What is the initial workup for a patient presenting with syncope?

From the Guidelines

The initial workup for a patient presenting with syncope should include a thorough history, physical examination, and targeted diagnostic tests, starting with a careful history, physical examination including orthostatic blood pressure measurements, and standard electrocardiogram (ECG) as recommended by the guidelines 1. The diagnostic strategy based on the initial evaluation should focus on differentiating true syncope from ‘non-syncopal’ conditions associated with real or apparent transient loss of consciousness. Begin with a detailed history focusing on the circumstances surrounding the event, prodromal symptoms, position at onset, duration, recovery pattern, and any associated symptoms like chest pain or palpitations. Obtain a complete medication history, as drugs like antihypertensives, antiarrhythmics, and psychiatric medications can cause syncope. The physical examination should include orthostatic vital signs, a detailed cardiovascular exam including heart sounds and carotid bruits, and a neurological assessment. An electrocardiogram (ECG) is essential for all syncope patients to evaluate for arrhythmias, conduction abnormalities, or signs of structural heart disease, as stated in the guidelines 1. Some key points to consider in the initial evaluation include:

• Careful history and physical examination to identify potential causes of syncope
• Orthostatic blood pressure measurements to assess for orthostatic hypotension
• Standard electrocardiogram (ECG) to evaluate for arrhythmias or conduction abnormalities
• Laboratory tests, such as complete blood count, basic metabolic panel, and cardiac enzymes, if cardiac etiology is suspected
• Additional tests, such as echocardiogram, Holter monitoring, or tilt-table testing, based on clinical suspicion, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. Transthoracic echocardiography can be useful in selected patients presenting with syncope if structural heart disease is suspected, as recommended by the 2017 ACC/AHA/HRS guideline 1. However, routine cardiac imaging is not useful in the evaluation of patients with syncope unless cardiac etiology is suspected on the basis of an initial evaluation, including history, physical examination, or ECG, as stated in the guidelines 1. Neuroimaging (CT or MRI) is generally not recommended unless there are focal neurological findings or suspicion of seizure. This comprehensive approach helps identify the underlying cause of syncope, which is crucial for appropriate management, as syncope can range from benign conditions like vasovagal episodes to life-threatening cardiac arrhythmias. Some of the key recommendations from the guidelines include:
• Transthoracic echocardiography can be useful in selected patients presenting with syncope if structural heart disease is suspected (Class IIa, LOE B-NR) 1
• Computed tomography (CT) or magnetic resonance imaging (MRI) may be useful in selected patients presenting with syncope of suspected cardiac etiology (Class IIb, LOE B-NR) 1
• Routine cardiac imaging is not useful in the evaluation of patients with syncope unless cardiac etiology is suspected on the basis of an initial evaluation, including history, physical examination, or ECG (Class III, LOE B-NR) 1

From the Research

Initial Workup for Syncope

The initial workup for a patient presenting with syncope should focus on history, physical examination, and electrocardiography (ECG) examination 2.

Key Components of the Initial Workup

• History: A careful, well-conducted medical history focused on the suspected syncopal event is crucial for the diagnosis 3.
• Physical examination: Information obtained from physical examination should be used to guide the selection of further high-yield tests 2.
• Electrocardiography (ECG): A 12-lead ECG is the only instrumental test recommended for the initial evaluation of patients with suspected syncope 3. The ECG may disclose an arrhythmia associated with a high likelihood of syncope, avoiding further evaluations and permitting institution of specific treatment in some patients 3.

Further Testing

Further testing, such as Holter monitoring, head-up tilt table test (HUTT), treadmill test, CT/MRI of the brain, electroencephalography, carotid sinus massage, coronary angiography, electrophysiological study, and carotid Doppler ultrasound, may be performed based on the findings from medical history, physical examination, ECG, and echocardiography findings 2.

• Loop recorders have a much higher diagnostic yield for patients with syncope or presyncope as compared with Holter monitors 4.
• Electrophysiologic studies are more likely to be abnormal in patients with underlying heart disease or those who have abnormalities on surface electrocardiogram 5.
• Upright tilt testing has been used to induce vasovagal syncope in patients with syncope of unknown cause 5.

Importance of ECG

The ECG is a mandatory diagnostic tool which, although normal in the majority of patients with syncope, has the potential to identify patients with high likelihood of cardiac syncope due to arrhythmic or cardiopulmonary disorder 3. Certain electrocardiographic presentations in the patient with syncope will not only provide a reason for the loss of consciousness but also guide early therapy and disposition in this individual 6.