Guidelines for the Management of Syncope M. B

Guidelines for the Management of Syncope

M. B

Syncope is a transient, self-limited loss of consciousness usually leading to a fall, due to transient global cerebral hypoperfusion. Causes of syncope are:

- Neurally mediated (reflex) syncopal syndromes - Orthostatic

- Cardiac arrhythmias (as primary cause) - Structural cardiac or cardiopulmonary disease

First of all, syncope must be differentiated from other ‘non-syncopal’ con- ditions associated with real or apparent transient loss of consciousness such as, for example, metabolic disorders, epilepsy, intoxication, transient ischaemic attacks (TIA), and psychogenic ‘syncope’.

Initial Evaluation

The initial evaluation is based on a careful history and physical examination including orthostatic blood pressure measurements. Other than in young patients without heart disease, a 12-lead ECG should usually be part of the general evaluation. Three key questions are:

- Is loss of consciousness attributable to syncope or not?

- Is heart disease present or absent?

- Are there important clinical features in the history that suggest the diagnosis?

History and Physical Examination Questions should be asked about:

- Circumstances just prior to the attack: body position, activity, predispos- ing factors, and precipitating events

Department of Cardiology and Arrythmologic Centre, Ospedali del Tigullio, Lavagna

(Genua), Italy

- Onset of the attack: nausea, vomiting, abdominal discomfort, feeling of cold, sweating, aura, pain in neck or shoulders, blurred vision

- Attack (eyewitness): manner of the fall, skin colour, duration of loss of consciousness, breathing pattern, movements and their duration, onset of movement in relation to fall, tongue biting

- End of attack: nausea, vomiting, sweating, feeling of cold, confusion, mus- cle aches, skin colour, injury, chest pain, palpitations, urinary or faecal incontinence

- Background: family history, cardiac and neurological history, metabolic disorders, medication, information about previous syncope

Physical findings that are useful in diagnosing syncope include cardio- vascular and neurological signs and orthostatic hypotension. The presence of a murmur or severe dyspnoea is indicative of structural heart disease and of a cardiac cause of syncope.

Baseline Electrocardiogram

A normal ECG (most common finding) is associated with a low probability of cardiac syncope as the cause. When abnormal, the ECG may disclose an arrhythmia associated with a high likelihood of syncope, or an abnormality which may predispose to arrhythmia development and syncope.

Abnormalities suggesting an arrhythmic syncope are:

- Bifascicular block or other intraventricular conduction abnormalities (QRS duration > 0.12 s)

- Mobitz I second-degree atrioventricular block

- Asymptomatic sinus bradycardia (< 50 beats/min) or sinoatrial block - Pre-excited QRS complexes

- Prolonged QT interval

- Right bundle branch block pattern with ST elevation in leads V1-V3 (Brugada syndrome)

- Negative T waves in right precordial leads, epsilon waves, and ventricular late potentials suggestive of arrhythmogenic right ventricular dysplasia - Q waves suggesting myocardial infarction

Definitive Diagnosis

Initial evaluation may lead to a definite diagnosis (no further evaluation may be needed and treatment can be planed), in the following situations:

- Vasovagal syncope: if precipitating events such as fear, severe pain, emo- tional distress, instrumentation or prolonged standing are associated with typical prodromal symptoms

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359 Guidelines for the Management of Syncope

- Situational syncope: if syncope occurs during or immediately after urina- tion, defecation, cough, or swallowing

- Orthostatic syncope: when there is documentation of orthostatic hypoten- sion associated with syncope or presyncope. A decrease in systolic blood pressure > 20 mmHg or a decrease of systolic blood pressure to < 90 mmHg measured after 1 or 3 min of standing is defined as orthostatic hypotension regardless of whether or not symptoms occur

- Cardiac ischaemia-related syncope: when symptoms are present with ECG evidence of acute ischaemia with or without myocardial infarction, inde- pendently of its mechanism

- Arrhythmia-related syncope in presence of the following ECG abnormali- ties:

- Sinus bradycardia < 40 beats/min or repetitive sinoatrial blocks or sinus pauses > 3 s in the absence of negatively chronotropic medica- tions

- Mobitz II second- or third-degree atrioventricular block - Alternating left and right bundle branch block

- Rapid paroxysmal supraventricular tachycardia or ventricular tachy- cardia

- Pacemaker malfunction with cardiac pauses

Unexplained Syncope

In the presence of structural heart disease or an abnormal ECG, cardiac eval- uation consisting of echocardiography, stress testing, and tests for arrhyth- mia detection such as prolonged electrocardiographic and loop monitoring or electrophysiological study is recommended.

If cardiac evaluation does not show evidence of arrhythmia as a cause of syncope, evaluation for neurally mediated syndromes is recommended in patients with recurrent or severe syncope.

In patients without structural heart disease and a normal ECG, evalua- tion for neurally mediated syncope is recommended for those with recurrent or severe syncope.

Reappraisal

When no cause of syncope can be determined, reappraisal of the work-up is

needed since subtle findings or new historical information may change the

entire differential diagnosis.

References

1. Brignole M, Alboni P, Benditt D et al (2004) Guidelines on management (diagnosis and treatment) of syncope – update 2004. Europace 6:467–537

2. Brignole M, Alboni P, Benditt D et al (2004) Guidelines on management (diagnosis and treatment) of syncope – update 2004 – executive summary and recommenda- tions. Eur Heart J 25:2054–2072

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