What is the differential diagnosis and workup for syncope (fainting)?

From the Guidelines

Syncope differential diagnosis requires a systematic approach focusing on cardiac, neurologic, and orthostatic causes, with the most recent guidelines from 2021 emphasizing the importance of a thorough history and physical examination, as well as selective use of additional testing 1.

Key Considerations

• The initial evaluation should include a careful history, physical examination, and standard electrocardiogram (ECG) to differentiate true syncope from non-syncopal conditions 1.
• Cardiac causes of syncope include arrhythmias, structural heart disease, and cardiac ischemia, while neurologic causes include vasovagal syncope, situational syncope, and carotid sinus hypersensitivity 1.
• Orthostatic hypotension may result from volume depletion, medications, or autonomic dysfunction, and initial workup should include orthostatic vital signs, 12-lead ECG, and basic laboratory tests (CBC, electrolytes, glucose, renal function) 1.

Diagnostic Approach

• A thorough history and physical examination are crucial in determining the cause of syncope, with particular attention to circumstances surrounding the event, prodromal symptoms, and witness accounts 1.
• Additional testing, such as echocardiogram, Holter or event monitoring, tilt-table testing, and carotid sinus massage, should be guided by clinical suspicion and used selectively to avoid unnecessary costs and hospitalization 1.
• Brain imaging is rarely indicated unless focal neurologic findings are present, and hospitalization should be considered for patients with cardiac disease, abnormal ECG, older age, or recurrent episodes 1.

Prioritization of Testing

• The 2021 guidelines from the American College of Radiology emphasize the importance of selective use of imaging tests, such as head CT and MRI, and recommend against routine use in patients with syncope or presyncope without other indications 1.
• The guidelines also recommend a resting 12-lead electrocardiogram (ECG) for all patients to detect arrhythmias or abnormality indicative of higher risk for arrhythmia 1.

Conclusion is not allowed, so the response is ended here.

From the Research

Syncope Differential Diagnosis

• Syncope is classified into three main types: neurally mediated, cardiac, and orthostatic hypotension 2, 3
• Neurally mediated syncope is the most common type and has a benign course, whereas cardiac syncope is associated with increased morbidity and mortality 2
• The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic 3

Workup and Evaluation

• The initial assessment for all patients presenting with syncope includes a detailed history, physical examination, and electrocardiography 2, 3
• Laboratory testing and neuroimaging have a low diagnostic yield and should be ordered only if clinically indicated 2, 3
• Electrocardiographic (ECG) monitoring is a well-established procedure in the work-up of patients with syncope or for diagnosing arrhythmias 4, 5
• A standardized approach to syncope evaluation reduces hospital admissions and medical costs, and increases diagnostic accuracy 2

Risk Stratification and Management

• Patients with presyncope have similar prognoses to those with syncope and should undergo a similar evaluation 2
• Low-risk patients with a single episode of syncope can often be reassured with no further investigation 2
• High-risk patients with cardiovascular or structural heart disease, history concerning for arrhythmia, abnormal electrocardiographic findings, or severe comorbidities should be admitted to the hospital for further evaluation 2, 3
• The treatment of neurally mediated and orthostatic hypotension syncope is largely supportive, although severe cases may require pharmacotherapy 2
• Cardiac syncope may require cardiac device placement or ablation 2