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Sudden Cardiac Death in<br />
Athletes<br />
Farzin Halabchi, M.D.<br />
Fhalabchi@tums.ac.ir
Definition<br />
Nontraumatic, nonviolent, unexpected<br />
death due to cardiac causes within 1<br />
hour of the onset of symptoms<br />
(witnessed event), or within 6 hours of<br />
witnessed normal state of health<br />
(unwitnessed event). Sports-related<br />
deaths are defined as those with<br />
symptoms occurring during or within 1<br />
hour after sports participation.
Other definitions limit the time frame<br />
in relation to sport participation <strong>and</strong><br />
symptoms anywhere from within 1 to<br />
24 hours.
Rosen<br />
Sudden unexpected death, defined as<br />
death within 24 hours of symptom onset<br />
in a previously functional individual,<br />
accounts for one third of all nontraumatic<br />
deaths, with most occurring<br />
outside the hospital. Of these, 75% are<br />
attributed to cardiovascular disease,<br />
with the remaining 25% attributed to<br />
noncardiac causes.
History<br />
The first recorded sudden death of<br />
an athlete: Pheidippides (490 bc).<br />
The more recent deaths of several<br />
well-known athletes have brought<br />
SCD into the public consciousness.
marathon runner Jim Fixx (1984)<br />
Olympic volleyball player Flo Hyman (1986)<br />
former basketball star Pete Maravich (1988)
professional basketball All-Star<br />
Reggie Lewis (1993)<br />
Olympic figure skating champion<br />
Sergei Grinkov (1995)<br />
Cameron national soccer player<br />
Mark Vivien Foe (2003)
Epidemiology<br />
The exact incidence of SCD is difficult to ascertain,<br />
because many studies have relied on the self-reporting<br />
of physicians <strong>and</strong> media accounts of deaths.<br />
The National Federation of State High School<br />
Associations: 10-25 SCD per year in individuals<br />
younger than 30 years.<br />
Data compiled from 1965 to 1985: 1 per 735000<br />
screened US Air Force recruits between 17 <strong>and</strong> 28<br />
years of age.<br />
A study of Minnesota high schools: 3 SCD during a 12year<br />
period, translating to a risk of 1 death per 200000<br />
athletes per year.<br />
Rhode Isl<strong>and</strong>: SCD during exercise in unscreened men<br />
younger than 30 years was estimated to be 1 death per<br />
280000 men per year.
L<strong>and</strong>mark studies<br />
Maron et al: 134 SCD among young,<br />
competitive athletes (1985-1995)<br />
The mean age was 17 years (range,<br />
12 to 40 years); 90% were male <strong>and</strong><br />
44% were black.<br />
Basketball <strong>and</strong> football players<br />
accounted for 68% of the deaths.
L<strong>and</strong>mark studies<br />
The National Center for Catastrophic<br />
Sports Injury Research: 160 SCD (78%<br />
from cardiac causes) in high school <strong>and</strong><br />
college sports (1983-1993).<br />
The estimated death rate of male athletes<br />
was 5-fold higher than for female athletes<br />
(7.47 versus 1.33 per 1000000 athletes per<br />
year)<br />
basketball or football (65%)<br />
Interestingly, male college athletes had<br />
twice the estimated death rate of their high<br />
school counterparts (14.5 versus 6.6 per<br />
1000000 athletes per year).
France<br />
Institute of Forensic Medicine of Paris: 31<br />
SCDs during sports activities (1991-2001)<br />
29 male subjects, ranging in age from 7 to 57<br />
years (mean 30 years) <strong>and</strong> two female<br />
subjects, 8 <strong>and</strong> 60 years old, died suddenly<br />
during sports activities.<br />
The sports involved were various, with<br />
running the most frequent: 13 cases.<br />
Cardiomyopathies (10 cases) <strong>and</strong> coronary<br />
artery disease (9 cases): the most frequent<br />
causes<br />
Despite the severity of lesions, only 4 subjects<br />
had a known cardiovascular disease.
Croatia<br />
6 SCDs in male athletes during or after<br />
training (1973-2002)<br />
2 soccer players, 2 athletic runners, one rugby<br />
player <strong>and</strong> one basketball player<br />
All were without cardiovascular symptoms.<br />
Autopsy: hypertrophic cardiomyopathy (2),<br />
myocarditis, acute MI of the posterior wall,<br />
hypoplastic right coronary artery <strong>and</strong> ARVD<br />
All the 6 athletes died suddenly, obviously<br />
because of malignant ventricular arrhythmias.
