Introduction
Regular exercise has many favorable effects on the cardiovascular system. However,
intense physical activity, especially in a competitive fashion, may become hazardous
to genetically vulnerable individuals.
A competitive athlete is one who participates in an organized team or individual sport
that requires regular competition against others as a central component, places a
high premium on excellence and achievement, and requires some form of systematic (and
usually intense) training. Soccer, basketball, running, cycling, and swimming are
some examples of competitive sports with high dynamic activity, whereas gymnastics,
weight lifting, and sailing are examples of competitive sports with high static activity.
Sudden cardiac death (SCD) in sports and exercise is defined as cardiac arrest occurring
during or within 1 hour of exercise or sports-related activity, and genetically transmitted
cardiovascular diseases are among the most common pathologies leading to SCD in competitive
athletes (1).
Sudden death of a competitive athlete has a mass and undesirable effect on the community.
Properly diagnosing inherited cardiovascular pathologies, making appropriate recommendations
on physical activity in athletic population, and providing close supervision to diseased
athletes are the main duties of cardiovascular specialists.
The aim of our document is to summarize the various aspects of the most common genetic
cardiovascular diseases in athletes and to make recommendations for diseased athletes
and athletes with implanted cardiac pacemakers/Implantable Cardioverter Defibrillators
(ICDs) based on the current literature. Our general recommendations are summarized
in Figure 1 and discussed below in detail.
Figure 1
Athletic activity recommendations for athletes with genetic cardiovascular pathologies
and commotio cordis
For Athletic activity boxes; Red box: Athletic activity prohibited. Yellow box: Athletic
activity allowed selectively according to the level of activity and athlete’s condition.
Green box: All athletic activities allowed. ARVC - arrythmogenic right ventricular
cardiomyopathy, CAAs - coronary artery anomalies, DCM - dilated cardiomyopathy, HCM
- hypertrophic cardiomyopathy, LVNC - left ventricular non compaction, WPW - Wolf
Parkinson White syndrome
The incidence of SCD in athletic population varies between 0.5 and 13 deaths per 100.000
athletes according to current literature (2, 3).
The most common genetic cardiovascular diseases which leads to SCD varies among different
regions of the world. In the United States (US), hypertrophic cardiomyopathy (HCM)
is responsible for one-third of the mortality in the athletic population and congenital
coronary anomalies is the second in frequency (4). In the Veneto region of Italy,
arrhytmogenic right ventricular cardiomyopathy (ARVC) has been reported as the most
common cause of SCD in young athletes (5). Another study which investigated the causative
pathologies of SCD in athletes with detailed post mortem evaluation found that idiopathic
left ventricular hypertrophy/fibrosis and ARVC were the most common causes of SCD
in athletes (6). The etiology of SCD in competitive athletes involves a wide range
of pathologies as listed in Table 1 and discussed below.
Table 1
Etiology of sudden cardiac death in competitive athletes
•
Cardiomyopathies
○
Hypertrophic cardiomyopathy
○
Non-compaction cardiomyopathy
○
Dilated cardiomyopathy
◾
Myocarditis
○
Arrythmogenic right ventricular cardiomyopathy
•
Commotio cordis
•
Coronary artery anomalies
•
Channelopaties
○
Long QT syndrome
○
Short QT syndrome
○
Brugada syndrome
○
Catecholaminergic polymorphic ventricular tachycardia
○
Early repolarization syndrome
•
Wolf Parkinson White syndrome
•
Idiopathic left ventricular hypertrophy/fibrosis
•
Coronary atherosclerosis
Cardiomyopathies
Hypertrophic cardiomyopathy
HCM is an inherited disorder defined by the presence of increased left ventricular
(LV) wall thickness that cannot be explained by abnormal loading conditions of a cardiac
or a systemic disease. LV wall thickness of ≥15 mm in at least one segment measured
by an imaging technique is required for the definite diagnosis of HCM (7). Since HCM
has been accepted as one of the major pathology that leads to SCD in young athletes
(4, 8), it is of paramount importance to detect the disease before athletic participation
to make the distinction between HCM and physiological hypertrophy and manage patients
during the sporting activity.
