Strategic Approach - Syncope in Young Adults (18-35 years of age)

The approach to the assessment of any patient with syncope is influenced by the age of the patient and the presentation of the events. Here we discuss the likley causes and an approach to assessment. Indications for specialist referral are also indicated.

Likely Causes

Syncope first presenting in the young adult is most likely to be neurally mediated in origin:

• Early post puberty, up to the early thirties, are the most common years for neurally mediated syncope to first present.
  • Age 15 is the most common age for neurally mediated syncope to first present.
• It is important to be aware that young patients with neurally mediated syncope not uncommonly have brief seizure like movements in association with syncope due to the profound drop in blood pressure and heart rate (including periods of asystole) that occurs with this form of syncope.

Uncommonly supraventricular tachycardia can present with syncope in this age group.

• Supraventricular tachycardia resulting in syncope is generally the result of initiation of a neurally mediated syncopal response due to the tachycardia.

Rarely more serious hereditary causes of syncope may also present in this age group and should be considered:

• Long QT syndrome
• Hypertrophic Cardiomyopathy
• Arrhythmogenic Right Ventricular Dysplasia
• Brugada Syndrome
• Catecholaminergic Polymorphic Ventricular Tachycardia

These conditions may all present with syncope during early adult life.

Rarely left ventricular dysfunction due to a dilated cardiomyopathy or premature coronary disease can present with syncope in this age group as a result of ventricular arrhythmias or hypotension due to low cardiac output.

Congenital complete heart block and other primary bradyarrhythmias are rare causes of syncope in this age group.

Also consider:

Epilepsy may also first present in this age group but is a much less common disorder than syncope:

• 5% of the population will have a seizure at some time in their life with approximately 1% being diagnosed with epilepsy (two or more seizures).
• Approximately 50% of patients with epilepsy have ‘partial’ seizures that in general do not result in the person falling to the floor with generalized seizure movements.
• In contrast - syncope will occur in up to 25% of the population and up to 38% of women at some time in their life.

Psychogenic syncope:

Can present in this age group. This is a diagnosis of exclusion.

This diagnosis should be considered in patients in whom recurrent events occur in a pattern not consistent with neurally mediated syncope and standard evaluation including tilt table testing is negative. If the pattern of events is consistent with a neurally mediated mechanism then a negative tilt test does not exclude neurally mediated syncope as a diagnosis.

When assessing ECG data alone (eg Holter monitors) it is important to look for heart rate fluctuations that may suggest a neurally mediated cause with predominant hypotension.

Patients with psychogenic epssodes. may have co-existant neurally mediated syncope occuring at other time which can be treated with simple measures.

Hyperventilation in association with anxiety or panic attacks can on occasion be implicated.

Management of these patients is complex and a combined medical and psychological approach is usually required.

 

Approach to the Young Adult with Syncope:

Syncope is most likely the result of a benign cause – Neurally Mediated Syncope - if:

• There is no family history of inherited cardiac disorders or sudden unexpected sudden.
• The patient does not have a history of heart disease
• There is a family history of Neurally Mediated Syncope
• The ECG is normal

And the episodes occurred in ‘typical’ circumstances:

• Prolonged standing or sitting in a warm environment
• After exercise
• In association with vaccination, venesection.
• At the sight of blood
• After sudden change in posture.

These episodes are often preceded by warning signs of:

• Heat,
• Nausea,
• Sweating,
• Blurred vision

During the event the patient will usually appear:

• pale
• clammy
• brief seizure like movements (lasting < 1 min) may occur

Recovery:

• is usually quick but not instantaneous
• there is usually a period of lethargy following the event
• patients may be aware of a sinus tachycardia pre or post the event.
• patients may vomit after the event

Investigation of a 'typical' Neurally Mediated Syncopal Event:

• All syncopal patients must have:
  • a cardiovascular examination (including lying and standing pulse and blood pressure)
  • an electrocardiogram (ECG) performed
• If these are both normal in the above circumstances no further investigation is required.

Further Investigations:

• An Echocardiogram may be performed.
  • It is rarely abnormal in these circumstances, but a normal echocardiogram together with a normal ECG indicates a very low risk of syncope having been due to a serious cause.
• Tilt table testing can be helpful for patient reassurance and education if typical events are recurrent.
• Holter monitoring is invariably unhelpful in this age group.

Simple Management

• Most of these patients can be reassured and given simple advice to increase salt and fluid intake.
  • For more detailed management go to Management - Neurally Mediated Syncope

 

Serious and potentially life threatening causes of syncope should be considered if:

• There is a family history of an inherited cardiac disorder or sudden unexpected death.
• The patient has a history of heart disease.
• The episode occurred during exercise, sleep or lying down.
• The episode occurred in association with a loud noise, a ‘surprise’, or swimming.
• The circumstances were not ‘typical’ for neurally mediated syncope.

Investigation:

• A cardiovascular examination and electrocardiogram (ECG) must always be performed.
• An echocardiogram should be arranged to assess for structural abnormalities of the heart.

These investigations may provide diagnostic evidence of one of the inherited conditions listed below:

• Long QT syndrome
• Arrhythmogenic Right Ventricular Dysplasia
• Brugada Syndrome
• Hypertrophic Cardiomyopathy

Further Investigation:

• Holter monitoring is rarely helpful in these conditions unless events are occurring daily.
• External Event ( Loop) Monitors are rarely helpful in these conditions unless episodes are occurring weekly.
• An Implantable Loop recorder can be used if event are recurrent and the cause is not determined by initial investigations.
• Exercise stress testing can be helpful in assessing for exercise induced arrhythmias or myocardial ischaemia if these are suspected.
• Provocative investigations may be performed if Brugada Syndrome is suspected and the baseline ECG is suggestive but not diagnostic.
• Cardiac Magnetic Resonance Imaging may be performed to further assess for cardiomyopathy, in particular Arrhythmogenic Right Ventricular Dysplasia.
• Invasive elctrophysiological studies may be performed to assess for inducible ventricular arrhythmias.

Patients presenting with syncope with any features suggestive of a serious cause of syncope should be referred for early assessment by a Cardiologist with expertise in these conditions (Cardiac Electophysiologist)