Etiology (Brukner)<br />
Common:<br />
Hypertrophic cardiomyopathy<br />
Congenital coronary anomalies<br />
Aortic rupture (e.g. Marfan syndrome)<br />
Less common:<br />
Myocarditis<br />
MVP<br />
Aortic stenosis<br />
Arrhythmogenic right ventricular dysplasia (ARVD)<br />
Conduction abnormalities, including Wolff-Parkinson-White<br />
syndrome<br />
Prolonged QT syndrome<br />
Dilated cardiomyopathy<br />
Coronary artery disease
Etiology (AJEM)<br />
HCM (most common): at least 36%<br />
Congenital coronary anomalies: 17% to 19%<br />
Idiopathic left ventricular hypertrophy (ILVH):9% to<br />
10%<br />
Infrequent causes<br />
Aortic rupture<br />
Arrhythmogenic right ventricular dysplasia (ARVD)<br />
Aortic valve stenosis<br />
Prolonged QT syndrome<br />
MVP<br />
Commotio cordis<br />
WPW
Etiology USA<br />
Hypertrophic cardiomyopathy (36%)<br />
Coronary artery abnormalities (19%)<br />
Increased cardiac mass (10%)<br />
The remaining: myocarditis, Marfan, MVP,<br />
dysrhythmias, AS, WPW, idiopathic long<br />
QT syndrome, ARVD, cocaine <strong>and</strong><br />
anabolic steroid use, bulimia, anorexia<br />
nervosa, bronchospasm <strong>and</strong> heat-related<br />
illness. Coronary artery disease in<br />
adolescent athletes, unlike in the adult<br />
population, is an uncommon cause of<br />
sudden death.
Italy (Veneto region)<br />
200 SCDs (1978-1993) in the young (
Italy<br />
To establish the impact of sport activity on<br />
the risk of sudden death: From 1979 to<br />
1999, there were 300 SCDs in adolescents<br />
<strong>and</strong> young adults (12 to 35 years old),<br />
producing an overall cohort incidence rate<br />
of one per 100 000 persons per year.<br />
55 SCDs among athletes (2.3 per 100 000<br />
per year) <strong>and</strong> 245 among non-athletes (0.9<br />
per 100 000 per year), with an estimated<br />
relative risk (RR) of sudden death from all<br />
causes of 2.5.
Italy<br />
The rates of sudden death by<br />
cardiovascular diseases were 2.1 in<br />
100000 athletes per year, compared with<br />
0.7 in 100 000 non-athletes per year<br />
The cardiovascular causes at highest<br />
risk of sport-related SCD were<br />
anomalous origin of coronary artery,<br />
ARVC <strong>and</strong> premature coronary artery<br />
disease.
France<br />
31 SCDs: 29 male subjects, ranging<br />
in age from 7 to 57 years (mean 30<br />
years) <strong>and</strong> two female subjects, 8<br />
<strong>and</strong> 60 years old, died suddenly<br />
during sports activities. 13 cases.<br />
Cardiomyopathies (10 cases) <strong>and</strong><br />
coronary artery disease (9 cases)<br />
were the most frequent causes of<br />
deaths.
Iran<br />
In a retrospective study all of the cases of<br />
SCD, which were autopsied at the Tehran<br />
Legal Medicine Center in young individuals<br />
(15-31 years old), were reviewed.<br />
This survey covers approximately a 2.5 years<br />
period (1997-2000).<br />
73 cases (59males <strong>and</strong> 14 females) were<br />
expired due to SCD. Eight of them (11%) had<br />
died either during or after sports (6 cases in<br />
soccer <strong>and</strong> 2 in body building), all of them<br />
were male.
Among non sports-related SCDs in<br />
the male group, MI <strong>and</strong> severe<br />
atherosclerosis accounted for 51%<br />
overall, cardiomyopathies for 13.7%<br />
<strong>and</strong> other causes for 35.3%. In<br />
sports-related SCD group,<br />
cardiomyopathies were the common<br />
cause (3 cases). MI (1 Case), AS (1<br />
case) <strong>and</strong> primary arrhythmia (3<br />
cases).
Hypertrophic cardiomyopathy<br />
The estimated prevalence of HCM in the general<br />
population is about 1 in 500, although many cases<br />
may go undetected during a patient’s lifetime.<br />
The diagnostic criteria for HCM include a left ventricle<br />
that is hypertrophied but not dilated in the absence of<br />
other cardiac or systemic diseases that would<br />
produce left ventricular hypertrophy. This pathological<br />
hypertrophy contributes to decreased ventricular<br />
compliance <strong>and</strong> diastolic dysfunction with impaired<br />
filling. The left ventricular outflow obstruction <strong>and</strong><br />
possibly small lumen intramural vessels may<br />
potentiate myocardial ischemia. Arrhythmias arise in<br />
the context of an electrically unstable myocardial<br />
substrate caused by cardiac muscle cell<br />
disorganization, replacement fibrosis, or myocardial<br />
ischemia.
