Syncope

Differential Diagnosis

• Neurally mediated (45% of cases): Increased parasympathetic/vagal tone → bradycardia and hypotension

  • Vasovagal: Syncope occurred in a warm/crowded space after prolonged standing and was associated with emotion/fear/pain. Patient reports associated nausea and bystanders noted transient diaphoresis.

  • Situational: New onset syncope occurred during episode of coughing while voiding after a meal

  • Consider seizure (eyes open) and psychogenic syncope (eyes closed with rapid, complete recovery)

• Cardiac (20% of cases): Generally considered a high risk patient (see below)

  • Arrhythmia (most common): Elderly patient with personal h/o atrial fibrillation/flutter and family h/o sudden, unexplained death presents with new onset palpitations during exercise and abnormal EKG. Treatment per arrhythmia.

  • Structural cardiac abnormality/cardiomyopathy: Elderly patient with h/o valvular and infiltrative (sarcoidosis, hemochromatosis, amyloidosis) heart disease presents chest pain at rest, syncope during exercise. Evidence of heart failure on physical exam and PR interval > 200 ms (heart block) on EKG.

  • Hypertrophic cardiomyopathy: Pediatric patient with family h/o sudden cardiac death presents with new onset syncope that occured while exercising in hot weather. Start nadolol; transition to verapamil if ineffective.

• Orthostatic hypotension (10% of cases): Decrease of ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes of moving from supine to upright position

  • Patient with h/o autonomic dysfunction due to alcoholism, DM, Parkinson disease, multiple sclerosis presents with syncope during postural change. Recent, acute volume loss due to dehydration, hemorrhage. Consumes low-salt diet.

  • Recent changes in medications: Alpha blockers (tamsulosin), beta-blockers (metoprolol), calcium channel blockers (amlodipine), diuretics (furosemide), phosphodiesterase inhibitors (e.g. sildenafil), SSRIs

  • Tachycardia and positive orthostatic vital signs on exam

Evaluation and Treatment

Obtain history with focus on precipitating events, h/o cardiac disease, and clinical features above

• Obtain orthostatic vital signs

• Obtain CBC, CMP; consider BNP if evidence of heart failure

• Evaluate EKG for prolonged PR interval, arrhythmia

• Specific etiologies

  • Neurogenic syncope

    • Vasovagal/situational hypotension: IV hydration, patient education. Consider tilt table test to confirm bradycardia/hypotension with change in position.

    • Event not explained by vasovagal or situational syncope: Consider EMG, psychiatry consult

  • Unexplained and/or suspected cardiac syncope

    • High risk: Telemetry, echocardiogram. Consider Holter monitor/loop recorder, cardiac stress test.

    • Low risk or negative hospital workup: Consider Holter monitor/loop recorder to detect arrhythmia

  • Orthostatic hypotension: Modify risk factors; if refractory, consider starting midodrine, fludrocortisone, or droxidopa

• Risk stratification

  • Admit to hospital if patient is high risk due to any of the following: Age > 50 years, syncope with exertion, personal h/o heart disease, familial h/o sudden death, systolic < 90 mmHg, arrhythmia on EKG

  • Risk of adverse event within 30 days calculated per Canadian Syncope Risk Score