From the Guidelines
The workup for syncope should begin with a thorough history and physical examination, focusing on the circumstances surrounding the event, prodromal symptoms, and any associated features, as recommended by the 2021 ACR Appropriateness Criteria for syncope 1. The initial evaluation should include orthostatic vital signs, electrocardiogram (ECG), and basic laboratory tests (complete blood count, electrolytes, glucose, and renal function) to identify potential cardiac or non-cardiac causes of syncope.
- Key elements of the history include:
- Circumstances surrounding the event
- Prodromal symptoms
- Associated features such as palpitations, chest pain, or neurological symptoms
- The physical examination should focus on:
- Cardiac examination to assess for structural heart disease
- Neurological examination to exclude separate neurologic processes If cardiac causes are suspected, additional tests may include:
- Echocardiography
- Ambulatory cardiac monitoring (Holter or event monitor for 24 hours to 30 days depending on frequency of symptoms)
- Exercise stress testing in some cases For recurrent unexplained syncope, extended cardiac monitoring with implantable loop recorders may be warranted 1. Neurological evaluation with electroencephalogram (EEG) and brain imaging (CT or MRI) should be considered if seizure is suspected or if there are focal neurological findings, as these conditions require a different course of evaluation 1. Tilt-table testing can help diagnose vasovagal syncope when the history is unclear, and carotid sinus massage may be performed in older patients to evaluate for carotid sinus hypersensitivity, though this should be done with caution and cardiac monitoring 1. The diagnostic approach should be guided by the initial clinical assessment, as extensive testing in all patients is not cost-effective and may not yield significant findings, emphasizing the importance of a targeted approach based on the patient's presentation and risk factors 1. Treatment depends on the underlying cause, ranging from simple measures like increased fluid intake and salt consumption for vasovagal syncope to medication adjustments, pacemaker implantation, or specific treatments for structural heart disease, highlighting the need for a precise diagnosis to guide effective management 1.
From the Research
Work-up for Syncope
The work-up for syncope involves a thorough clinical assessment to identify the underlying cause and quantify the risk to the patient 2. The goals of the clinical assessment are:
- To identify the precise cause of syncope in order to implement a mechanism-specific and effective therapeutic strategy
- To quantify the risk to the patient, which depends on the underlying disease rather than the mechanism of syncope
Classification of Syncope
Syncope can be classified into three main categories:
- Cardiac syncope: due to structural or electrical cardiovascular causes
- Reflex syncope (neurally mediated): includes vasovagal syncope, situational syncope, carotid sinus syncope, and atypical reflex syncope
- Orthostatic syncope: caused by an abnormal drop in systolic blood pressure upon standing
Diagnostic Evaluation
The diagnostic evaluation of syncope includes:
- History-taking: the most important aspect of the clinical assessment 2, 3, 4
- Physical examination: including orthostatic blood pressure measurements 2, 5, 6
- Electrocardiogram (ECG): a mandatory diagnostic tool to identify patients with high likelihood of cardiac syncope due to arrhythmic or cardiopulmonary disorder 3, 5, 4
- Additional testing: may be considered if the findings are inconclusive and indicate possible adverse outcomes, such as prolonged electrocardiographic monitoring, stress testing, and echocardiography 5, 6, 4
Risk Stratification
Risk stratification is important to determine the need for hospital admission and to inform decisions regarding management. Risk stratification tools, such as the Canadian Syncope Risk Score, may be beneficial in this decision 5. Patients with cardiac syncope are at higher risk of adverse outcomes, while those with reflex and orthostatic syncope have a good prognosis 5.
Management
The management of syncope depends on the underlying cause and includes:
- Addressing any exacerbating medication and providing general measures to increase blood pressure, such as physical counter-pressure manoeuvres, in patients with reflex or orthostatic syncope 2
- Referral to a cardiologist for appropriate management in patients with cardiac syncope 2
- Monitoring and further evaluation in patients with suspected cardiac syncope or high-risk patients 3, 6