Hypertrophic cardiomyopathy is<br />
genetically transmitted as an AD condition<br />
with variable expression because it may<br />
not manifest itself until adolescence or<br />
young adulthood. If a family history of<br />
HCM is confirmed, it is recommended that<br />
all first-degree relatives be examined with<br />
echocardiography. It may be difficult,<br />
however, to distinguish mild HCM from the<br />
normal cardiac hypertrophy that occurs in<br />
highly trained athletes.
There are two types of HCM, the<br />
obstructive type <strong>and</strong> the much more<br />
common non-obstructive type. The<br />
anatomical feature of this condition<br />
include an increased heart weight<br />
(>360 g) <strong>and</strong> asymmetrical ventricular<br />
wall thickening.
Unfortunately, often the first clinical<br />
manifestation of HCM is sudden death. In a<br />
series of SCD occurring during exercise<br />
inpatients with HCM, only 35.7% had a<br />
previous cardiac evaluation for risk factors<br />
that included syncope, family history,<br />
murmurs, fatigue, or ventricular tachycardia<br />
on exercise testing. In another study, 21%<br />
of athletes who died from HCM had<br />
symptoms of cardiovascular disease before<br />
their death.<br />
In those who had prodromal symptoms, the<br />
most prominent were exertional dyspnea<br />
(the most common symptom), chest pain,<br />
palpitation as well as presyncope <strong>and</strong><br />
syncope.
HCM should be suspected in any patient<br />
with a typical systolic ejection murmur<br />
These patients will also demonstrate<br />
signs of left ventricular enlargement<br />
electrocardiographically <strong>and</strong><br />
radiographically.<br />
If HCM is suspected clinically, the<br />
diagnosis should be confirmed by<br />
echocardiography.<br />
If seen in the ED, patients should be<br />
proscribed from exertion or exercise<br />
until they can have an echocardiogram<br />
<strong>and</strong> cardiology consultation.
Physical Findings<br />
Rapid, jerky upstroke of the carotid pulse<br />
A double or triple apex beat<br />
harsh systolic ejection murmur at the lower<br />
LSB medial to the apex (increases in intensity<br />
with maneuvers that decrease venous return<br />
such as Valsalva’s maneuver or st<strong>and</strong>ing <strong>and</strong><br />
decreases with squatting, leg raise <strong>and</strong><br />
clenching fist).<br />
wide splitting of S2<br />
third heart sound is common, owing to<br />
greater diastolic filling rates<br />
fourth heart sound may be heard as a result<br />
of vigorous atrial contractions in individuals<br />
with thin chest walls.
Echocardiographic Findings<br />
(investigation of choice)<br />
marked, asymmetrical LV wall thickening<br />
(septum disproportionately greater than<br />
the LV free wall, with an average thickness<br />
of ≥20mm)<br />
diminished LV cavity size (
Note:<br />
Elite athletes with left<br />
ventricular hypertrophy<br />
may show a reduction<br />
in wall thickness of<br />
about 2-5 mm with 3<br />
months of<br />
deconditioning. A<br />
decrease such as this<br />
would be inconsistent<br />
with HCM.
Echocardiographic Findings<br />
While the anterior ventricular septum<br />
is usually the predominant region of<br />
hypertrophy, virtually all patterns of<br />
left ventricular occur in HCM. For<br />
example, although many patients<br />
show diffusely distributed<br />
hypertrophy, about 30% demonstrate<br />
localized wall thickening confined to<br />
only one left ventricle segment.
Electrocardiographic Findings<br />
dramatically increased QRS voltage suggesting<br />
LV hypertrophy with ST-T wave pattern of LV<br />
strain is most common<br />
some patients have deep septal Q waves<br />
deeply (>0.2 mV) inverted T waves in precordial<br />
leads<br />
ST segment flattening, depression or both<br />
Left axis deviation<br />
ventricular tachycardia or paroxysmal atrial<br />
fibrillation.<br />
A normal ECG makes the diagnosis unlikely.
Hypertrophic cardiomyopathy. Note the prominent RS wave<br />
in leads V1 <strong>and</strong> V2 as well as the lateral Q waves. This ECG<br />
was performed in a patient with syncope occurring during a<br />
sprint at football practice. Echocardiography confirmed<br />
HCM.
Apical hypertrophic cardiomyopathy. Normal sinus<br />
rhythm with LVH <strong>and</strong> deeply inverted T waves in the<br />
mid <strong>and</strong> lateral precordial leads. T wave abnormality<br />
is also present in the inferior leads in this patient.
