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 previously 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 sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). In individuals with certain cardiac disorders (eg, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, etc), athletics may increase the likelihood of VT/VF in two ways:
●In certain susceptible individuals (ie, with inherited arrhythmogenic cardiomyopathy), prolonged exercise training may induce adaptive changes in cardiac structure (eg, interstitial fibrosis, disruption of normal myocardial architecture, dilation of right and left ventricle) that may create pathologic arrhythmogenic substrate. This worsening of the phenotype has not been observed in hypertrophic cardiomyopathy.
●The immediate physiologic demands of intense athletics (eg, mechanical strain, increased myocardial oxygen consumption, hemodynamic overload, catecholamine release, electrolyte imbalance) may trigger malignant arrhythmias in susceptible individuals with underlying cardiac abnormalities.
The potential for SCD associated with athletic activity generates two questions:
●How should individuals be identified prior to initiating athletic activity?
●What restrictions (if any) should be placed upon individuals with known cardiovascular disease to minimize the SCD risk?
Answers to these questions are complicated and controversial and often based on limited clinical data and thus expert opinion. Answers vary based upon three factors:
●The age of the individual
●The nature of the activity (ie, competitive versus recreational athletics)
●The type of underlying heart disease
This topic will review the major etiologies of SCD in athletes and recommendations for participation in sports in the presence of various cardiac abnormalities. The broader range of arrhythmias and conduction disturbances common in athletes, including treatment and return to participation following treatment, are discussed separately. (See "Athletes with arrhythmias: Electrocardiographic abnormalities and conduction disturbances" and "Athletes with arrhythmias: Clinical manifestations and diagnostic evaluation" and "Athletes with arrhythmias: Treatment and returning to athletic participation".)
The recommended approaches to preparticipation screening of athletes are also presented separately. (See "Screening to prevent sudden cardiac death in competitive athletes".)
DEFINITIONS — Although definitions 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 ≥35 years of age in whom SCD is most commonly associated with coronary heart disease. Such sports programs primarily include apparently normal and healthy individuals ≥35 years of age, although many participants are greater than 50 up to 80 years or more of age.
●Competitive/elite athletes – Competitive/elite 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-level 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.
COMPETITIVE VERSUS RECREATIONAL ATHLETICS — The literature on SCD during exertion has largely focused on competitive athletics. However, some recreational athletics can be as vigorous as competitive sport, so recreational activity limitations are also important in individuals with one of the cardiovascular diseases commonly associated with SCD . While the incidence of SCD appears to be higher in competitive versus recreational athletes, the total number of SCDs is actually greater in recreational athletes, due to the sheer numbers of persons engaging in recreational activity and the less stringent rules for preparticipation evaluation in the latter . The balance between the risks and benefits of athletic activity depends upon several factors, including baseline fitness level, the nature and intensity of athletic activity, the presence and extent of cardiac disease, and the psychologic and physical benefit from sport.
For patients with a congenital disorder, with either structural or arrhythmic substrate, the possible increased risk associated with participation in athletic activity generally requires some restriction on athletic activity. However, it must be acknowledged that these restrictions are usually based on expert opinion and not controlled studies. Historically, patients with known genetic disorders that may predispose to SCD (eg, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, Marfan syndrome, long QT syndrome) have been advised to avoid exercise activities with the following characteristics:
●"Burst" exertion, involving rapid acceleration and deceleration, as is common in sprints, basketball, tennis, and soccer. Activities with stable energy expenditure, such as jogging, biking on level terrain, and lap swimming are preferred.
●Extreme environmental conditions (temperature, humidity, and altitude) that impact blood volume and electrolytes.
●Systematic and progressive training load focused on achieving higher levels of conditioning and excellence.
However, paternalistic guidance has been changed to a contemporary approach for a shared decision-making process, which involves the athlete in the discussion of risk and benefit. Patients with unusual or high-risk clinical features may require greater restriction. These features include a history of syncope or presyncope (especially during exertion), prior arrhythmic episodes, or an implantable cardioverter-defibrillator (ICD). However, for most other individuals, including those with stable coronary heart disease, the overall benefits of regular exercise far outweigh the risks. A prudent and gradually progressive exercise program is therefore appropriate in most cases . (See "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease" and "The benefits and risks of aerobic exercise".)
OUR APPROACH TO PARTICIPATION IN ATHLETICS (AND SPORT ACTIVITY IN GENERAL) — Our approach to participation in sport activity, either recreationally or competitively, is in general agreement with that of the American Heart Association :
●Physically active asymptomatic individuals without known cardiovascular disease – These individuals may continue their usual moderate or vigorous exercise and progress gradually as tolerated. Those who develop signs or symptoms of cardiovascular disease should discontinue exercise and seek guidance from a medical professional before resuming exercise of any intensity.