Main abnormalities on electrocardiography (ECG) of athletes with HCM are large QRS
voltages, T wave inversion, ST depression, and pathological Q waves. On echocardiographic
examination, most athletes with HCM had larger LV cavity dimensions with lesser LV
hypertrophy and better indices of diastolic function compared to non-athletic HCM
patients. The pattern of LV hypertrophy in athletes with HCM is mostly asymmetric
and focal in contrast to the symetrical pattern of physiological LV hypertrophy of
the athlete’s heart. Apical hypertrophy is also seen in a substantial number of athletes
with HCM. Healthy athletes show 10%–20% increase in LV wall thickness. LV wall thickness
of 13–16 mm falls into a “gray zone”, and more clinical and imaging data is required
to differentiate an athlete’s heart from HCM. Non-sustained ventricular tachycardia
(VT) on Holter ECG, late gadolinium enhancement (LGE) in cardiac magnetic resonance
imaging (MRI), and genetic testing further help establish the diagnosis of HCM and
discriminate the pathologic condition from the athlete’s heart (9).
Although vigorious physical activity is restricted, the relationship between athletic
activities and SCD in HCM is not fully understood. Population based studies showed
that the majority of SCDs of HCM patients occurred during routine daily activities
and rest or sleep (10, 11). A recently published study examined 35 athletes with a
definite diagnosis of HCM. The majority of the athletes had a low risk profile. During
9 years of follow-up, the incidence of events and symptoms was not different between
athletes who continued to exercise and who quit to exercise (12).
Exercise recommendations for athletes with HCM could be challenging. In recent years,
trials which investigate the effect of supervised exercise training on patients with
HCM found positive effects of exercise on peak oxygen consumption without serious
adverse effects (13). In addition, observational studies conducted on athletes with
HCM found that high intensity exercise had positive effects on structural and functional
cardiac parameters (9, 14).
Patients with HCM are advised to restrict participation in athletic activities according
to the AHA/ACC task force report which was published in 2015 (10). The latest ESC
report stated that participation in intensive exercise programs and competitive sport
should be considered on an individual basis. After full evaluation of the disease
characteristics and risk determinants, patients with HCM who have high-risk clinical
characteristics must be withheld from athletic activities (15). It is of paramount
importance to discriminate the ones who have high-risk features of HCM when restricting
athletes from competitive activities.
Non-compaction cardiomyopathy
Left ventricular non-compaction (LVNC) is a genetic cardiomyopathy which is characterized
by prominent myocardial trabeculations and deep intertrabecular recesses associated
with LV dysfunction. Heart failure symptoms, syncope, systemic thromboembolism, and
VT are the main clinical presentations of the patients with LVNC (16). The main symptom
was found to be syncope without prodromal symptoms during activity in athletes with
LVNC (17). Although LVNC is rarely seen in athletes and accounts for the minority
of SCDs in athletic cohorts, differentiating the morphological alterations of LVNC
from the adaptive changes of an athlete’s heart is an important issue. There is no
specific ECG finding for LVNC. LV hypertrophy, repolarization abnormalities, and QT
prolongation were found to be the most common abnormalities on ECG (18). Sustained
VT can also be seen in athletes with LVNC (17). Several echocardiographic criteria
were identified for making the diagnosis of LVNC. The main findings on echocardiography
are ≥2 ratio of non-compacted/compacted layer, presence of deep intertrabecular recesses
filling with ventricular blood and numerous trabeculations protruding from LV wall
with reduced ejection fraction (<50%) (16).
A study which compared the echocardiographic results of elite athletes with normal
population and LVNC patients found that 20% of the athlete group expressed an increased
number of LV trabeculation and 10% of the athletes had fullfilled the conventional
echocardiographic criteria of LVNC. Authors stated that this may not be the true incidence
of the disease and more stringent criteria for the diagnostic consideration of LVNC
are required in this special population (19). According to another study, prominent
LV trabeculation was found only in 1.4% of a large athlete population. Although 66%
of the athletes who had LV hypertrabeculation match the echocardiographic criteria
for LVNC, none of them had LV dysfunction, positive family history, pathologic cardiac
MRI findings, and symptoms (20). Thus, athletes with hypertrabeculation have to be
evaluated carefully and should not be diagnosed directly as LVNC. However, athletes
with symptoms and/or high-risk clinical features should be restricted from the athletic
activities.
