What is the recommended workup for a patient presenting with fainting (syncope), considering their age, sex, past medical history, and potential underlying conditions such as orthostatic hypotension or cardiac arrhythmias?

Workup for Fainting (Syncope)

All patients presenting with syncope require an initial evaluation consisting of detailed history, physical examination with orthostatic blood pressure measurements, and a 12-lead ECG—this triad establishes the diagnosis in 23-50% of cases and guides all subsequent testing. 1

Initial Evaluation Components

History Taking Priorities

Document the exact circumstances and characteristics of the event:

• Position when syncope occurred (supine, sitting, or standing) and activity at onset (rest, postural change, during/after exercise, urination, defecation, cough, swallowing) 1
• Prodromal symptoms: nausea, vomiting, diaphoresis, warmth, visual changes ("tunnel vision," "graying out"), dizziness, palpitations, chest pain, or neck/shoulder pain 1, 2
• Precipitating factors: crowded/warm places, prolonged standing, post-prandial timing, fear, pain, emotion, neck movements 1
• Duration of loss of consciousness and speed of recovery 1
• Previous episodes and their frequency 2
• Family history of syncope, sudden cardiac death, arrhythmias, channelopathies, or structural heart disease 2
• Medication review, particularly alpha-blockers, antihypertensives, diuretics, sedatives 3, 4

Physical Examination Essentials

Perform orthostatic vital signs correctly:

• Measure blood pressure and heart rate after 5 minutes supine, then at 1 minute and 3 minutes after standing 3, 4
• Orthostatic hypotension is defined as a sustained drop of ≥20 mmHg systolic or ≥10 mmHg diastolic (or ≥30 mmHg systolic if baseline hypertension exists) 1, 3, 4
• Heart rate response matters: increase <15 bpm suggests neurogenic orthostatic hypotension (autonomic dysfunction); increase ≥15 bpm suggests non-neurogenic causes (medications, dehydration, blood loss, cardiac dysfunction) 3, 4

Additional examination components:

• Complete cardiovascular examination including heart sounds, rhythm, murmurs, and peripheral pulses 2
• Carotid sinus massage (supine and upright) in patients >40 years old, as carotid sinus syndrome causes up to 20% of syncope in older adults 1
• Neurological assessment if cognitive impairment or focal deficits suspected 1

Mandatory ECG

Obtain a 12-lead ECG in all patients to detect:

• Conduction abnormalities (AV blocks, bundle branch blocks) 1, 2, 3
• Channelopathies (long QT, short QT, Brugada pattern) 2, 5
• Pre-excitation syndromes 5
• Signs of structural heart disease (Q waves, left ventricular hypertrophy, arrhythmogenic right ventricular dysplasia) 1, 2
• Arrhythmias 3

Risk Stratification for Disposition and Further Testing

High-Risk Features Requiring Hospitalization and Urgent Evaluation

Admit patients with any of the following:

• Abnormal ECG (any of the findings above) 1
• Known structural heart disease or heart failure 1, 6
• Syncope during exertion or while supine 1, 5
• Chest pain or palpitations preceding syncope 2
• Family history of sudden cardiac death 1
• Absence of prodromal symptoms (suggests arrhythmic cause) 2
• Age >65 years with unexplained syncope 1
• Shortness of breath 1
• Systolic blood pressure <90 mmHg 1
• Hematocrit <30% 1

Low-Risk Features (Outpatient Management Appropriate)

Patients can be safely discharged when:

• Clear vasovagal trigger present (emotional stress, pain, prolonged standing, warm environment) 2
• Typical prodromal symptoms (nausea, warmth, diaphoresis, visual changes) 2
• Normal ECG 1
• No structural heart disease 1, 6
• Post-exercise occurrence (not during exercise) 2
• Young age without concerning features 1

Subsequent Testing Based on Initial Evaluation

When Cardiac Cause Suspected (High-Risk Features Present)

Proceed with:

• Echocardiogram to evaluate for structural heart disease, valvular abnormalities, or cardiomyopathy 1
• Immediate cardiac monitoring (telemetry or Holter) if arrhythmic syncope suspected 1
• Cardiology referral for consideration of electrophysiologic study if structural heart disease present 6
• Ambulatory cardiac monitoring (extended Holter, event recorder, or implantable loop recorder) for recurrent unexplained syncope 6

When Orthostatic Hypotension Confirmed

Management approach:

• Review and discontinue medications worsening orthostatic hypotension (alpha-blockers, centrally acting antihypertensives, calcium channel blockers, sedatives) 3, 4
• Lifestyle modifications: increase fluid intake to 2-3 liters daily, increase salt intake, sleep with head of bed elevated 10 degrees 3, 4
• Physical counterpressure maneuvers: teach leg crossing, squatting, arm tensing, bending forward at waist 3, 4
• Pharmacologic therapy: midodrine is first-line for symptomatic orthostatic hypotension persisting despite nonpharmacologic measures 4

When Reflex (Neurally-Mediated) Syncope Suspected

Confirm diagnosis with:

• Head-up tilt testing when syncope is position-related or reflex mechanism suspected, particularly in patients without structural heart disease 1, 6
• Tilt testing with nitroglycerine provocation may be needed in some cases 7

Laboratory Testing

Order only when clinically indicated based on history and examination:

• Complete blood count if anemia suspected 1
• Electrolytes if dehydration or metabolic abnormality suspected 2
• Routine laboratory testing is not recommended for all syncope patients 2, 3

Special Population Considerations

Older Adults (>65 Years)

The most common causes are orthostatic hypotension (20-30%), carotid sinus syndrome (up to 20%), and cardiac arrhythmias 1, 8

• Always perform carotid sinus massage (supine and upright) as diagnostic response only present upright in one-third of cases 1
• Consider unexplained falls as syncope equivalent, especially with retrograde amnesia 1, 8
• Orthostatic hypotension assessment is critical as prevalence ranges from 6% in community-dwelling elderly to 33% in hospitalized elderly 1
• Delayed orthostatic hypotension (>3 minutes after standing) is common due to stiffer hearts and impaired compensatory reflexes 4

Adolescents

Vasovagal syncope is the most common cause, but cardiac causes must be excluded 2

• Focus on identifying high-risk features (syncope during exercise, abnormal ECG, family history of sudden death, absence of prodrome, chest pain/palpitations) 2
• Low-risk features (clear vasovagal trigger, typical prodrome, post-exercise timing) indicate benign etiology 2

Common Pitfalls to Avoid

• Do not assume supine syncope is always benign—while rare, neurogenic syncope can occur in the supine position ("sleep fainting") and requires thorough cardiac and neurological evaluation to exclude other causes 5
• Do not rely solely on patient history in older adults—cognitive impairment and retrograde amnesia are common, making collateral history essential 1, 8, 9
• Do not measure orthostatic vitals incorrectly—must wait full 5 minutes supine and measure at both 1 and 3 minutes standing, as delayed orthostatic hypotension may not manifest immediately 3, 4
• Do not overlook medication review—polypharmacy is a leading reversible cause of orthostatic hypotension 3, 4
• Do not order extensive neurological testing routinely—indicated only when history suggests non-syncopal loss of consciousness (seizure, stroke) 1