Syncope: a benign condition? (Part 2)

Introduction
Investigations
Management
Cardiac syncope
Complications of syncope
Syncope and driving
Prognosis
Conclusion
References

This is part 2 of a two-part article.

Part 1 can be found here. 

 

 

 

Introduction

Syncope is defined as a sudden, but brief loss of consciousness caused by inadequate perfusion to the brain. It is usually benign, but it could also be suggestive of other underlying pathology hence proper investigation of a presentation of syncope is important.

Various conditions can present with syncope-like episodes and it is important to make a distinction between actual syncope and other presentations such as seizures, or cardiac arrest (Table 1).

TABLE 1: DIFFERENTIALS OF DISORDERS WITH OR WITHOUT LOSS OF CONSCIOUSNESS
Disorders with partial or complete LOC but with global cerebral hypoperfusion	Disorders without impairment of consciousness
Epilepsy	Cataplexy
Metabolic disorders including hypoglycaemia, hypoxia, hyperventilation with hypocapnia	Drop attacks
Intoxication	Falls
Vertebrobasilar TIA	Functional (psychogenic pseudosyncope)
	TIA or Carotid origin

Investigations

Blood pressure (including orthostatic), BM, ECG and possibly cardiac monitoring are usually the minimum requirements for the initial stage of investigation. Other investigations may be requested such as echocardiogram, neurologic studies, tilt table testing etc, and these are based on the results of the initial evaluation. A variety of tests, mostly cardiologic, can be used in the evaluation of the patient with syncope. Neurologic testing is generally of low yield and over-used, unless specifically suggested by history or physical examination. The 2009 ESC guidelines recommended the following testing strategy:

• Carotid sinus massage in patients >40 years old. Carotid sinus massage is diagnostic if syncope is reproduced together with a systolic drop longer than three seconds and/or a fall in systolic blood pressure >50mmHg
• Echocardiogram when there is previous known heart disease or data suggestive of structural heart disease or syncope secondary to cardiovascular cause
• Immediate ECG monitoring when there is a suspicion of arrhythmic syncope
• Orthostatic challenge (lying to standing orthostatic test or head-up tilt testing) when syncope is related to the standing position or there is suspicion of a reflex mechanism
• Other less specific tests such as neurological evaluation or blood tests are indicated only when there is suspicion of non-syncopal transient loss of consciousness.

 

Orthostatic challenge

The 2009 ESC syncope guidelines describe two methods for assessing the response to change in posture from supine to erect: active standing and tilt testing.

 

Active standing

Orthostatic blood pressure measurement is performed with the patient standing after at least five minutes of lying supine. Blood pressure should be measured each minute (or more often) in the standing position for three minutes or more (or as long as the patient tolerates) until the blood pressure nadir is reached.

 

Tilt testing

Tilt testing is commonly performed for the evaluation of syncope, although the test has limited specificity, sensitivity, and reproducibility.

 

Continuous 24 to 48-hour (Holter) monitoring

The value of 24 to 48-hour cardiac continuous monitoring is limited due to the intermittent nature of syncope. In general, such ambulatory monitoring appears to establish a diagnosis in only 1–3% of patients with syncope.

 

External event recorder

External event recorders appear to be somewhat more helpful than short-term continuous ambulatory monitoring in diagnosing the aetiology of syncope or presyncope. The 2009 ESC guidelines suggested that an external loop recorder may be indicated for patients who have clinical or ECG features, suggesting arrhythmic syncope.

 

Implantable loop recorder

The implantable loop recorder (ILR) is a subcutaneous monitoring device for the detection of cardiac arrhythmias. Such a device is typically implanted in the left parasternal or pectoral region and has a battery life of 18–24 months. The ILR may be most useful inpatients with infrequent symptoms and a suspected arrhythmia in whom non-invasive testing is negative or inconclusive.

 

Electrophysiology study

Electrophysiology study (EPS) is indicated in selected patients with unexplained syncope, particularly those with structural heart disease.

 

Indications for EPS

As noted in the 2009 ESC syncope guidelines, EPS is recommended in the following clinical settings. In patients with ischaemic heart disease, EPS is recommended when initial evaluation suggests anarrhythmic cause of syncope. In patients with bundle branch block, EPS should be considered when non- invasive tests have failed to make the diagnosis.

 

Management

Management of syncope is dependent on the underlying cause. The mainstay of managing neurally mediated syncope is reassurance and patient education. If syncope is frequent and occurs in high risk scenarios, or if it is not responding to conservative measures, some treatment options may be considered such as tilt training, cardiac pacing, isometric counter pressures and some medications eg. fludrocortisone and midodrine (although current evidence does not support the use of medications in neurally mediated syncope). If a patient has neurally mediated syncope secondary to carotid sinus hypersensitivity, then pacing is indicated for cardiac pauses greater than three seconds.

 

Orthostatic syndromes

The simplest measures are: to stop the offending drug, avoid alcohol, increase water intake especially prior to activities likely to increase orthostatic stress, raising the head of the bed, support stockings or abdominal binders and medications such as fludrocortisone (increases sodium concentration hence blood volume) or midodrine (increases vascular tone and elevates blood pressure). Droxidopa has also recently been in use, although not currently in the UK.