Dilated cardiomyopathy
Dilated cardiomyopathy (DCM) is a myocardial disease characterized by dilated and
hypokinetic LV with or without right ventricle dysfunction. Dilated cardiomyopathy
may be idiopathic or originating from infection, inflammation, toxic agents or ischemia
(21). Occasionally, DCM is a known cause of SCD in athletes (2, 3).
The ECG may be normal or exhibit similar changes to those of athletic individuals
such as atrial dilatation, axis deviation or large QRS voltages, and T wave inversion
in lateral leads.
Consensus statements
Recommendations
References
Hypertrophic cardiomyopathy
Athletes with HCM who are asymptomatic and do not have significant LVOT gradient could
be supervised closely and may selectively participate in athletic activities.
10, 15
Athletes with HCM who have a history of aborted SCD, exercise-induced ventricular
tachycardia, unexplained syncope, significant LVOT gradient, and abnormal blood pressure
response to exercise have to be restricted from athletic acitivities.
10, 15
Genotype positive phenotype negative asymptomatic HCM patients without evidence of
LV hypertrophy by imaging methods may participate in athletic activities.
10, 15
Genotype positive phenotype negative HCM patients should supervise closely to monitor
the progression to hypertrophic phenotype.
10, 15
Non-compaction cardiomyopathy
Athletes who have a diagnosis of LVNC with normal EF, without symptoms and ventricular
tachycardias on ambulatory monitoring and stress testing may not be restricted from
athletic activities but close supervision needed.
15, 19, 20
Athletes with LVNC who have symptoms (especially syncope), reduced EF, thromboembolic
events, and ventricular tachycardias on ambulatory monitoring or stress testing should
be restricted from the athletic activities.
15, 19, 20
Asymptomatic athletes with hypertrabeculation and without a diagnosis of LVNC can
participate in all competitive sports.
15, 19, 20
Dilated Cardiomyopathy
Asymptomatic athletes with DCM and mildly decreased LV systolic function (EF> 40%),
may selectively participate in athletic activities.
15, 22
In DCM, athletes with symptoms or reduced LV ejection fraction (<40%) or frequent
and complex ventricular tachyarrhythmia in ambulatory ECG monitoring or exercise tests
or history of unexplained syncope should not be recommended to deal with athletic
acitivities.
15, 22
Myocarditis
If LV function and serum biomarkers of myocardial injury are normalized and no clinically
releveant aryythmia detected on 24 h ECG monitoring, it is reasonable for athletes
with myocarditis to return athletic activities under close supervision after a healing
period of 3 to 6 months.
10, 24
Athletes with myocarditis should be followed regularly in case of risk of recurrence
and silent progression of the disease especially during the first 2 years.
10, 24
Athletes with myocarditis should be restricted from athletic activities for a period
of 3 to 6 months.
10, 15, 24
Arrhythmogenic right ventricular cardiomyopathy
ARVC patients should not participate in high intensity athletic activities.
15, 27
Genotype positive phenotype negative ARVC patients should not participate in high
intensity athletic activities.
15, 27
ICD implantation in an athlete with ARVC for the sole purpose of participation in
high intensity athletic activity is not recommended.
15, 27
Commotio cordis
Commotio cordis survivors should undergo a complete cardiac study to exclude structural
heart disease and underlying arrythmic condition.
29, 30
After comprehensive evaluation of commotio cordis survivors, athletes without any
underlying cardiac disease can safely return to athletic activities.
29, 30
Coronary artery anomalies
Athletes with anomalous origin of a coronary artery without either symptoms or positive
stress test may be selectively participate in athletic acitivities after counseling
with the athletes and/or parents of the athlete.
15, 36, 43
After successful surgical repair; operated athletes with CAAs may consider to return
athletic activities 3 months after surgery if the athlete is asymptomatic and a stress
test shows no evidence of ischemia.
15, 36, 43
Athletes with anomalous origin of a coronary artery which shows an interarterial course
should be restricted from athletic acitivities before surgical repair.
15, 36, 43
Athletes with anomalous origin of a coronary artery who exhibits symptoms or arrythmias
or signs of myocardial ischemia in stress tests should be restricted from athletic
acitivities before surgical repair.
15, 36, 43
Channelopathies
Athletes with a suspected cardiac channelopathy should be evaluated by an experienced
heart rhytm specialist.
