Sudden Cardiac Death (SCD) and Arrhythmias in Athletes

Dr Fiona Foo

MBBS (hons) FRACP

General and Interventional Cardiologist

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

Depends on age…

• In the ‘Young” <35years old

• In ‘Adults’ - coronary artery disease is the predominant cause of SCD during exercise.

Most MIs are Caused by Lesions of Minimal Stenosis

How dangerous is exercise for Healthy Adults?

1 Death per year Per

ThompsonJAMA 217: 2535, 1982

15 640

SiscovickNEJM 311: 871, 1984

18 000

SCA/Sudden death amongst athletes

Long distance runners SCA 1/184000Sudden 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

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 causesiv) Dissection of the great vessels (eg marfans)* In the Majority of conditions ventricular tachyarrhythmias are the most

common cause of SCD

Cardiovascular causes of sudden death in 1435 young (<35yo)

competitive athletes

Maron, Thompson et al Circulation 2007

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%

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)

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

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.

Congenital coronary anomalies

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

ARVC

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

Aortic dissection

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

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%

Long QT

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

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.

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

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

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

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

Syncope• Loss of consciousness, faint, loss of postural tone.• Requires thorough evaluation• Some common Causes:1. Cardiac - arrhythmic, LV obstruction2. Neurocardiogenic3. Neurological4. Volume/vascular tone5. Pulmonary embolism6. Hypoglycaemia7. Psychogenic

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

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

Clinical characteristicsNeurocardiogenic 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

What is more concerning?? Syncope whilst running down a basketball court

OR

Syncope during a time out?

Concerning symptoms

• Preceding symptoms brief

• First episode later in life

• Underlying cardiac disease

• Non-Orthostatic syncope

• Exertional

• Injury

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

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)

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,

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)

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

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

18yo M collapse during basketball, frequent palpitations with basketball, negative treadmill

ECG in ED…

AF----cardiac arrest

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

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

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

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

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