthy, and while many of these deaths are unexplained, a substantial number harbor underlying undiagnosed cardiovascular disease. The majority of SCD events in athletes are due to malignant arrhythmias, usually ventricular tachycardia or ventricular fibrillation. (See 'Introduction' above.)
●Professional societies in both North America and Europe have published recommendations for preparticipation screening for young athletes (those younger than 35 years of age) that agree regarding the need for screening. While the societies are largely in agreement with the approach to screening (including personal history, family history, and physical examination for all athletes), the most significant difference is that the American groups recommend a pre-participation history and physical examination alone without further routine testing, while the Europeans include a standard 12-lead electrocardiogram (ECG). (See 'Recommendations for screening by expert groups' above.)
●There are few data and no randomized trials on the impact screening programs have on the incidence of SCD in athletes. In addition, there are no direct comparisons of the North American and European approaches to screening. Observational data are limited by the low incidence of SCD and the heterogeneity of both populations studied and screening protocols. (See 'Impact of screening program on the outcome' above.)
●Due to the devastating nature of SCD and the potential to detect many of the associated disorders with noninvasive testing, there is a strong incentive to screen athletes for these disorders prior to athletic participation. However, there are a number of obstacles to widespread implementation of screening, including the large numbers of competitive athletes, low prevalence of congenital heart disease, and the impact of uncertain or false-positive results, as well as logistic inadequacies and legal considerations. (See 'Challenges to widespread screening' above.)
●We agree with the professional societies on the importance of screening athletes prior to participation to identify those at increased risk for sudden death. (See 'Our approach to screening' above.)
•Screening should include a complete personal and family history and physical examination in all athletes of any age.
•We suggest performing a screening ECG in athletes age 35 years or older (Grade 2C).
•Our experts have different approaches for performing a screening ECG in younger athletes.
•We suggest performing an exercise stress test in athletes age 35 years or older if the athlete is deemed to have a moderate-to-high risk of coronary heart disease and/or is engaged in a very intensive sport competition (Grade 2C).
•Screening should be repeated at periodic intervals depending on the age and perceived risk of the individual athlete.
