This document discusses sudden cardiac death and arrhythmias in athletes. It provides information on: 1) The most common causes of exercise-related sudden death depend on age, with hypertrophic cardiomyopathy being the most common in young athletes under 35 years old. 2) While the risk of sudden death from exercise is low in healthy adults, it increases with certain cardiac conditions like coronary artery disease, structural heart diseases, and inherited arrhythmia syndromes. 3) Evaluation of athletes with arrhythmias or syncope requires careful examination, testing like ECGs, echocardiograms, and exercise testing to determine the cause and risk level to guide management decisions around activity restriction.

2. Sudden Cardiac Death (SCD) and
Arrhythmias in Athletes
Dr Fiona Foo
MBBS (hons) FRACP
General and Interventional
Cardiologist

3. What is the most frequent cause of
exercise related sudden death?
• A) Coronary artery disease
• B) Hypertrophic Obstructive
Cardiomyopathy (HOCM)
• C) Right ventricular Cardiomyopathy
(RVCM)
• D) All of the above

4. Depends on age…
• In the ‘Young” <35years old
• In ‘Adults’ - coronary artery disease is the
predominant cause of SCD during
exercise.

5. Most MIs are Caused by Lesions of
Minimal Stenosis

6. How dangerous is exercise for
Healthy Adults?
1 Death per year Per
Thompson
JAMA 217: 2535, 1982
15 640
Siscovick
NEJM 311: 871, 1984
18 000

7. SCA/Sudden death amongst
athletes
Long distance runners SCA 1/184000
Sudden death 1/259000
(0.2 cardiac arrests and 0.14
sudden deaths per 100000 runner
hours at risk)
Collegiate athletes 1 death per 43770 participants per
year
Triathlon participants 1 death per 52 630 participants per
year
Healthy middle aged joggers 1 death per 7620 participants

8. Structural Heart Disease
• SCD in athletes often occurs in the presence of structural heart
disease.
• Structural heart disease can increase the risk for SCD by one or
more of the following mechanisms:
i) Ventricular tachyarrhythmias (dt reentrant arrhythmias that
develop in abnormal myocardium +/- areas of fibrotic replacement
of myocardial tissue)
ii) Bradyarrhythmia or asystole (dt extension of the pathologic
process into the conduction system, causing complete heart
block)
iii) Syncope in addition to the other arrhythmic causes
iv) Dissection of the great vessels (eg marfans)
* In the Majority of conditions ventricular tachyarrhythmias are the
most common cause of SCD

9. Cardiovascular causes of sudden
death in 1435 young (<35yo)
competitive athletes
Maron, Thompson et al Circulation 2007

10. Italian Experience - 49 athletes
under age 35 with SCD
• Arrhythmogenic right ventricular
Cardiomyopathy 22%
• Coronary atherosclerosis 18%
• Anomalous origin of a coronary artery
12%
• Mitral valve prolapse 6%
• Myocarditis 6%
• HOCM 2%

11. SCD in the absence of structural
heart disease
• Long QT syndrome
• Brugada syndrome
• Cathecholaminergic polymorphic ventricular
tachycardia (CPVT)
• Commotio cordis (SCD results from being struck
in the precordium with a projectile object)
• Idiopathic VF (primary electrical disease)

12. HOCM…
• Most common cardiac abnormality found in athletes with
SCD
• Need to distinguish from physiological changes due to
training
• Patients with HOCM – stratification can identify patients
at high/low risk for SCD, however even patients with no
risk factors are at some risk
• Risk stratification: cardiac arrest, fhx of SCD, syncope,
Extreme LVH (>3mm wall thickness), hypotensive BP
response to exercise, nonsustained VT on
holter….others

13. Congenital coronary anomalies
• 12-33% of young athletes with SCD
• Most common anomalies are 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
• High risk anomalies are those in which the anomalous coronary
artery makes an acute bend and courses between the pulmonary
artery and aorta –
- presumed mechanism of SCD involves ischaemia secondary to an
exaggeration of a sharp angle in the aberrant origin that occurs with
exercise, especially as the artery traverses an expanded aorta and
pulmonary arterial trunk.
• Patients may present with anginal chest pain, syncope or
presyncope especially with exercise though SCD is often the first
presentation.