●Physically active asymptomatic individuals with known cardiovascular disease – Those who have been medically evaluated within 12 months may continue a moderate-intensity exercise program unless they develop signs or symptoms, which requires immediate cessation of exercise and medical reassessment.
●Physically inactive individuals without known cardiovascular disease – These persons may begin light- to moderate-intensity exercise without medical guidance and, provided they remain asymptomatic, progress gradually in intensity as recommended by current American College of Sports Medicine (ACSM) guidelines.
●Physically inactive individuals with known cardiovascular disease or signs/symptoms that are suggestive cardiovascular disease – Such patients should seek medical guidance before starting an exercise program, regardless of the intensity.
INCIDENCE OF SUDDEN CARDIAC DEATH — It is widely acknowledged that SCD is one of the leading medical causes of death in athletes, although its exact incidence remains controversial. The best available evidence, together with a close examination of reporting methods for case identification and population definitions, suggests that an overall incidence of between 1:50,000 and 1:100,000 per year in young competitive athletes is a reasonable estimate based on existing information from retrospective cohort studies and prospective observational and cross-sectional studies [3-5]. This rate is notably higher in older adults, closer to 1:7000 healthy adult athletes per year .
Incidence data are imprecise since most are derived from retrospective analyses, and incidence varies depending upon the intensity of exercise, the athletic population considered, the time period of observation, and whether the definition of athletic SCD encompasses SCD outside of sport/exercise [6-10]. Use of media reports or catastrophic insurance claims as the primary method for case identification has been demonstrated to underestimate (by approximately 50 percent) the risk of SCD in athletes . Male athletes are consistently found to be at greater risk, and there appears to be a disproportionately higher risk among male African American athletes.
Using data from the Rescue Registry cardiac arrest database, which contains data from all out-of-hospital sudden cardiac arrests (SCA, which includes deaths and resuscitated arrests) attended by paramedics in the province of Ontario, Canada, investigators retrospectively reviewed the incidence of SCA between 2009 and 2014 among an estimated 350,000 competitive athletes ages 12 to 45 years (in total 2.1 million athlete-years) . Among the 3825 out-of-hospital SCA presumed to be cardiac in nature that occurred over the six years, 74 were identified as occurring during or within one hour of sports activities (16 during competitive sports, 58 during recreational sports). Although the overall rate of SCA in athletes was 0.76 per 100,000 athlete-years, 44 percent survived to hospital discharge, leading to an overall rate of SCD of 0.42 per 100,000 athlete-years. The incidence rate was somewhat higher among athletes ages 12 to 17 years (SCA rate 1.17 per 100,000 athlete-years; SCD rate 0.65 per 100,000 athlete-years) but still lower than prior SCD estimates of 1:50,000 athletes per year.
The magnitude of the problem and the challenges inherent in screening are illustrated in reports of arrhythmic events associated with major endurance sporting events [8,11]. As an example, in a study examining SCD in 215,413 marathon runners participating in one of two marathons over a 19-year period, the following findings were noted :
●SCD occurred in four individuals during or immediately following the marathon, an incidence of approximately 1 in 50,000. This is substantially lower than the annual risk of premature death in the general population.
●None of the four subjects had prior cardiac symptoms.
●Two of the four had completed several previous marathons.
●Three of the four had coronary artery disease on autopsy, although none had a previous infarction.
Although the incidence of SCD among marathon runners is low (one death per 215,000 hours), it is higher than for other types of exercise, such as noncompetitive jogging (one death per 396,000 hours), cross-country skiing (one death per 607,000 hours), or general, noncompetitive exercise (one death per 375,000 hours) [12-15].
ETIOLOGY OF SUDDEN DEATH
Structural heart disease — SCD in athletes often occurs in the presence of structural heart disease, although the underlying disorder is usually undetected until the presenting arrhythmic event. Structural heart disease can increase the risk for SCD by one or more of the following mechanisms:
●By far the most frequent mechanisms are ventricular tachyarrhythmias, which are commonly due to reentrant arrhythmias that develop in abnormal myocardium and/or areas of fibrotic replacement of myocardial tissue.
●Other rare but possible mechanisms include bradyarrhythmia or asystole due to extension of the pathologic process into the conduction system, causing complete heart block without a reliable escape focus.
●Syncope, in addition to arrhythmic causes, may result from outflow tract obstruction in hypertrophic cardiomyopathy and aortic stenosis, as well as from cyanosis during exercise in the setting of certain congenital lesions with right-to-left shunts.
●Dissection of the great vessels, as in patients with Marfan syndrome.
Athletes <35 years of age — Several large series have evaluated SCD in athletes less than 35 years of age [6,16-24] . In most cases, structural heart disease was present, although more contemporary data suggest more sudden arrhythmic death with a structural normal heart [2,22]. When present, the most common structural heart diseases include hypertrophic cardiomyopathy (HCM), anomalous origin of a coronary artery, arrhythmogenic right ventricular cardiomyopathy (ARVC, which commonly also affects the left ventricle), myocarditis, and coronary atherosclerosis, albeit with some variation among the different series.