 

Cardiac syncope

Antiarrhythmic drugs, pacemakers or electrophysiological studies with ablation may be considered.

 

Postural hypotension

Once again reassurance and patient education are the mainstays of management. Individuals are advised to avoid triggers or remove the offending agents such as diuretics, antihypertensives etc. In addition, lifestyle and dietary modifications can be made, which include: increased salt and water intake, minimising alcohol intake, avoiding larger meals, slowly rising from a supine position, custom fitted elastic stockings, slightly tilting the head of the bed etc. Some pharmacological methods can also be employed. Currently, fludrocortisone and midodrine are most commonly in use and ivabradine is also recently in use.

 

Complications of syncope

Complications of syncope range from none (mostly with neurally mediated syncope) to death (commonly with cardiac syncope). Physical injury can result from syncope, and even more seriously, syncope has been found to be the cause of about 21% of road accidents involving loss of consciousness at the wheel, second only to epilepsy.

 

Syncope and driving

Guidance from the DVLA applies to transient loss of consciousness (TloC) in general and useful guidelines can be found on their website, a summary of which is found in figure 2.

 

FIGURE 2: TLOC-SOLITARY EPISODE (TAKEN FROM DVLA WEBSITE)
	Group 1 car and motorcycle	Group 2 Bus and lorry
Typical vasovagal syncope with reliable prodrome
While standing	■ May drive and need not notify the DVLA	● Must not drive and must notify the DVLA
While sitting	▲ May drive and need not notify the DVLA if there is an avoidable trigger which will not occur whilst driving. Otherwise must not drive until annual risk of recurrence is assessed as below 20%.	● Must not drive for 3 months
Syncope with avoidable trigger or reversible cause (see cough syncope)
While standing	■ May drive and need not notify the DVLA	● Must not drive and must notify the DVLA
While sitting	● Must not drive for 4 weeks Driving may resume after 4 weeks only if the cause has been identified and treated. Must notify the DVLA if the cause has not been identified and treated.	● Must not drive for 3 months Driving may resume after 3 months only if the cause has been identified and treated. Must notify the DVLA if the cause has not been identified and treated.
Unexplained syncope, including syncope without reliable prodrome
This diagnosis may apply only after appropriate neurological and/or cardiological opinion and investigations have detected no abnormality.
While standing or sitting	● Must not drive and must notify the DVLA If no cause has been identified, the licence will be refused or revoked for 6 months.	● Must not drive and must notify the DVLA If no cause has been identified, the licence will be refused or revoked for 6 months.
Cardiovascular, excluding typical syncope
While standing or sitting	● Must not drive and must notify the DVLA Driving may be allowed to resume after 4 weeks if the cause has been identified and treated. If no cause has been identified, the licence will be refused or revoked for 6 months.	● Must not drive and must notify the DVLA Driving may be allowed to resume after 3 months if the cause has been identified and treated. If no cause has been identified, the licence will be refused or revoked for 12 months.

 

Prognosis

Prognosis of syncope is largely dependent on the aetiology. Poorer outcomes are more often associated with underlying cardiac disease, associated with ECG changes, family history or increasing age. Younger patients carry a better prognosis as it is mostly benign in this group.

 

Conclusion

Syncope is mostly benign, but even the most benign forms of syncope can have significant consequences for the individual. Thorough assessment of patients with syncope is essential both in primary and secondary care, not only to aid in its management but also assess those at higher risk and those who may benefit from specialist investigation or assessment. Various risk scores can be applied to help make clinical decisions. If the syncopal episode does not fit all of the following: complete, transient loss of consciousness with short duration and rapid onset, spontaneous recovery, absence of sequelae and loss of postural tone, then other causes of the presentation must be considered.

 

Dr A Ntrakwah, Foundation Year 2
Dr U. Fernando, Consultant Physician
Elderly Care, Walsall Manor Hospital

Conflict of interest: none declared

 

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References

1. Reflex syncope in adults: Clinical presentation and diagnostic evaluation. (n.d.). Retrieved March 15, 2017, from https://www.uptodate.com/contents/reflex-syncope?source=see_ link#H26

2. Payne, D. J. (2015, March 12). Syncope | Doctor. Retrieved March 15, 2017, from http://patient.info/doctor/syncope

3. Drugs and pacemakers for vasovagal, carotid sinus and situational syncope. (n.d.). Retrieved March 15, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/21975744?dopt=Abstract-loss-of-consciousness/ initial-assessment-for-transient-loss-of-consciousness.xml&content=view-index

4. ESC Clinical Practice Guidelines. (n.d.). Retrieved March 15, 2017, from http://www.escardio.org/Guidelines/Clinical- Practice-Guidelines/Syncope-Guidelines-on-Diagnosis-and-Management-of

5. Approach to the adult patient with syncope in the emergency department. (n.d.). Retrieved March 15, 2017, from https://www.uptodate.com/contents/approach-to-the-adult-patient- with-syncope-in-the-emergency-department?source=search_ result&search=syncope&selectedTitle=2~15