Histological Findings<br />
histological disarray of myocyte<br />
architecture<br />
increased number of abnormal<br />
intramural coronary arteries with<br />
thickened walls<br />
narrowed lumens
Recommendations for<br />
diagnostic evaluation<br />
C<strong>and</strong>idates with relatives who have been<br />
diagnosed with HCM should undergo a<br />
cardiovascular examination that includes<br />
at least a 12-lead ECG <strong>and</strong> 2Dechocardiography.<br />
When these tests suggest the diagnosis<br />
of HCM, a comprehensive cardiac<br />
evaluation (including exercise stress test,<br />
24-hour ECG Holter monitoring) is<br />
recommended.
Recommendations for<br />
participation in athletic activities<br />
C<strong>and</strong>idates with unequivocal diagnosis of<br />
HCM who are < 35 years of age should avoid<br />
strenuous training <strong>and</strong> athletic competition.<br />
They should not participate in any<br />
competitive athletic activities (regardless of<br />
medical treatment, absence of symptoms, or<br />
implantation of defibrillator) with the<br />
possible exception of the low-intensity<br />
physical activities (Class IA).
Recommendations for<br />
participation in athletic activities<br />
C<strong>and</strong>idates with unequivocal diagnosis of HCM who are<br />
>35 year of age <strong>and</strong> have no risk factors (e.g., family<br />
history of sudden death, syncope, sustained or nonsustained<br />
ventricular tachycardia, marked left ventricular<br />
hypertrophy, left ventricular outflow gradient >50 mmHg,<br />
exercise-induced ischemia or hypotension, <strong>and</strong> carriers<br />
of certain high-risk genes) may reasonably be considered<br />
at low risk for sudden cardiac death. In selected subjects,<br />
participation in mild to moderate athletic activities<br />
(Classes IA, IB, <strong>and</strong> IIA) may be allowed, as long as<br />
periodic evaluations are done at least once a year.
Treatment strategies (improve or<br />
relieve the symptoms)<br />
Traditionally, b-blockers have been the initial treatment of<br />
exertional dyspnea or chest pain (decrease in heart rate,<br />
improvement of ventricular filling during diastole, decrease in<br />
myocardial oxygen dem<strong>and</strong>, <strong>and</strong> reduction of sympathetic tone).<br />
Alternatively, verapamil has been used effectively in patients<br />
who either cannot tolerate a b-blocker (eg, severe asthmatic) or<br />
have no initial response to beta-blockade.<br />
Disopyramide, a class IA antiarrhythmic drug, used most often<br />
in conjunction with a b-blocker, has been used as an alternative<br />
to verapamil <strong>and</strong> may relieve symptoms through its negative<br />
inotropic properties.<br />
If a patient develops signs of left ventricular systolic<br />
dysfunction (ie, congestive heart failure), afterload-reducing<br />
agents, b-blockers, digoxin, <strong>and</strong> judicious use of diuretics are<br />
indicated.<br />
It is important to note that the administration of a b-blocker or<br />
verapamil to patients with HCM does not protect them from<br />
sudden death.
Nonpharmacologic therapies are reserved<br />
for the minority of patients with HCM who<br />
fail medical management.<br />
Surgical septal myomectomy<br />
Alcohol septal ablation is a newer<br />
procedure. This procedure produces a<br />
modest infarction of the myocardial<br />
septum that results in subsequent<br />
akinesis, septal thinning, <strong>and</strong> fibrosis
Recommendations for participation in<br />
athletic activities<br />
C<strong>and</strong>idates with HCM diagnosed among<br />
relatives, but who do not have evidence of HCM<br />
based on a 12-lead ECG <strong>and</strong> 2Dechocardiography,<br />
should be restricted from<br />
competitive athletic activities during<br />
adolescence until full body growth is reached.<br />
After that, c<strong>and</strong>idates who do not show<br />
evidence of HCM may participate in sport<br />
activities without restrictions, with the<br />
recommendation of periodic follow-up <strong>and</strong><br />
testing.
Coronary Artery Anomalies<br />
The second most common cause of<br />
exercise-induced SCD in young athletes<br />
Presumably lead to myocardial<br />
hypoperfusion during exercise<br />
They are rarely diagnosed during life<br />
The most common coronary anomaly<br />
associated with SCD is an anomalous<br />
origin of the left main coronary artery<br />
from the right anterior sinus of Valsalva.
Possible reasons for ischemia in<br />
anomalous coronary artery include a slit-<br />
like ostium that narrows with aortic<br />
dilatation during exercises, an acute-<br />
angled takeoff, <strong>and</strong> compression of the<br />
artery as it passes between the aorta <strong>and</strong><br />
pulmonary trunk.
Anatomy – Coronary Arteries
Some individuals may demonstrate<br />
symptoms such as syncope or<br />
angina before an event.<br />
Among athletes who died of this<br />
disorder, 31% were found to have<br />
symptoms before death.<br />
A high index of suspicion in<br />
conjunction with an echocardiogram<br />
may help suggest the presence of an<br />
anomaly in order for angiography to<br />
be obtained <strong>and</strong> to confirm this often<br />
surgically correctable abnormality.