46, 47, 52
It is advised to perform sports in places with on-board automated-external-defibrillator
and near people who are already informed about the disease for athletes with channelopathy.
46, 47, 52
Asymptomatic athletes with genotype positive phenotype negative channelopathy might
be allowed to participate in all sports with appropriate precautionary measures.
46, 47, 52
It is recommended that symptomatic athletes with any suspected or diagnosed channelopathy
should be restricted from all competitive sports until a detailed evaluation has been
completed, appropriate treatment has been applied and asymptomatic status on therapy
has been provided for 3 months.
46, 47, 52
Drugs which induce a Brugada-pattern on ECGand drugs which prolongs QT interval should
be avoided in athletes with BrS and LQTS respectively.
46, 47, 52
Dehydration, excessive sweating, electrolyte disturbances, and hyperthermia should
be avoided for athletes with channelopathy.
46, 47, 52
Wolff Parkinson White syndrome
Athletes with high-risk characteristics during EP study should undergo RF ablation
to retain athletic eligibility.
52, 69
An athlete may return to athletic acvities after 3 months of successfull ablation
procedure in case of no recurrence of arrythmia.
52, 69
Athletes with implanted cardiac devices
Among athletes with ICD, performing an exercise test to determine the athlete’s upper
heart rate for tachycardia zone programming is recommended.
15, 73
Among the athletes with permanent pacemaker or ICD, only low–moderate intensity athletic
activities except those with risk of bodily collision are recommended.
15, 74
In asymptomatic athletes with Mobitz type 2 or complete AV block without structural
heart disease, a deconditioning period up to 2 months is recommended. Persisting or
recurring of symptoms after deconditioning may indicate pacemaker implantation.
15, 73
Asymptomatic athletes with sinus bradycardia or sinus pauses that are secondary to
elevated parasympathetic tone, permanent pacing should not be performed.
15, 74
Healthy athletes show a 10%–15% increase in both left and right ventricular cavity
size. In Olympic athletes, 45% have LV cavity size over the upper limits of normal.
Family history and additional ECG changes help establish the diagnosis of DCM. Diastolic
dysfunction and failure of improvement in LV systolic function on exercise echocardiography
suggests DCM. Additionally, low peak VO2 on cardiopulmonary testing, non-sustained
VT on Holter ECG, LGE on cardiac MRI, and positive genetic testing favor a diagnosis
of DCM (22).
Presence of symptoms, ejection fraction, and arrhythmic status are the main determinants
of an athlete with DCM who desires to participate in athletic activities.
Myocarditis
Myocarditis usually presents with symptoms of exertional dyspnea, chest pain, and
arrhythmia. It easily mimics acute coronary syndrome, and coronary angiography is
needed for the definite diagnosis (23). Autopsy studies in the series of sudden deaths
in athletes indicate that myocarditis is a significant cause. Among the US military
recruits, myocarditis-associated sudden death was found to be the most significant
etiology (24).
Acute myocarditis can lead to DCM and can be resolved after a period of time with
myocardial scar formation. This condition can lead to arrythmias both during the acute
and chronic phases. All physical activities should be restricted during acute myocarditis
and exercise recommendations should be tailored after acute phase according to the
clinical condition, laboratory, and imaging parameters of an athlete.
Arrhythmogenic right ventricular cardiomyopathy
ARVC is a hereditary myocardial disease caused by mutations, especially in genes encoding
desmosomic proteins. ARVC is histologically characterized by the loss of myocytes
in the right ventricular myocardium and/or LV myocardium with fibrofatty replacement
which results in segmental or diffuse wall thinning (25).
The ECG findings of ARVC include most commonly T wave inversion in precordial leads
V1 through V3 with a rare finding of Epsilon waves. The left bundle branch patterned
ventricular tachyarrhythmia can be observed in ARVC patients (25).
Echocardiography and cardiac MRI may show right ventricular dilation or segmental
wall motion abnormalities with morphological alterations. Fatty deposition in the
right ventricular wall can be identified with cardiac MRI.
Both ventricular cavities can dilate physiologically in response to chronic exercise
and this situation must be differentiated from the pathological conditions of ARVC.
Generally, no segmental wall motion defects are seen in the physiological state. A
positive family history along with ECG and echocardiographic findings may help identify
ARVC, and typical findings on cardiac MRI confirms the diagnosis (26).
