Syncope – Dr. Islam Abusido, MD, FACC (EP HF Taskforce)
Syncope – Dr. Islam Abusido, MD, FACC (EP HF Taskforce )”
1. Definition & Overview
• Syncope: transient loss of consciousness and postural tone, followed by spontaneous recovery.
• Often preceded by dizziness, nausea, diaphoresis, visual changes.
• Accounts for 1–3.5 % of ER visits and 6 % of hospital admissions.
• Can range from benign to life-threatening causes.
2. Epidemiology
• Cardiac causes → more common in older adults.
• Vasovagal (non-cardiac) → frequent in young people.
• Gender: no significant difference between men and women.
3. Main Causes:
1. Cardiovascular:
• Arrhythmias (tachy- or brady-).
• Structural: valvular disease, MI, HCM, pulmonary embolism:
- PE (Pulmonary Embolism): (Syncope with sudden dyspnea, chest pain, hypoxia — due to acute right heart strain.)
- MI (Myocardial Infarction): (Syncope from severe ischemia or arrhythmia during or after a chest pain episode.)
- Valvular Disease (esp. Aortic Stenosis): (Syncope on exertion, due to fixed cardiac output obstruction.)
- HCM (Hypertrophic Cardiomyopathy): (Syncope with exertion or sudden standing, from LVOT obstruction or arrhythmia.)
2. Cerebrovascular:
• Vertebrobasilar insufficiency.
3. Vascular Tone / Blood Flow Disorders:
• Vasovagal (neurocardiogenic) syncope.
• Orthostatic hypotension.
• Carotid-sinus syncope.
• Situational syncope (micturition, coughing, swallowing, postprandial).
4. Mimics:
• Seizures.
• Hypoglycemia.
• Hypoxia.
• Psychogenic disorders.
4. Pathophysiology
• Brain requires constant glucose and oxygen; interruption for seconds → LOC.
• Maintained by cardiac output + vascular resistance + MAP + volume.
• “Near-syncope” = feeling of imminent faint; shares same mechanism (hypoperfusion).
• Episodes > a few minutes = not syncope, likely neurologic (e.g., seizure).
5. Clinical Evaluation
• History + physical identify cause in ~50 % of cases.
• Focus: duration, triggers, prodrome, posture, medications.
• Standing → vasovagal; supine or no warning → cardiac origin.
• Examine vitals, cardiac & neuro findings.
Vertebrobasilar Insufficiency (VBI) – Brief Evaluation:
• Suspect VBI when dizziness or vertigo occurs with other brainstem symptoms such as diplopia, ataxia, dysarthria, dysphagia, or drop attacks — not with isolated vertigo alone.
📌 Isolated dizziness rarely indicates vertebrobasilar insufficiency.
• Check both arm BPs to exclude subclavian steal syndrome.
6. Diagnostic Work-up
• Baseline: ECG + blood glucose (mandatory).
• Labs: CBC, electrolytes, cardiac enzymes as indicated.
• Echocardiography: if heart disease suspected.
• Continuous/event monitoring for arrhythmias.
• Neuro-imaging if cerebrovascular:
• Best test: MRI/MRA of brain and neck → evaluates vertebral & basilar arteries and detects posterior circulation ischemia.
• Alternative: CT angiography (CTA) if MRI not possible.
• Carotid Doppler not useful — does not assess posterior circulation.
• EEG if seizures possible.
• Exercise test: to reveal ischemia, HOCM, or channelopathies.
• Tilt-table test:
• For recurrent unexplained syncope or to confirm vasovagal cause.
• Contraindicated in IHD, severe HTN, AS, or LVOT obstruction.
• Electrophysiology study (EPS):
• For high-risk or recurrent unexplained syncope, esp. with structural heart disease, BBB, Brugada, ARVC.
7. Management
• General: treat underlying cause; keep patient supine with legs elevated during event.
• Vasovagal syncope:
• Avoid triggers, increase fluids & salt, tilt training.
• Medications: β-blockers, SSRIs, fludrocortisone, midodrine.
• DDD pacemaker reduces recurrent falls.
• Orthostatic hypotension:
• Rise slowly; avoid diuretics/vasodilators; use compression stockings; give IV fluids if depleted; midodrine for refractory cases.
• Cardiac syncope:
• Manage per etiology—antiarrhythmics, pacing, ablation, ICD if indicated.
8. Risk Stratification
• Boston Syncope Criteria:
• Admission if cardiac disease, chest pain, dyspnea, palpitations, or abnormal ECG.
• Low-risk patients (no heart disease, age < 50, normal ECG) → safe for outpatient follow-up.
• High-risk factors: arrhythmic features, hypotension, CHF, CAD, family history of sudden death.
• Low-risk: young, normal ECG, typical vasovagal or orthostatic pattern.
9. Differential Diagnosis
• Seizures: aura, tonic-clonic movements, incontinence, postictal confusion.
• Hypoglycemia: sweating, tremor, irritability.
• Panic attacks: impending doom, palpitations, air hunger, perioral tingling.
• Distinguishing these is crucial for accurate management.
10. Key Takeaways / Pearls
• Most cases are benign vasovagal.
• Cardiac syncope can be fatal → must exclude.
• ECG diagnostic yield ≈ 5 %, but still essential.
• History + exam remain most valuable tools.
• Advise patients not to drive until evaluation complete.
• Consider mental health / substance abuse if etiology unclear.
11. Case Highlights
• Young athlete fainting during exertion: rule out HOCM with echocardiogram before returning to sports.
• Older woman with normal tests: external event monitor (1–2 weeks) is best next step.
• Carotid disease or emboli do not cause syncope.