●Among 1435 young competitive athletes from a United States registry in whom cardiovascular disease was evident on postmortem examination following SCD, HCM (36 percent) and anomalous origin of a coronary artery accounted for more than half of the cases . A separate study showed that among 51 middle school athletes, anomalous origins of a coronary artery accounted for one-third of cases of sudden cardiac arrest and death . However, among 55 college and professional athletes, cardiomyopathies (hypertrophic, arrhythmogenic, dilated, noncompaction, or restrictive) accounted for nearly half of cases.
●In a cohort of over six million military recruits in the United States (mean age 19, range 17 to 35), among whom 126 nontraumatic sudden deaths occurred (including 108 [86 percent] related to exercise), anomalous origin of a coronary artery (33 percent), myocarditis (20 percent), coronary atherosclerosis (16 percent), and HCM (13 percent) accounted for over three-quarters of the structural abnormalities .
●In a series from the United Kingdom Regional Registry of 357 consecutive athletes with SCD between 1994 and 2014 (mean age 29 years), sudden arrhythmic death syndrome (SADS), likely including undiagnosed primary electrical disease, was the most prevalent cause of death (42 percent) . Myocardial disease was detected in 40 percent of cases, including idiopathic left ventricular (LV) hypertrophy and/or fibrosis (16 percent), ARVC (13 percent), and HCM (6 percent).
●A different distribution was noted in a series of 49 athletes under age 35 with SCD from northern Italy . In this series, ARVC (22 percent) was the most common abnormality, followed by coronary atherosclerosis (18 percent) and anomalous origin of a coronary artery (12 percent).
Athletes ≥35 years of age — In contrast to these series in young subjects, among those ≥35 years of age (so-called masters athletes), coronary artery disease is the predominant cause of SCD during exercise [23,26]. (See 'Coronary artery disease' below.)
Primary electrical disease — SCD during athletics also occurs in the absence of structural heart disease, a situation termed primary electrical disease. Series of patients with SCD have shown an increasing number with normal autopsies, although there is concern that cardiac abnormalities may have been missed. A number of inherited arrhythmic syndromes predispose individuals to SCD, and the heart is usually structurally normal in these patients. Examples include:
●Long QT syndrome (see "Congenital long QT syndrome: Epidemiology and clinical manifestations")
●Brugada syndrome (see "Brugada syndrome: Clinical presentation, diagnosis, and evaluation")
●Catecholaminergic polymorphic ventricular tachycardia (see "Catecholaminergic polymorphic ventricular tachycardia")
●Short QT syndrome (see "Short QT syndrome")
●Early repolarization syndrome (see 'Early repolarization syndrome' below)
In addition, in individuals with structurally normal hearts, arrhythmic events may be precipitated by trauma or occur as sporadic/idiopathic phenomena, such as commotio cordis, in which SCD results from being struck in the precordium with a projectile object such as a baseball, hockey puck, or fist. (See "Commotio cordis".)
Finally, several case reports describe SCD in young athletes who had no previously known heart disease but were taking androgens for performance enhancement; cardiac hypertrophy or myocarditis were found at autopsy [27,28]. It is not possible to establish causality in these sporadic cases. (See "Use of androgens and other hormones by athletes", section on 'Side effects and complications'.)
STRUCTURAL ABNORMALITIES ASSOCIATED WITH SCD
Hypertrophic cardiomyopathy — Our experts agree that a tailored exercise program can and should be regularly performed by most individuals with hypertrophic cardiomyopathy (HCM).
Historically, persons with a probable or unequivocal clinical diagnosis of HCM have been advised not to participate in most competitive sports with the possible exception of those sports that are at low intensity (figure 1) [29,30].
A novel and less restrictive approach has been suggested by the 2020 European Society of Cardiology (ESC) sport cardiology guidelines . The guidelines include the option for selective participation in recreational and competitive athletic activity in patients with HCM who have a low-risk profile (ie, without any risk factors that would place them at high risk for SCD), provided that they undergo periodic evaluation. The 2020 ESC guidelines confirm that patients with high-risk markers should not participate in competitive athletics. The 2020 American Heart Association/American College of Cardiology (AHA/ACC) HCM guidelines allow for a shared decision-making approach for patients with HCM, in which the clinician and the athlete share discussion of the potential risks and benefits of exercise .
Activity advice in patients with HCM has been based largely on expert opinion given limited data. Some moderate-intensity and many low-intensity recreational activities were generally considered to be safe when performed in moderation, including biking, doubles tennis, swimming laps, golf, and skating, and should be considered on a case-by-case basis [31,33]. Lifting weights with weight-training machines may be safe, but intense static (isometric) activity were discouraged because of the possible induction of a Valsalva maneuver and exacerbation of an LV outflow tract gradient.