Both MRI <strong>and</strong> CT coronary<br />
angiography have demonstrated<br />
promise in detecting coronary artery<br />
anomalies.<br />
Single coronary arteries, coronary<br />
artery hypoplasia <strong>and</strong> pulmonary<br />
artery serving as the origin for the<br />
coronary arteries have also been<br />
associated with SCD.
Idiopathic left ventricular<br />
hypertrophy<br />
Is a symmetric, concentric hypertrophy where<br />
the left ventricular mass exceeds that of<br />
physiological hypertrophy. Unlike HCM, is not<br />
associated with genetic transmission <strong>and</strong> there<br />
is no cellular disarray microscopically.<br />
It is uncertain whether some cases of ILVH<br />
represent mild morphological expressions of<br />
HCM, unusual instances of exercise-induced<br />
cardiac hypertrophy (athlete’s heart syndrome)<br />
with nonbenign consequences, or possibly<br />
examples of undetected right ventricular<br />
dysplasia with mild left ventricular hypertrophy.
Myocarditis<br />
Is frequently the result of a viral infection most<br />
commonly caused by either coxsackie virus (B) or<br />
echovirus.<br />
Characteristic symptoms of myocarditis include a<br />
prodromal viral illness followed by progressive exercise<br />
intolerance <strong>and</strong> congestive symptoms of dyspnea,<br />
cough, <strong>and</strong> orthopnea.<br />
When evaluating an athlete with an acute illness, a<br />
tachycardia out of proportion to other systemic features<br />
should alert the clinician to the possibility of<br />
myocarditis.<br />
On physical examination, an audible S3 gallop or soft<br />
apical murmur as well as signs of congestive heart<br />
failure may be present.<br />
ECG may show low-voltage complexes, diffuse STsegment<br />
<strong>and</strong> T-wave changes, <strong>and</strong> sinus tachycardia.
It can also cause arrhythmias ranging<br />
from PVC <strong>and</strong> premature atrial<br />
contraction (most common) to atrial<br />
fibrillation or life-threatening ventricular<br />
arrhythmias (uncommon).<br />
The severity of arrhythmia does not<br />
seem to correlate with severity of<br />
myocardial dysfunction.<br />
The stage of the myocarditis <strong>and</strong> the<br />
timing of sudden arrhythmic death<br />
cannot always be correlated.
Endomyocardial biopsy <strong>and</strong> histological<br />
examination of immunochemically stained<br />
myocardium may clarify the diagnosis,<br />
although patchy involvement may yield low<br />
sensitivity.<br />
Sudden cardiac death may occur in the<br />
presence of either active or healed<br />
myocarditis. Thus, a convalescent period of<br />
at least 6 months is recommended before a<br />
return to sports. After this period, if clinical<br />
features, ECG - Echocardiogram (at rest <strong>and</strong><br />
during exercise) <strong>and</strong> Holter monitoring are all<br />
normal, the athlete may return to<br />
competition.
Reevaluation may include a Holter<br />
monitor to establish the absence of<br />
arrhythmias, echocardiography to<br />
assess normal cardiac dimensions<br />
<strong>and</strong> function, <strong>and</strong>/or exercise stress<br />
testing with or without stress<br />
echocardiography.
Arrhythmogenic right<br />
ventricular dysplasia (ARVD)<br />
The most common cause of sudden death<br />
in young athletes in the Veneto region of<br />
Northern Italy.<br />
Is an AD condition leading to fibrosis <strong>and</strong><br />
fatty infiltration of the right ventricle,<br />
resulting in the thinning <strong>and</strong> dilatation of<br />
the right ventricular wall <strong>and</strong> leads to<br />
recurrent <strong>and</strong> intractable ventricular<br />
tachyarrhythmias.
In 25 to 30% of cases, ARVD is<br />
familial.<br />
About half of the subjects with ARVC<br />
may be symptomatic (with syncope<br />
<strong>and</strong>/or palpitations) before the<br />
occurrence of sudden death.
The first clinical sign of ARVD is<br />
often the occurrence of right<br />
ventricular tachycardia, frequently<br />
triggered by exercise (most common:<br />
isolated premature ventricular beats<br />
to sustained ventricular tachycardia).
Diagnosis<br />
Physical findings: although the most<br />
frequent physical finding in ARVD is<br />
a widely split S2 caused by<br />
prolonged right ventricular ejection,<br />
physical findings in 50% of this<br />
population are essentially<br />
unremarkable.