The most important risk factors in athletes with ARVC include prior history of SCD,
sustained VT, or syncope (27).
Most of the SCDs in ARVC patients occur during exercise. Exercise itself can both
facilitate the natural progression of the disease and lead to lethal arrhytmias. Reducing
the intensity of the exercise in ARVC patients is associated with lower risk. Since
exercise and SCDs have a definite causative relationship in ARVC, competitive athletic
activities should be restricted in these patients.
Commotio cordis
Commotio cordis is defined as SCD due to ventricular fibrillation (VF) triggered by
a blunt, non-penetrating blow to the precordium. Although initially considered extremely
rare, it is now accepted as one of the most common causes of SCD in young athletes.
Commotio cordis predominantly affects young male athletes (28).
Blows occur on the left chest wall and usually involve impact from a hard spherical
object, such as a baseball, hockey ball, football, or volleyball. Strong body impacts
which can occur during sports like karate and boxing may also lead to commotio cordis.
Using soft balls or chest protection instruments during athletic activities can be
useful but not absolutely protective (29).
More recently, the Commotio Cordis registry suggested that survival rates have increased
steadily over the past 15 years, at >50%. Survival can be improved by earlier recognition
of commotio cordis, shortening of the time interval from collapse to cardiopulmonary
resuscitation, increased use of automated external defibrillators in the community,
and increased number of people receiving training in cardiopulmonary resuscitation
(30).
Coronary artery anomalies
The frequency of Coronary Artery Anomalies (CAAs) in the community is mostly learned
by autopsies, angiography, and other imaging techniques (31, 32). Even though different
results were also found in a number of angiography series, prevalence of CAAs have
been reported between 0.21% and 5.79% in older surviving subjects (33, 34). Autopsy
evaluation among military recruits and young athletes who experienced sudden death
shows that CAAs are responsible for 17%–44% of cardiovascular mortality (31, 35).
In order of frequency among the general population, CAAs with an abnormal origin might
present as the left circumflex artery originating from the right sinus valsalva, a
single coronary artery originating from the left sinus valsalva, all coronary arteries
originating from the right coronary sinus, or the left anterior descending coronary
artery (LAD) originating from the right coronary sinus (36). Among athletes who have
died suddenly, anomalous origin of LMCA and LAD from the right sinus valsalva is more
prevalent. The main clinical problem is the interarterial course of the left main
coronary artery, LAD, and right coronary artery. The course of the vessels between
the aorta and the pulmonary artery may cause compression of vessels, which in turn
could lead to myocardial ischemia, ischemic arrhythmias, and sudden death (37-39).
Anomalous origin of left coronary artery from the pulmonary artery (ALCAPA) is usually
an isolated anomaly. ALCAPA constitutes 0.22%–0.4% of congenital cardiac anomalies.
Most patients die within the first year after delivery, so it is rarely seen among
the athletes who have died suddenly (40).
The importance of preparticipation screening, especially in competitive young athletes,
is evident in order to reduce mortality and morbidity caused by CAAs. Unfortunately,
in contrast to congenital arrhythmia syndromes and cardiomyopathies, the diagnostic
power of ECG in asymptomatic CAAs is not very high.
Echocardiography is superior to detect the concomitant structural congenital heart
disease in athletes with CAAs. An experienced echocardiographer can inform us about
the origin of coronary ostia with 98% certainity. Transesophageal echocardiography
can be performed if the images are not clear enough (41, 42).
Since our aim is to protect a young person from the negative consequences of sport
activity, a maximal stress test must be performed in the third line after routine
ECG and echocardiography in athlete with a possible diagnosis of CAA. If the test
result is negative, it will carry him to a better level in terms of risk. If the stress
test is suspicious, myocardial perfusion scan or stress echocardiography will be the
best method to evaluate ischemia (43).
Recently, Multi Detector Computerized Tomography (MDCT) data became recognized as
an appropriate method to obtain the closest factual results. However, it is not practical
to use MDCT as a routine control test due to restrictions related to the usage of
X-ray and contrast agent (44, 45). Coronary angiography is indicated for definite
diagnosis, and intracoronary functional assesment may be required.
The only treatment method for CAAs in athletes is surgery. Absence of myocardial ischemia
must be demonstrated before returning to athletic activities in operated athletes.