HCM is a relatively common disease, occurring in approximately 1 out of 500 individuals in the general population. In most athletes with SCD due to HCM, the diagnosis of HCM was not previously established. Patients with HCM who are at the highest risk of SCD are those with prior sudden cardiac arrest. In addition, those with unexplained syncope, massive hypertrophy (maximum LV wall thickness >30 mm), family history of SCD due to HCM, significant LV outflow tract obstruction (gradient >50 mmHg), nonsustained ventricular tachyarrhythmias observed on electrocardiogram (ECG) monitoring, including exercise-related VT, apical aneurysms, and extensive scarring on cardiovascular magnetic resonance imaging are at increased risk . Moreover, age is a relevant determinant, with adolescent and young athletes being at higher risk than adult patients. Among patients with HCM, stratification as advised by the AHA and the ESC can identify patients at high and relatively low risk for SCD; however, zero risk does not exist and even patients defined as low risk have a small but nontrivial risk of SCD [34-36]. (See 'Etiology of sudden death' above and "Hypertrophic cardiomyopathy: Risk stratification for sudden cardiac death".)
Some data suggest a relatively low risk of ventricular arrhythmias and SCD in athletes with HCM regardless of the continuation or discontinuation of training and competition. In a cohort of 88 Italian athletes with HCM who were advised to discontinue training and competition (77 who were low risk by the ESC algorithm, 67 who were low risk by the AHA algorithm), 61 patients stopped exercising, but 27 continued to exercise against clinician advice . Over an average follow-up of seven years, 1.3 percent of patients per year developed symptoms (syncope, palpitations), and only one cardiac arrest occurred (in a detrained patient and not during exercise), with no significant difference in the event rates between the sedentary and exercising groups. (See "Hypertrophic cardiomyopathy: Risk stratification for sudden cardiac death".)
The natural history is not well defined in individuals with a genetic diagnosis of HCM in the absence of symptoms and phenotypic expression (ie, without LV hypertrophy) of the disease (so-called genotype positive, phenotype negative carriers). At present, no compelling data are available that would preclude these patients from competitive sports, particularly in the absence of a family history of sudden death . Professional societies, and our experts, agree that these individuals should have periodical clinical and imaging follow-up (annually during adolescence and eventually every two years in adulthood) [1,31,39].
Congenital coronary artery abnormalities — Patients with any uncorrected anomalous coronary artery origin, regardless of the presence or absence of symptoms, are generally advised against participation in competitive sports . These patients may be considered for appropriate management, which in selected cases may include surgical correction (ie, coronary artery reimplantation). Participation in sports at least three months after successful operation may be considered on an individual basis for an athlete without prior infarction and in the absence of ischemia, ventricular tachyarrhythmia, or LV dysfunction during maximal exercise testing . Athletes with previously infarcted myocardium need to follow appropriate guidelines for clearance and observation, which primarily depend upon the degree of LV dysfunction and exercise-associated arrhythmias. In such patients, the approach is similar to that in patients with atherosclerotic coronary artery disease . (See 'Coronary artery disease' below and "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease" and "Cardiac rehabilitation programs".)
Anomalous origin of a coronary artery is found in 12 to 33 percent of young athletes with SCD at autopsy [16,25,42]. The most common anomalies associated with SCD are the origin of the left main coronary artery from the right sinus of Valsalva and the origin of the right coronary artery from the left coronary sinus [43-46]. (See 'Etiology of sudden death' above and "Congenital and pediatric coronary artery abnormalities", section on 'Variations of coronary artery origin from the aorta'.)
High-risk coronary anomalies are those in which the anomalous coronary artery originates with a slit-like ostium, has proximal intramural course, makes an acute bend, and courses between the pulmonary artery and aorta [43,46]. The presumed mechanism of SCD involves repeated bouts of silent ischemia secondary to an exaggeration of a sharp angle in the aberrant origin that occurs with exercise, with decreased blood flow in the intramural course and/or in the interarterial course between an expanded aorta and pulmonary arterial trunk. Chronic ischemia is considered responsible for myocardial fibrosis representing the ultimate substrate for induction of tachyarrhythmias during exercise.
Patients with congenital coronary anomalies may present with syncope or presyncope, especially with exercise and with angina in a limited proportion of cases. Unfortunately, SCD is often the first clinical symptom. This was illustrated in a report of 18 patients with an anomalous coronary artery origin, only six of whom had a preceding history of angina and/or syncope . In another series of autopsy results on 27 patients with an anomalous coronary artery, 55 percent had no clinical manifestations during life or with testing . In the remaining patients, premonitory symptoms occurred only shortly before SCD.