ECG changes in the majority of cases show a<br />
negative T wave from precordial leads V1-V3 (in<br />
subjects < 15 years). QS complexes in V 1-3 <strong>and</strong><br />
epsilon waves. An even larger number of<br />
individuals demonstrate re-entrant<br />
dysrhythmias manifested by polymorphic PVCs<br />
[left bundle-branch block morphology]. vertical<br />
axis also support the presence of the disease.<br />
Chest roentgenogram may reveal right<br />
ventricular enlargement.<br />
Echocardiographic changes demonstrate a<br />
large, poorly contractile right ventricle with thin<br />
walls.
ARVC
Criteria for the differential diagnosis of<br />
ARVC from athlete’s heart
MRI represents the most sensitive<br />
noninvasive diagnostic testing to<br />
identify (or raise suspicion of) this<br />
disease.
Wolff-Parkinson-White syndrome<br />
An additional electrical pathway can lead to<br />
tachycardia (>300 beats/min) <strong>and</strong>, rarely, SCD.<br />
This conduction abnormality is relatively rare,<br />
affecting only 0.15% to 0.2% of the general<br />
population, <strong>and</strong> has a very small risk of<br />
sudden death (
This disease does not show AD or AR<br />
inheritance.<br />
Sudden death may be the first clinical<br />
presentation in these subjects <strong>and</strong> may<br />
occur also in adult or mature age.<br />
The mechanism of SCD is the<br />
development of atrial fibrillation with rapid<br />
atrioventricular conduction via the bypass<br />
tract, resulting in rapid ventricular<br />
response <strong>and</strong> subsequent ventricular<br />
fibrillation.
The resting ECG may demonstrate an initial<br />
slurred upstroke of the QRS complex (delta<br />
wave), short PR interval, <strong>and</strong> wide QRS<br />
complex.<br />
The vast majority of WPW patients are<br />
diagnosed by the resting 12-lead ECG pattern.<br />
However, the preexcitation pattern may be<br />
present only occasionally in the resting 12lead<br />
ECG, due to changes in the accessory<br />
pathway refractoriness.
WPW
WPW
Treatment of symptomatic patients is<br />
with radiofrequency ablation. If athletes<br />
are free of symptoms three to six<br />
months after radiofrequency ablation,<br />
then they can resume sport with no<br />
limitation.
Brugada syndrome<br />
A syndrome of SCD caused by unpredictable<br />
episodes of recurrent ventricular tachycardia<br />
Is characterized by a 12-lead ECG pattern of<br />
right bundle branch block <strong>and</strong> ST-segment<br />
elevation in right precordial leads V1 to V3. It<br />
is usually associated with rapid polymorphic<br />
ventricular arrhythmia leading to sudden<br />
death.<br />
It is characterized as a syndrome of SCD in<br />
individuals with a structurally normal heart<br />
<strong>and</strong> no evidence of atherosclerotic coronary<br />
artery disease.
Brugada syndrome<br />
Originally thought to be a disease<br />
primarily of men from Southeast Asia, it is<br />
now identified in women, children, <strong>and</strong><br />
non– Asian ethnic groups.<br />
Patients may present with self-terminating<br />
episodes of ventricular tachycardia during<br />
exertion. If the diagnosis is supported by<br />
ECG findings, referral should be made for<br />
EP testing <strong>and</strong> consideration of automated<br />
implantable cardiac defibrillator<br />
placement.
Brugada syndrome. Note the<br />
incomplete RBBB with downsloping<br />
concave ST-segment elevation in<br />
leads V1 through V3.
Long QT syndrome<br />
The long QT syndrome is an abnormality of the electrical<br />
conduction system characterized by prolonged<br />
repolarization of the ventricle with an associated high risk<br />
of SCD.<br />
This syndrome can be congenital, pharmacogenic, or<br />
metabolic.<br />
It is often defined as a corrected QT interval of more than<br />
440 milliseconds.<br />
The mechanism of SCD is the development of wide,<br />
polymorphic tachycardia (ie, torsades de pointes). These<br />
potential fatal rhythms can be provoked by exerciserelated<br />
tachycardia<br />
Anyone with this condition should be restricted from<br />
competitive sports.
Determination of the QT interval. One of 2<br />
methods can be used to determine the<br />
length of the QT interval.<br />
In normal sinus rhythm with rates between<br />
60 <strong>and</strong> 100 beats per minute, a normal QT<br />
interval is less than one half the<br />
accompanying RR<br />
interval. Alternatively, the Bazzet formula<br />
can be used to calculate the specific,<br />
corrected QT interval—the QTc interval.
Bazett: QTc = QT{HR/60} 1/2<br />
Fridericia: QTc = QT{HR/60} 1/3<br />
Framingham: QTc = QT + 0.154{1 –<br />
(60/HR)}<br />
Van de Water: QTc = QT –<br />
0.087{(60/HR) – 1}
Long QT Syndrome
Long QT syndrome.