Channelopathies
Long QT syndrome
Cardiac ion-channel disorders, also known as “Channelopathies”, are inherited primary
electrical disorders without “gross” cardiac structural abnormalities. Long QT syndrome
(LQTS) is the most frequent within this group of suggestively pure “electrical” diseases,
with an approximate prevalence of 1: 2000 (46, 47). The disease is characterized by
a prolongation of the QTc interval (heart rate corrected QT) due to the mutations
in genes encoding for subunits of potassium, sodium, or calcium voltage-dependent-ion-channels
in the absence of secondary causes (48, 49). It is associated with syncope or SCD
due to lethal ventricular arrhytmias (VAs), especially Torsades de Pointes, mainly
triggered by adrenergic activation. The conditions associated with arrhythmic events
are mostly gene-specific, with most arrhythmic events occurring during physical or
emotional stress in LQT1, at rest or in association with sudden noises in LQT2 patients,
and at rest or during sleeping in LQT3 patients (46, 47).
Restriction from virtually all competitive sports has formerly been the guideline-based
recommendation since 2005 for athletes with any cardiac channelopathy (50, 51). However,
starting from the “EHRA Expert Consensus Statement on the Inherited Primary Arrhythmia
Syndromes” by Priori et al. (47) and 2015 AHA statement paper (52), expert panels
tended to publish more liberal yet evidence-based recommendations (46, 47). ICD implantation
is recommended in patients with previous SCD and in patients with syncope and/or for
sustained VT occurring while receiving β blockers (46, 48).
In their milestone paper, Johnson et al. (53) sought for the outcomes of the global
conventional exercise restriction rules suggested in LQTS. 70 athletes (54%) were
competing contrary to European guidelines but within Bethesda guidelines (51, 54).
However, none had a sport-related event. Of the 60 LQTS athletes (46%) continuing
in sports contrary to both guidelines, only 1 experienced sporting-related events
being equal to “1” event in “331 athlete-years”. In a large Italian registry young
athletes with LQTS (0.6% of all non-eligible) were disqualified according to the contemporary
guideline. During follow-up, no cardiac events in the disqualified athletes were reported.
After more than 30 years of screening, the authors observed that only two of the LQTS
cases had died suddenly (55). These results revealed that incidence of serious cardiac
events in athletes with LQTS is lower than expected.
Athletes with LQTS should be supervised closely, and precautionary measures including
treatment options should be implemented effectively.
Short QT syndrome
Short QT syndrome (SQTS) is a rare channelopathy characterized by a reduced duration
of cardiac repolarization building the substrate for the development of lethal arrhythmias
(46, 48). Five genes have been linked to SQTS (KCNH2, KCNQ1, KCNJ2, CACNA1C and CACNB2b),
but the yield of genetic screening remains low (about 20% overall) (56). Resuscitated-SCD
might be the first manifestation of the disease with a peak incidence in the first
year of life (49, 56). SCD-survivors have a high recurrence rate; therefore, implantation
of ICD is strongly recommended in this group of patients with/without quinidine or
sotalol (46, 48). SQTS is diagnosed in the presence of a QTc ≤340 ms or QTc ≤360 ms
and one or more of the clinical disease features (46). Limited data are available
to quantify arrhythmic risk during competitive physical activity as-well-as genotype-phenotype
relations in SQTS patients while even “syncope” seems to fail in predicting future
events (46, 47). Individuals with SQTS should avoid dehydration, protein-supplements,
excessive sweating, and hyperthermia during exercise.
Brugada syndrome
Brugada syndrome (BrS) is characterized by SCD and/or syncopal events due to VT/VF
in young and apparently healthy individuals without significant medical history and
with classical ST-segment-elevation-patterns in right precordial ECG leads (46, 47).
BrS is inherited as an autosomal-dominant trait, which is more frequent in young adults
and in men (57). The prevalence ranges from 1/1000 to 1/10 000 (46, 58). Either a
decrease in the inward-sodium or calcium current or an increase in the outward-potassium-currents
has been shown to be associated with the BrS phenotype. Ventricular-arrhythmia/SCD
occurs at a mean 41±15 years, but it usually gets manifest during rest or sleep. ICD
implantation is the definitive therapy in BrS patients with aborted SCD or with a
history of cardiac-syncope and spontaneous type-1-pattern. The Brugada-pattern should
carefully be distinguished from Brugada-phenocopies, which is challenging in an athlete’s
ECG (59).