Physical examination and diagnostic studies are usually unrevealing in the absence of myocardial infarction (MI) or symptoms of ongoing ischemia. When anomalous origin of a coronary artery is suspected (usually by echocardiography), noninvasive computed tomography coronary angiography (CTCA) is advised to define anomalous coronary anatomy. Cardiovascular magnetic resonance imaging (CMR) is a noninvasive alternative to CTCA and can include gadolinium contrast imaging for identification of intramyocardial late gadolinium enhancement (LGE). Coronary angiography had been the historical gold standard for the evaluation of the origin and course of the coronary arteries and is still recommended when other studies are not diagnostic . (See "Congenital and pediatric coronary artery abnormalities", section on 'Variations of coronary artery origin from the aorta' and "Cardiac imaging with computed tomography and magnetic resonance in the adult".)
Arrhythmogenic (right and/or left) ventricular cardiomyopathy — Because of the evidence linking athletic participation with worsened outcomes, patients with arrhythmogenic right/left ventricular cardiomyopathy (AC) should not participate in competitive sports (figure 1) [29-31]. Similarly, patients with AC should not participate in high-intensity noncompetitive sports, including basketball, ice hockey, sprinting, and singles tennis [29-31]. In addition, the risks associated with impaired consciousness (ie, syncope or presyncope) should be considered with regard to activities with the potential for trauma (eg, weight training with free weights, horseback riding) or certain water activities (eg, scuba diving or snorkeling). Patients with AC are also advised to avoid most moderate-intensity amateur activities, including biking and doubles tennis. However, it has been shown that low-intensity exercise programs have no tangible negative impact on the natural course of AC and, therefore, they may participate in low-intensity recreational activities (class IA), including golf, skating, and light weightlifting (with weight-training machines). (See "Arrhythmogenic right ventricular cardiomyopathy: Treatment and prognosis".)
The condition was initially recognized as a predominantly right ventricular (RV) disease involving fibro-fatty or fibrous infiltration of predominantly the free wall, known as arrhythmogenic RV cardiomyopathy (ARVC). However, it is now well established that in the majority of cases both ventricles are affected, and in some it may only affect the LV. The diagnosis of ARVC is based on task force criteria that encompass electrophysiological, anatomical, functional, and clinical features of the disease .
Tachyarrhythmias and SCD are as frequent in patients with AC compared with those with a dilated cardiomyopathy or a previous infarction [16,49]. In a cohort of patients with AC followed for over 10 years, the mortality rate was 20 percent . AC is a significantly more common cause of SCD in case series from Italy than in those from the United States [16,42]. (See 'Etiology of sudden death' above.)
The clinical presentation of patients with AC, particularly the athlete, includes exercise-induced palpitations, presyncope, and/or syncope, consistent with the catecholamine-sensitive nature of many of the associated tachyarrhythmias, as well as the wall stretch observed in the right (and left) heart in response to the increased venous return occurring with exercise . The diagnostic evaluation of AC is discussed separately. (See "Arrhythmogenic right ventricular cardiomyopathy: Diagnostic evaluation and diagnosis".)
Among a cohort of 108 patients with AC that included 41 competitive athletes, 48 recreational athletes, and 19 inactive patients, the risk of VT or SCD was significantly higher among competitive athletes compared with either recreational athletes (hazard ratio [HR] 2.0, 95% CI 1.2-3.3) or inactive patients (HR 2.1, 95% CI 1.1-3.9) . In addition, there are increasing data that repetitive extreme conditioning/exertion enhances disease progression [52,53]. Any activity, competitive or not, that causes symptoms of palpitations, presyncope, or syncope should be avoided.
Marfan syndrome — Athletes with Marfan syndrome can selectively participate in low and moderate static/low dynamic competitive sports (classes IA and IIA) (figure 1) if they do not have one or more of the following: aortic root dilatation, moderate-to-severe mitral regurgitation, or family history of dissection or sudden death in a Marfan relative . These athletes should have an echocardiographic measurement of aortic root dimension repeated every 6 to 12 months (depending upon the size of the aorta, rate of growth, etc) for close surveillance of aortic enlargement. (See "Management of Marfan syndrome and related disorders", section on 'Monitoring MFS'.)
Athletes with Marfan syndrome, familial aortic aneurysm or dissection, or congenital bicuspid aortic valve with any degree of ascending aortic enlargement should not participate in sports that involve the potential for bodily collision. On the other hand, some moderate-intensity and many low-intensity recreational activities are generally considered to be safe, including stationary biking, hiking, doubles tennis, swimming laps, golf, and skating. However, intense static (isometric) exertion is associated with increased wall stress; therefore, activities such as weight training with either free weights or weight machines should be avoided.