V-tach that changes orientation<br />
(changes QRS axis) regularly over a<br />
period of many beats is called<br />
Torsades de pointes.
Congenital LQTS is predominantly a<br />
hereditary disorder, usually transmitted in<br />
an AD manner. In a smaller number of<br />
affected subjects, transmission is AR <strong>and</strong><br />
associated with sensorineural deafness.<br />
This disorder is associated with torsade de<br />
pointes, usually precipitated by emotional<br />
circumstances <strong>and</strong>/or physical activity, <strong>and</strong><br />
presents clinically with syncope <strong>and</strong> sudden<br />
death.
LQTS is a relatively rare cause of<br />
sudden death in young individuals,<br />
including athletes, <strong>and</strong> usually occurs<br />
in subjects with a history of recurrent<br />
syncope.<br />
Sudden death has been found in family<br />
members <strong>and</strong> carriers of LQTS who do<br />
not show long QT intervals on their<br />
resting 12-lead ECG.<br />
Exclusion from all competitive sports.
Mitral valve prolapse<br />
Idiopathic MVP is the most common valvular<br />
disorder, occurring in approximately 5% of the<br />
population.<br />
Although sudden death from MVP has been<br />
reported, it is extremely rare <strong>and</strong> most athletes<br />
with MVP are totally asymptomatic.<br />
Physical examination of patients with MVP may<br />
reveal a midsystolic click <strong>and</strong> a late systolic<br />
murmur.<br />
If an athlete with known MVP develops syncope,<br />
exertional chest pain, or moderate-to-severe<br />
mitral regurgitation, or has a family history of<br />
MVP <strong>and</strong> sudden death, exclusion from athletic<br />
participation is recommended.
Aortic rupture<br />
Aortic rupture makes up 5% to 7% of<br />
sudden death in young athletes. Half of<br />
these cases occur in athletes with the<br />
Marfan syndrome,<br />
In the Marfan syndrome, the aortic media<br />
are deficient in the number of elastic<br />
fibers, which leads to weakening of the<br />
aortic wall (cystic medial necrosis) <strong>and</strong><br />
predisposes the individual to aortic<br />
dissection <strong>and</strong> death.
Marfan Syndrome<br />
An AD disorder with a<br />
prevalence in the general<br />
US population of 1-3 per<br />
10000 (more common in<br />
taller athletes).<br />
Family history is a negative<br />
in approximately one-third<br />
of patients with Marfan<br />
syndrome (new mutation)<br />
A diagnosis of Marfan<br />
syndrome is based on<br />
clinical features as well as<br />
family history.
Common manifestations involve the<br />
skeletal, ophthalmologic, <strong>and</strong><br />
cardiovascular systems.<br />
Aortic root aneurysm rupture or<br />
dissection is the most common cause of<br />
sudden death.<br />
The aortic root dilatation starts at the<br />
sinuses of Valsalva <strong>and</strong> extends distally.<br />
MVP <strong>and</strong> MR typically occur when<br />
Marfan’s syndrome manifests in infancy.
Skeletal features include tall stature with<br />
arm span greater than height,<br />
arachnodactyly, hyperextensible joints,<br />
scoliosis, a high-arched palate, <strong>and</strong><br />
pectus excavatum. Ophthalmologic<br />
examination may show myopia <strong>and</strong> ocular<br />
lens subluxation, <strong>and</strong> echocardiography<br />
may reveal a dilated aortic root or MVP.<br />
Patients with suggestive physical features<br />
or a family history of Marfan syndrome<br />
may undergo clinical <strong>and</strong><br />
echocardiographic evaluation or DNA<br />
testing to confirm the diagnosis.
Diagnosis<br />
Positive family history:<br />
Two organ systems’ involvement with at least<br />
one major manifestation (such as lens<br />
dislocation, cystic medial necrosis of the aorta<br />
resulting in aortic dilatation/ aortic dissection,<br />
or the CNS abnormality, dural ectasia.<br />
Negative family history:<br />
Skeletal features are required in addition to two<br />
of the major manifestations listed above.
Exclusion from contact sports. Patients<br />
with aortic regurgitation <strong>and</strong> marked<br />
dilatation of the aorta are excluded from<br />
all competitive sports. Others may<br />
participate in low-intensity sports, with<br />
biannual echocardiography.
Commotio cordis or cardiac<br />
concussion<br />
Commotio cordis is an electrophysiological event<br />
caused by precordial chest impact that occurs in<br />
individuals free from structural cardiac disease.<br />
The mechanism of SCD appears to be ventricular<br />
fibrillation that is produced when the chest impact<br />
is delivered within a narrow, electrically vulnerable<br />
period of the cardiac cycle.<br />
Specifically, the susceptible time is during<br />
repolarization, 10–30 msec before the peak of the<br />
T wave.<br />
Resuscitation of these victims is possible with<br />
prompt CPR <strong>and</strong> defibrillation.
