PRESYNCOPE

Sensation of impending LOC without actual LOC — same etiologies as syncope; requires equivalent risk stratification

SYMPTOMS / ASSOCIATED SX

  • Lightheadedness, dizziness, "graying out," blurred vision, weakness, diaphoresis without actual LOC

  • Positional component (orthostatic), post-prandial, exertional, or situational triggers

  • Palpitations accompanying symptoms (cardiac etiology)

  • Exam: orthostatic VS, cardiac auscultation, skin turgor, mucous membranes

DENIES

  • Actual LOC (distinguishes from syncope)

  • Focal neurologic deficits (TIA/stroke)

  • Exertional component with chest pain (ACS, HCM, AS)

  • Dyspnea at rest (PE, acute decompensated HF)

SOCIAL HISTORY

  • Recent vomiting, diarrhea, fever, poor PO intake (volume depletion); alcohol; heat exposure

  • Occupation: prolonged standing; high-risk if syncopal event occurs (driver, pilot)

MAIN ETIOLOGY

  • Orthostatic hypotension: most common in hospitalized patients — volume depletion, medications, autonomic dysfunction

  • Vasovagal: same triggers as syncope

  • Cardiac arrhythmia: less common but must exclude

  • Anemia (reduced O2 delivery), hypoglycemia, medication effect (alpha-blockers, nitrates, antihypertensives)

MOST COMMON DDX

  • True syncope (brief LOC occurred but patient unaware — witness history crucial)

  • Dizziness/vertigo (vestibular — spinning quality, nystagmus, positive Dix-Hallpike)

  • Hypoglycemia (fingerstick <70)

  • Anemia (CBC — Hgb <8 with exertional symptoms)

  • Anxiety/panic attack (hyperventilation, perioral tingling, no hemodynamic change)

  • TIA (focal deficit, neuroimaging)

DATA

  • Orthostatic VS ×3 (key diagnostic test)

  • ECG; fingerstick glucose; BMP; CBC

  • Troponin if chest pain or exertional symptoms

  • Continuous telemetry if cardiac features

  • Echo if murmur or structural disease suspected; TSH

HOME MEDS

  • Antihypertensives/diuretics — hold if orthostatic

  • Alpha-blockers (tamsulosin, doxazosin) — hold; common overlooked culprit especially post-meal

  • Nitrates — hold; insulin/sulfonylureas — hold if hypoglycemia suspected

PLAN

  • Risk-stratify same as syncope — apply SFSR/ROSE; admit if high-risk features

  • IV fluids if volume depleted: NS 500 mL–1 L IV bolus; reassess orthostatic VS; transition to PO once tolerating

  • Correct underlying cause: anemia (transfuse if Hgb <7–8 symptomatic), electrolytes, glucose

  • Orthostatic hypotension:

    • Deprescribe culprit medications

    • Salt/fluid loading; compression stockings; rise slowly

    • Midodrine 2.5–10 mg PO TID or fludrocortisone 0.1 mg daily if refractory

  • Telemetry if any cardiac features; PT/OT if recurrent in elderly

  • DISCHARGE:

    • Medication reconciliation — document held/discontinued agents

    • PCP follow-up within 1 week; cardiology if cardiac etiology

    • Outpatient event monitor if recurrent and unexplained

RED FLAGS

  • Exertional presyncope — treat as exertional syncope; urgent cardiac workup

  • Palpitations preceding symptoms — telemetry, cardiology consult

  • ECG abnormalities (Brugada, delta wave, QTc >500ms, AV block)

  • Presyncope while supine

  • Age >60 with multiple episodes without clear benign etiology

SENIOR IM RESIDENT PEARLS

  • Presyncope carries the same mortality risk as syncope in prospective studies — do not under-triage

  • Post-prandial hypotension: SBP drop ≥20 within 2h of eating — common in elderly/Parkinson's; acarbose 25–50 mg TID with meals

  • Alpha-1 blockers (tamsulosin) frequently missed — always ask specifically about BPH medications

  • Common mistake: attributing all orthostatic symptoms to dehydration without medication review

  • Hyperventilation test: 30 seconds of voluntary hyperventilation reproducing symptoms → anxiety/panic

  • Compression stockings: ensure proper fitting (20–30 mmHg) and education on donning before standing