14. Congenital coronary anomalies

15. Arrythmogenic Right Ventricular
Cardiomyopathy (ARVC)
• Fibrofatty infiltration of the right ventricular (RV)
myocardium, predominately in the free wall
• May present with exercise induced palpitations,
presyncope/syncope
• Mechanism? catecholamine sensitive nature of the
associated tachyarrhythmias, and wall stretch observed
in the right heart in response to the increased venous
return during exercise

16. ARVC

17. Marfan Syndrome
• Most common inherited disorder of connective
tissue
• Autosomal dominant condition
• 1/10000-20000
• Arachnodactyly, tall structure, pectus
excavatum, kyphoscoliosis, lenticular dislocation
• Aortic dissection --- leads to sudden death

18. Aortic dissection

19. Myocarditis
• 6-7% of SCD in competitive athletes
• Clinical findings of heart failure in an otherwise healthy
young person, ECG signs (diffuse repolarisation
abnormalities), +/- global/regional wall motion
abnormalities 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
for SCD, this risk may be proportional to the degree of
cardiac dysfunction

21. Mitral Valve Prolapse
• Occurs freq in general population.
• Relationship between MVP, tachyarrhythmias
and SCD is controversial
• Isolated MVP w/o MR risk of SCD is low 2/10000
per year
• Patients with MVP with significant mitral valve
pathology or MR are at increased risk of SCD - ?
0.9-1.9%

23. Long QT

24. Long QT
• Congenital Long QT
• Numerous ion channel mutations
• LQTS 1,2 and 3 account for 90% of cases
• Arrhythmogenic events triggered by
exercise are much more common in
LQTS1 than in LQTS 2+3

26. Brugada syndrome
• RBBB and ST segment elevation in V1-V3
• Increased risk of sudden death.
• Ages 22-65 and arrhythmic events
generally are more common at night/sleep
than awake; not often related to exercise.

28. SCD - summary
• SCD associated with athletic activity is a rare but
devastating event
• The incidence of SCD amongst competitive athletes
estimated 1/50000 - 1/300000
• The majority of SCD events in athletes are due to
malignant arrhythmias, usually VT/VF
• The potential aetiologies of SCD include structural heart
disease, inherited arrhythmia syndromes and coronary
heart disease, the exact distribution varies according to
age and geography
• Some levels of activity restriction is recommended for
nearly all individuals with underlying heart disease

29. Arrhythmias in Athletes
• Arrhythmias are not infrequently
documented in athletes
• Presentation: no symptoms, palpitations,
decreased exercise tolerance, syncope,
cardiac arrest
• Many causes and underlying conditions
make mx and restriction a challenge

30. Screening - 2 goals
1. To document the presence of an
arrhythmia and underlying structural
heart disease that place the athlete at
risk for sudden death
2. To evaluate the importance of an
arrhythmia in assessing the athletes
eligibility for competition

31. Spectrum of arrythmias
• Syncope
• Sinus bradycardia/sinus tachycardia
• Atrial premature beats
• Atrial fibrillation/Atrial flutter
• AVNRT, WPW and AVRT
• Ventricular premature beats
• VT
• Long QT

32. Syncope
• Loss of consciousness, faint, loss of postural
tone.
• Requires thorough evaluation
• Some common Causes:
1. Cardiac - arrhythmic, LV obstruction
2. Neurocardiogenic
3. Neurological
4. Volume/vascular tone
5. Pulmonary embolism
6. Hypoglycaemia
7. Psychogenic

33. Syncope in athletes
• Neurally mediated (vasovagal) syncope
unassociated with cardiac disease is a common
cause of syncope in young athletes
• Hypovolemia from unreplaced fluid losses may
contribute
• Athletes (esp those engaged in endurance
disciplines) may be more susceptible to neurally
mediated syncope by nature of their increased
vagal tone

34. Syncope in athletes
• Underlying structural heart disease should be
eliminated before considering neurally mediated
syncope as the etiology
• Pathologic cardiac causes of exertional syncope:
VT and obstruction from HCOM/AS,
Hypotension due to vagally mediated
vasodepression in patients with HCOM
• DDX of exertional syncope: exertional heat
stroke/hyperthermia, exertional hyponatraemia

35. Clinical characteristics
Neurocardiogenic
or non arrhythmic
Arrhythmic
Prodrome
Number of
episodes
Lightheadedness,
warmth, nausea
Multiple
Non or brief
lightheadedness
Few or 1
Situational factors Fear, upright
posture,
Exertional,
unrelated to
posture
Postsyncopal Sx Frequently fatigue Usually none
Injury Unusual Common
Underlying heart
disease
Unusual Common

36. What is more concerning??
 Syncope whilst running down a basketball
court
OR
 Syncope during a time out?

37. Concerning symptoms
• Preceding symptoms brief
• First episode later in life
• Underlying cardiac disease
• Non-Orthostatic syncope
• Exertional
• Injury