Medications<br />
proarrhythmic drugs such as epinephrine,<br />
ephedrine, cocaine, <strong>and</strong> related<br />
sympathetic medications<br />
performance-enhancing agents such as<br />
erythropoietin <strong>and</strong> anabolic steroids<br />
Anabolic steroids may cause cardiac<br />
hypertrophy, myocardial fibrosis, <strong>and</strong><br />
accelerated atherosclerosis that could<br />
promote cardiac necrosis <strong>and</strong> ischemia.
Exposure to agents such as erythromycin,<br />
antihistamines <strong>and</strong> phenothiazines,<br />
especially during antifungal treatment with<br />
‘conazole’ type agents, favours the<br />
development of torsade de pointes.<br />
Many reported clinical cases of<br />
myocardial infarction have been<br />
associated with cocaine<br />
A link between alcohol (ethanol) <strong>and</strong><br />
arrhythmogenic SCD has also been<br />
discussed.
Emergency physicians should<br />
maintain a high index of suspicion<br />
when syncope or near- syncope<br />
occurs in the presence of exercise.<br />
Exertional syncope is a distinct red<br />
flag <strong>and</strong> all patients with this<br />
symptom should be excluded from<br />
participation until they have a<br />
complete cardiac evaluation.
Preventive Strategies<br />
American approach<br />
European approach
The 12-Element AHA recommendations<br />
for preparticipation Cardiovascular<br />
Screening of Competitive Athletes<br />
Medical history<br />
Personal history<br />
1. Exertional chest pain/discomfort<br />
2. Unexplained syncope/near-syncope (not<br />
neurocardiogenic or vasovagal)<br />
3. Excessive exertional <strong>and</strong> unexplained<br />
dyspnea/fatigue, associated with exercise<br />
4. Prior recognition of a heart murmur<br />
5. Elevated systemic blood pressure
Family history<br />
6. Premature death (sudden <strong>and</strong> unexpected, or<br />
otherwise) before age 50 years due to heart<br />
disease, in 1 relative<br />
7. Disability from heart disease in a close relative<br />
50 years of age<br />
8. Specific knowledge of certain cardiac conditions<br />
in family members: hypertrophic or dilated<br />
cardiomyopathy, long-QT syndrome or other ion<br />
channelopathies, Marfan syndrome, or clinically<br />
important arrhythmias.
Physical examination<br />
9. Heart murmur (both supine <strong>and</strong> st<strong>and</strong>ing<br />
positions)<br />
10. Femoral pulses to exclude aortic<br />
coarctation<br />
11. Physical stigmata of Marfan syndrome<br />
12. Brachial artery blood pressure (sitting<br />
position <strong>and</strong> Preferably in both arms)
Prehospital Care<br />
Time period between witnessing <strong>and</strong><br />
initial defibrillation less than 2-3 min:<br />
survival rate ~ 50% .<br />
4-5 min: 25% or less<br />
After 10 min: less than 10%.
Management of Sudden<br />
Cardiac Arrest<br />
The initial components of SCA management are early<br />
activation of EMS, early CPR, early defibrillation, <strong>and</strong><br />
rapid transition to advanced cardiac life support<br />
(ACLS).<br />
Sudden cardiac arrest should be suspected in any<br />
collapsed <strong>and</strong> unresponsive athlete.<br />
An AED should be applied as soon as possible on any<br />
collapsed <strong>and</strong> unresponsive athlete for rhythm<br />
analysis <strong>and</strong> defibrillation if indicated.<br />
Cardiopulmonary resuscitation should be provided<br />
while waiting for an AED.<br />
Interruptions in chest compressions should be<br />
minimized <strong>and</strong> CPR stopped only for rhythm analysis<br />
<strong>and</strong> shock.
Cardiopulmonary resuscitation should be resumed<br />
immediately after the first shock, beginning with chest<br />
compressions, with repeat rhythm analysis after every 2<br />
minutes or 5 cycles of CPR, <strong>and</strong> continued until advanced<br />
life support providers take over or the victim starts to<br />
move.<br />
Sudden cardiac arrest in athletes can be mistaken for other<br />
causes of collapse, <strong>and</strong> rescuers should be trained to<br />
recognize SCA in athletes with special focus on potential<br />
barriers to recognizing SCA, including inaccurate rescuer<br />
assessment of pulse or respirations, occasional or agonal<br />
gasping, <strong>and</strong> myoclonic jerking or seizure-like activity.<br />
Young athletes who collapse shortly after being struck in<br />
the chest by a firm projectile or by player contact should<br />
be suspected of having SCA from commotio cordis.<br />
Rapid access to the SCA victim should be facilitated for<br />
EMS personnel.
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