Marfan syndrome is an autosomal dominant condition that is one of the most common inherited disorders of connective tissue. The full phenotype is characterized by arachnodactyly, tall stature, pectus excavatum, kyphoscoliosis, and lenticular dislocation. Malignant arrhythmias are not common in Marfan syndrome, but the cardiovascular manifestations include aortic dissection, which can lead to sudden death. The genetics, epidemiology, diagnosis, and management of Marfan syndrome are discussed in detail separately. (See "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders" and "Management of Marfan syndrome and related disorders".)
Myocarditis — Persons with probable or definite evidence of myocarditis should be withdrawn from all competitive and recreational sports and undergo a prudent convalescent period of between three and six months following the onset of clinical manifestations [29,31].
Athletes may return to training and competition after this period of time if LV systolic function has returned to normal (based on echocardiography and/or CMR), clinically relevant arrhythmias such as frequent and/or complex repetitive forms of ventricular or supraventricular ectopic activity are absent on ambulatory Holter monitoring and graded exercise testing, and serum markers of inflammation and heart failure have normalized. The impact that persistent LGE on CMR represents following the apparent clinical resolution of myocarditis is still uncertain . As patients with previous myocarditis are at increased risk of recurrence and/or silent progressive myocardial dysfunction, periodic clinical reevaluation (at least annually) is recommended, including clinical assessment and imaging testing . Patients should be advised to seek medical attention for dyspnea on exertion, syncope, or arrhythmic events.
The clinical presentation of myocarditis is quite broad, from subclinical cases with only mild reduction of physical performance or palpitation to more severe presentations with clinical findings of heart failure in an otherwise healthy young person. The ECG usually shows diffuse repolarization abnormalities, and global or regional wall motion abnormalities are present on cardiac imaging. Active myocarditis is associated with atrial and ventricular tachyarrhythmias, bradyarrhythmias, and SCD. Healed myocarditis leading to a dilated cardiomyopathy or persistent segmental abnormalities increases the risk of SCD, and this risk may be proportional to the degree of cardiac dysfunction and severity of clinical presentation. (See "Clinical manifestations and diagnosis of myocarditis in adults".)
Myocarditis and other causes of myocardial injury in individuals with coronavirus disease 2019 (COVID-19), the risk of SARS-CoV-2 vaccine-associated myocarditis, and return to play after COVID-19 are discussed separately. (See "COVID-19: Cardiac manifestations in adults" and "COVID-19: Evaluation and management of cardiac disease in adults" and "COVID-19: Arrhythmias and conduction system disease" and "COVID-19: Vaccines", section on 'Myocarditis' and "COVID-19: Return to sport or strenuous activity following infection".)
Congenital heart diseases — The estimated prevalence of congenital abnormalities in the athlete is 0.2 percent. Recommendations for athletic activity in patients with congenital heart disease, which are based primarily on expert opinion, depend upon the nature of the abnormality . The approach for exercise prescription in adolescents and adults with congenital heart disease should be individualized .
However, there is generally a prohibition of competitive sports in those who have:
●Significant pulmonary hypertension
●Cyanosis with an arterial saturation <80 percent
●Symptomatic ventricular dysfunction
INHERITED ARRHYTHMIA SYNDROMES — There is a partial divergence of opinions on competitive athletics for individuals with inherited arrhythmias, and specifically for long QT syndrome (LQTS) [56-59]. The 2015 American Heart Association/American College of Cardiology (AHA/ACC) Scientific Statement on Eligibility and Disqualification Recommendations for Competitive Athletes discusses participation in competitive events and training sessions in patients with channelopathies (namely, LQTS) as allowable if the patient is asymptomatic and an emergency action plan with an automated external defibrillator (AED) is immediately available on site. However, a different approach is dictated by the European guidelines, which advise precautionary restriction from competitive sports in patients with a pathologic genetic mutation and full phenotype expression.
Congenital long QT syndrome — Guidelines for physical activity and sports participation in congenital LQTS are presented separately. (See "Congenital long QT syndrome: Treatment", section on 'Physical activity and LQTS'.)
Brugada syndrome — Professional society guidelines allow sports participation in patients with Brugada syndrome who are defined as low risk based on absence of symptoms and events after the clinician and patient participate in a fully informed discussion and shared decision-making process and take all appropriate precautionary measures .
In contrast to other inherited arrhythmia syndromes, most moderate- and low-intensity recreational, noncompetitive sports are considered safe for patients with Brugada syndrome or Brugada pattern ECG, except for those that would incur significant risk of trauma with impaired consciousness should syncope or presyncope result (eg, weightlifting with free weights, horseback riding, motor races, downhill skiing, scuba diving, or snorkeling). Moreover, patients should avoid triggering drugs , electrolyte imbalance, and increases in core temperature >39°C (eg, by avoiding saunas, steam rooms, and sports in warm/humid conditions, including prolonged endurance events such as marathons in unfavorable atmospheric conditions).