38. Syncope and athletes
• Report of 7568 young athletes, mean age 16years
• 474 (6.2%) reported a syncopal spell in the preceding 5
years
• Syncope was unrelated to exercise in 411 (87%),
postexertional in 57 (12%) and exertional in 6 (1%)
• All episodes of nonexertional or postexertional syncope
were diagnosed as vasovagal, situational or
postexertional postural hypotension
• In 6 patients with exertional syncope: 1 had HOCM, 1
RVOT tachycardia, 4 cases of neurocardiogenic syncope

39. Evaluation…
• History, examination
• ECG
• Exercise testing to replicate the clinical scenario
• Holter monitoring during the sport
• ECHO in all patients
• Electrophysiology studies in those with
underlying cardiac disease/no cause for the
syncope has been established.
• (Neurology consult, Head CT)

40. Arrythmias in athletes
• Sinus bradycardia is common in a well trained athlete -
increased vagal tone by exercise conditioning +/-
alteration in the intrinsic property of the SA and AV node.
• Sinus arrhythmia also common dt increased vagal tone
• Asymptomatic sinus pauses <3s are probably normal
in athletes and of no clinical significance, but longer
pauses, sinoatrial block or sick sinus syndrome are
abnormal
• Atrial premature beats are common in the general
population and athletes, are not generally associated with
underlying structural heart disease,

41. Atrial Flutter
• Atrial flutter in the absence of WPW is
uncommon in athletes
• If present and no structural heart disease-
should be offered ablation (potential for
1:1 AV nodal conduction and rapid
ventricular rates)

43. Atrial Fibrillation
• Common (?up to 8times general population), in
young athletes may occur in the absence of
structural heart disease or other provoking
conditions (lone AF) in older athletes -
hypertension and coronary artery disease are
common
• Look for Cause of AF
• Can be very symptomatic, rate control difficult as
antiarrhythmics may not work at peak exercise
• Risks of anticoagulation…
• Ablation effective

45. Atrioventricular Nodal Reentrant
tachycardia (AVNRT)
• Can be common in young athletes and often associated
with symptoms.
• Those who have syncope, presyncope, palpitations or
evidence of hemodynamic compromise due to the
AVNRT or have structural heart disease should not
participate in any sport until they have been adequately
treated and have no recurrence for 2-4 weeks
• Athletes w/o structural heart disease who undergo
successful catheter or surgical ablation who are
asymptomatic or have no inducible AVNRT on follow up
EPS testing or no recurrence of arrhythmia for 2-4 weeks
can participate in all sports

46. 18yo M collapse during basketball, frequent palpitations
with basketball, negative treadmill
ECG in ED…

47. AF----cardiac arrest

48. Wolff-Parkinson-White Syndrome
• Ventricular pre-excitation on the surface ecg with
associated tachycardia - WPW syndrome
• Most common arrhythmia is an atrioventricular reentrant
tachycardia (AVRT): narrow qrs when ventricular
activation or antegrade conduction is via the normal AV
node-his purkinje system (orthodromic AVRT) or less
commonly a wide QRS complex when ventricular
activation is via the accessory pathway (antidromic
AVRT)
• SCD dt VF in patients with WPW is rare - confined to
patients with AF or atrial flutter and rapid conduction to
the ventricles via a bypass tract which has a particularly
short functional refractory period

49. WPW syndrome
• Asymptomatic - ?induce AF/invasive EP testing
to characterise the bypass tract properties and
establish the presence of a tract with a short
refractory period
• Those with symptoms of palpitations,
syncope/presyncope or with documented
arrhythmia should have EP testing to assess the
refractory period of the accessory connection
and the shortest and mean RR interval during
sustained preexcited AF
• If the ventricular rate during preexcited AF is
>240b/min; - radiofrequency catheter ablation

52. Ventricular Ectopics
• Ventricular premature beats are common in
athletes of all age groups and can occur with or
without structural heart disease
• Their presence is not a risk factor for a sustained
VT or sudden death, but their prognostic
importance is based upon an association with
underlying structural heart disease
• 12 lead ecg, 24hour holter to assess complexity
and frequency; and if suspicion of structural
heart disease - echo and EST

54. VT
• Most fit individuals who present with
sustained or nonsustained symptomatic
monomorphic or polymorphic VT have
underlying structural heart disease
• Requires evaluation with ecg, holter,
exercise testing, echo, cardiac MRI +/-
coronary angiogram/EPS

56. Arrhythmias in athletes
• Athletes with arrhythmias require careful
evaluation
• Large number of causes and underlying
conditions make management a challenge
• Restriction of activity depends on cause,
risk, treatment and chances for recurrence