Data about the probable relation of exercise physiology and BrS is limited and mostly
mechanistic rather than prognostic (60, 61).
In a meta-analysis (62) which included anecdotal cases; ST augmentation was observed
during the early-recovery-phase of exercise in 57% of patients. There are insufficient
data on the risks of exercise in BrS to make a recommendation. According to observations
which suggest exercise might worsen the ST abnormalities in BrS and produce VA, patients
with BrS might be restricted from vigorous exercise (60, 61). There is a risk of activation
of temperature-dependent mutations at the climax of the exercise and sympathetic withdrawal
in BrS patients. However, SCD in BrS occurs most often during sleep (60, 61). Alltogether,
this limited evidence might imply an already high-risk subgroup of BrS individuals
manifesting their own poor-prognostic features instead of the detrimental effects
of the “exercise physiology” itself.
Randomized and prospective data is certainly needed in order to reveal mechanistic
relations and provide firm recommendations on cessation of sport participation. Until
then, we lack crude evidence to expel all BrS population from exercising, apart from
the high-risk-subgroup.
Catecholaminergic polymorphic VT
Catecholaminergic polymorphic VT (CPVT) is a rare, potentially life-threatening inherited
arrhythmia with an estimated prevalence of 1:10.000 (63). It is diagnosed in the presence
of a structurally normal heart, normal ECG, and unexplained exercise- or catecholamine-induced
bidirectional VT or polymorphic ventricular premature beats or VT in an individual
<40 years and/or in carriers of a pathogenic mutation in a CPVT-associated gene (47).
Patients with CPVT often present with symptoms during the first decade of their life
(63). Abnormal storage and release of calcium from the sarcoplasmic reticulum are
the suggested mechanisms (64).
Intense physical activity has been implicated as a trigger for life-threatening cardiac
arrhythmias in patients with CPVT. Exercise at a very low level should be allowed
after the approval of CPVT experts (46). Appropriate precautionary measures should
be taken during the physical activity of an athlete with CPVT including initation
of beta blocker therapy, electrolyte/liquid replacement, avoidance of dehydration,
acquisition of a personal automatic external defibrillator, and establishment of an
emergency action plan with the appropriate school or team officials (52).
Early repolarization syndrome
Early repolarization (ER) is a common ECG finding characterized by J-point elevation
≥1 mm ≥2 contiguous leads (47). The ER pattern in the precordial leads has been considered
a benign phenomenon, but its presence in the inferior and/or lateral leads has been
associated with idiopathic VF and/or polymorphic VT (ER syndrome) (47, 65). Non-anterior
ER pattern including the inferior subtype is commonly seen in young competitive athletes
(ranging from 14% to 44%) (66, 67). Noseworthy et al. (66) showed that both ER and
the inferior subtype increased in prevalence with intense physical training. These
data suggest that the ER pattern is a direct result of exercise training. ST-segment
morphology variants associated with ER may help separate subjects with and without
an increased risk of arrhythmic death in middle-aged subjects. Rapidly ascending ST
segments after the J-point, which is the dominant ST pattern in healthy athletes,
are not associated with an increased risk for arrhythmic death (68).
In conclusion, there is no evidence of an increased risk of SCD in healthy athletes
with an ER pattern (63, 67, 68). Competitive sports may be allowed for a previously
symptomatic athlete with ER syndrome with appropriate precautionary measures (52).
Wolff Parkinson White syndrome
The prevalence of Wolff Parkinson White (WPW) pattern is estimated to be 1–3 in 1000
individuals (69). Approximately 65% of adolescents and 40% of individuals over 30
years with a WPW pattern are estimated to be asymptomatic. Ventricular pre-excitation
accounts for approximately 1% of SCD in athletes (4). SCD may occur due to the development
of atrial fibrillation (AF) with a rapid ventricular response that degenerates to
VF (70). The main risk factor for SCD is the presence of an accessory pathway (AP)
with short antegrade refractoriness (7).