Patients with Brugada syndrome have historically been advised to avoid most high-intensity competitive sports, including cycling, rowing, basketball, ice hockey, sprinting, and singles tennis. However, there is no evidence that exercise in patients with Brugada syndrome increases the risk of cardiac arrest.
Brugada syndrome is characterized by the ECG findings of right bundle branch block (RBBB) pattern and ST-segment elevation in leads V1 to V3 (waveform 1), and an increased risk of sudden death. Arrhythmic events generally occur between the ages of 22 and 65 and are more common at night than in the day and during sleep than while awake [61,62]. SCD in Brugada patients is usually not related to exercise . (See "Brugada syndrome: Clinical presentation, diagnosis, and evaluation".)
Catecholaminergic polymorphic ventricular tachycardia — We agree with professional society recommendations that patients with catecholaminergic polymorphic VT (CPVT) who were previously symptomatic, and asymptomatic patients with exercise-induced ventricular premature beats in a pattern of bigeminy, couplets, or nonsustained VT, should be restricted from competitive sports with the exception of minimal contact, class IA activities (figure 1) .
Among individuals with a genetic diagnosis of CPVT, but who remain asymptomatic with none of the clinical features of inducible VT (so-called genotype positive, phenotype negative patients), the natural history is not well defined. As such, no agreement exists in the guidelines, and specifically, a prudent precautionary restriction from competitive sports is advised by European recommendations with more uncertainty in the AHA/ACC Guidelines.
CPVT occurs in the absence of structural heart disease or known associated syndromes. The disorder typically begins in childhood or adolescence, and affected patients may have a family history of juvenile sudden death or stress-induced syncope . The disorder has been linked to mutations in the cardiac ryanodine receptor and calsequestrin 2 genes. (See "Catecholaminergic polymorphic ventricular tachycardia".)
Affected patients present with life-threatening VT or ventricular fibrillation (VF) occurring during emotional or physical stress, with syncope often being the first manifestation of the disease . Arrhythmic events during swimming, previously considered to be specific for LQTS type 1, have also been described with CPVT . The VT may have a polymorphic appearance or may be a bidirectional VT that resembles the arrhythmia associated with digitalis toxicity.
Short QT syndrome — Short QT syndrome is an extremely rare inherited channelopathy associated with marked shortened QT intervals and SCD in individuals with a structurally normal heart. Based on expert opinion, short QT syndrome is managed similarly to other inherited arrhythmia syndromes (ie, LQTS), although there is a paucity of data regarding the risks of exercise in this condition. (See 'Inherited arrhythmia syndromes' above.)
When an abnormally short QTc interval is identified in an athlete (QTc <320 milliseconds), causes of transient QT shortening (such as hypercalcemia, hyperkalemia, hyperthermia, acidosis, and some drugs [eg, digitalis, anabolic steroids]) must be ruled out. In the absence of acquired causes of short QT interval, the athlete may be referred for familial ECG clinical screening and molecular genetic evaluation. However, the limited specificity of a short QTc must be acknowledged; the vast majority of patients with a short QTc will not have the syndrome. The clinical features and management of short QT syndrome are discussed in detail separately. (See "Short QT syndrome".)
Early repolarization syndrome — The early repolarization syndrome is the combination of early repolarization pattern and arrhythmic symptoms and/or SCD, not just early repolarization pattern. At present, no data are available regarding the impact of regular exercise programs and sports participation on the natural outcome of the early repolarization syndrome, and a prudent precautionary attitude is advised.
The term early repolarization has long been used to characterize a QRS-T variant with J-point elevation on the ECG. Two terms, distinguished by the presence or absence of symptomatic arrhythmias, have been used to describe patients with this ECG finding: the early repolarization pattern describes the patient with appropriate ECG findings in the absence of symptomatic arrhythmias, while the early repolarization syndrome applies to the patient with both appropriate ECG findings and symptomatic ventricular arrhythmias, typically VF. Recommendations regarding participation in athletics apply only to patients with the early repolarization syndrome. (See "Early repolarization".)
Early repolarization pattern, meaning the presence of ST-segment elevation in precordial leads, usually preceded by J-point elevation, is a common finding in athletes and is associated with other typical features of the athlete's ECG, such as bradycardia, increased R/S wave voltages, and incomplete RBBB. Typically, early repolarization in athletes disappears during exercise. This ECG pattern is not associated with symptoms or family history of SCD and does not require additional testing for diagnosis. There are no sports restrictions for these individuals.
CORONARY ARTERY DISEASE
Our approach to participation — Patients with clinically proven coronary artery disease (CAD) who are considered to be at low-risk for cardiac events after individual evaluation may be allowed to participate in competitive sports. As a measure of caution, in consideration of the high hemodynamic load and possible electrolyte imbalance, some restrictions may apply on an individual basis for sports with the highest cardiovascular demand, such as extreme power and endurance disciplines.