Radiofrequency (RF) ablation should be performed in patients with WPW syndrome resuscitated
from aborted cardiac arrest due to AF and rapid conduction over the AP causing VF
(46, 69). If an athlete is symptomatic with syncope or palpitation, an electrophysiologic
(EP) study is recommended. RF ablation is recommended if the refractory period of
the AP pathway is ≤240 ms or the shortest preexcited RR interval is <220 ms during
induced AF (46, 69). After 3 months of successfull ablation procedure, an asymptomatic
athlete may return to athletic activities.
Approximately 65% of adolescents and 40% of individuals over 30 years with a WPW pattern
are estimated to be asymptomatic (69). According to the 36th Bethesda Conference,
an EP study is recommended for asymptomatic athletes if they participate in moderate-
or high-level competitive sports (54). The ESC mandates that all athletes with WPW
undergo an EP study for risk assesment (52). Asymptomatic patients with a short preexcited
RR interval ≤250 ms in AF or <220 ms during stress or isoproterenol, the refractory
period of the AP ≤240 ms, presence of multiple APs, or easily induced AF are at increased
risk for SCD (47, 69). Athletes with high-risk characteristics mentioned above during
EP study should undergo RF ablation to retain athletic eligibility. In addition, asymptomatic
patients with WPW and structural heart disease or ventricular dysfunction secondary
to dyssynchoronous contractions may be considered for ablation regardless of the antegrade
characteristics of the AP (69).
Athletes with implanted cardiac devices
Athletes with permanent cardiac pacemakers
Highly-trained endurance athletes have dominant parasympathetic tone at rest associated
with marked sinus bradycardia, first degree and Mobitz type I atrioventricular block.
Mostly these findings are physiological events that do not require intervention (71).
Underlying structural heart disease should be excluded in case of Mobitz type 2 atrioventricular
block or third-degree atrioventricular block (72).
Potential risk for device and lead damage may limit the professional life of athletes.
The 36th Bethesda Recommendations state that PM dependent athletes should not participate
in sports that can involve bodily trauma (1). Although not addressed in formal recommendations,
protection with padding might be considered. Programing upper tracking rates at higher
levels is important in athletes with complete heart block. Heart rates of the patient
during vigorous exercise should be considered. Myopotential inhibition may lead to
inhibition of pacing, which is of concern in pacemaker-dependent patients. Therefore,
bipolar leads should be selected in athletes.
Athletes with ICD
It should be kept in mind that ICDs do not prevent the occurrence of ventricular arrhythmias
and do not effect the progression of the underlying disease. Therefore, careful consideration
of the underlying disease is mandatory before participation in competitive sports
(15).
However, a long-term prospective multinational registry provides promising data about
this topic. After a mean follow-up period of 44 months of 440 patients, there were
no arrhythmic deaths, externally resuscitated tachyarrhythmias during sports participation,
or injury resulting from arrhythmia-related syncope or shock during sports (73). 31
definite and 13 possible lead malfunctions were reported. The estimated lead survival
free of definite plus possible malfunction was 94% at 5 years and 85% at 10 years.
No generator malfunction was reported.
On the other hand, approximately one in five received both appropriate and inappropriate
shocks, which mainly occurred during competition or physical activity. Therefore,
programing an ICD of an athlete is always challenging due to the risk of inappropriate
shocks from high heart rates during exercise. Recently, the role of ICD programming
characteristics on occurrence of shocks, transient loss of consciousness, and death
among athletes was assessed by prospective, observational, international registry
(74). High-rate cutoff and long-detection duration programming in athletes was associated
with reduction in total and inappropriate ICD shocks without affecting survival or
the incidence of transient loss of consciousness. Since it is not easy to recommend
certain tachycardia detection zones, patient-tailored programming seems a better approach.
The potential risks associated with mechanical trauma are possible for ICDs. The athlete’s
ability to participate in sports should be discussed individually. Underlying cardiovascular
disease, type and the programing of the device, type of the sport, risk for trauma,
and risks related to potential syncope or shock should be considered.
Conclusion
Specific return-to-play protocols should be developed for competitive athletes following
treatment of various cardiovascular conditions like cathater ablation, cardiac device
implantation, and corrective surgeries.
Athletic activities performed in a competitive fashion could have hazardous effects
on the cardiovascular health of the athletes. Athletes who have high-risk genetic
cardiovascular diseases and implanted cardiac devices should be closely supervised
by sports cardiologists, exercise specialists, and their personal trainers in a deep
collaboration with the guidance of professional and scientific recommendations.