Patients with clinically proven CAD who are considered to be at high risk should be temporarily restricted from competitive sports and receive appropriate management. In situations where full medical therapy has been implemented and persistent ischemia remains, revascularization may be considered on a case-by-case basis. After revascularization, the individual patient should be encouraged to start exercise programs without delay, as per the cardiac rehabilitation guidelines. In the early phase, exercise should be prescribed in a graduated fashion, starting with low-intensity exercise of limited duration and progressively increased. When the clinical situation is stable and the patient is asymptomatic, a more intense training and participation in competition should be considered after a graduated and progressive increase in rehabilitation training load.
We recommend a minimum of three months after percutaneous coronary intervention before participation in competitive sports can be resumed. Participation in competitive sports may be selectively advised as per patients with CAD and well-treated risk factors if exercise is not associated with elements of high risk, such as critical coronary artery stenosis (>70 percent), LV dysfunction, inducible ischemia by exercise, or frequent, repetitive ventricular arrhythmias induced by exercise. Contact sports should be avoided while the patient is under dual antiplatelet therapy because of the risk of bleeding, but may be considered afterwards. (See "Cardiac rehabilitation: Indications, efficacy, and safety in patients with coronary heart disease".)
In patients ≥35 years of age, the most frequent cause of exercise-related SCD is CAD. Ventricular arrhythmias can originate from myocardial scar (from prior MIs), or from acute ischemia. In addition, ischemia during exertion can result either from fixed, chronic coronary stenosis that precludes increased myocardial oxygen delivery during exercise (ie, demand ischemia), or from an acute coronary syndrome. Autopsy examination of adults with exercise-related SCD usually reveals advanced CAD and/or an acute coronary lesion . (See "Pathophysiology and etiology of sudden cardiac arrest" and "Mechanisms of acute coronary syndromes related to atherosclerosis".)
Risk assessment — Prior to initiating systematic training or competition, athletes with previously documented CAD should have an assessment of LV function. Universal exercise testing is somewhat controversial, although many clinicians state it should be performed, both to assess exercise capacity to determine the possible induction of signs of ischemia and to ensure the absence of exercise-induced arrhythmias. Whenever possible, such testing should be performed while the patient is taking prescribed medications and should approximate the cardiovascular and metabolic demands of the planned athletic activity. The approach to screening is discussed in detail separately. (See "Screening to prevent sudden cardiac death in competitive athletes".)
There are no data that directly relate the presence and severity of CAD to the risk of participating in competitive athletics. However, it is likely that the risk of a cardiac event during exercise increases with the presence of increasingly severe CAD, type of lesion (soft plaques are at higher risk of rupture), LV dysfunction, and ventricular arrhythmias, as well as with the intensity of the competitive sport and the individual's effort. As a result, risk assessment should involve a full evaluation of cardiac status in individual patients.
Athletes with CAD are considered to be at low risk if all of the following are true :
●LV ejection fraction ≥50 percent.
●Normal exercise tolerance for age. (See "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease", section on 'Benefits of fitness'.)
●No inducible ischemia with exercise testing. (See "Prognostic features of stress testing in patients with known or suspected coronary disease".)
●No sustained or nonsustained VT during exercise testing.
●No hemodynamically significant coronary artery stenosis (ie, no stenosis ≥70 percent in a major coronary artery and no stenosis ≥50 percent in the left main coronary artery) if coronary artery tomography or coronary angiography is performed. Patients who have had successful revascularization of prior stenosis are also considered to be at low risk.
SUMMARY AND RECOMMENDATIONS
●Competitive versus recreational athletics – The balance between the risks and benefits of athletic activity depends upon several factors, including baseline fitness level, the nature and intensity of athletic activity, the presence and extent of cardiac disease, and the psychologic and physical benefit from sport. Although there are exceptions, for most individuals, the overall benefits of regular exercise far outweigh the risks. (See 'Competitive versus recreational athletics' above.)
●Incidence of sudden cardiac death – The incidence of SCD among young athletes is actually quite low, estimated to be between 1:50,000 and 1:100,000 young athletes per year. This rate is notably higher in older adults, closer to 1:7000 healthy adult athletes per year. (See 'Incidence of sudden cardiac death' above.)
●Etiology and pathophysiology of sudden death – The potential etiologies of SCD include certain structural heart diseases, inherited arrhythmia syndromes, and coronary heart disease; the exact distribution of etiologies varies according to age and geography. (See 'Etiology of sudden death' above and "Pathophysiology and etiology of sudden cardiac arrest".)
●Activity restriction – Some level of activity restriction (figure 1) is recommended for nearly all individuals with underlying heart disease. The precise restrictions vary depending on the underlying disease process and other comorbidities. (See 'Structural abnormalities associated with SCD' above and 'Inherited arrhythmia syndromes' above and 'Coronary artery disease' above.)
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