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cardio.neurally-mediated-reflex-syncope.v1

Neurally-Mediated Reflex Syncope (vasovagal / situational / carotid sinus)

cardiologyacutechronicadult
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12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Confirm syncope — transient LOC due to global cerebral hypoperfusion with rapid recovery, no postictal (ESC 2018 Brignole — definition) vs seizure / metabolic / pre-syncope

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Syncope confirmed and broad differential narrowed

Patient inputs (19)

Risk stratification + pacing eligibility (BIOSync >40) (ACC/AHA 2022)

Orthostatic vitals + supine vs standing pattern (ACC/AHA/HRS 2017)

Bradycardia at event, baseline HR pattern (ESC 2018 Brignole)

Classic vasovagal pattern vs cardiac arrhythmic syncope — no prodrome, exertional, supine (ESC 2018 Table 4)

Inherited arrhythmia syndromes — long QT, Brugada, HCM, ARVC (ACC/AHA/HRS 2017 high-risk features)

Reduces probability of benign reflex etiology; raises Canadian Syncope Rule risk (Thiruganasambandamoorthy JAMA 2016)

Antihypertensives, diuretics, alpha-blockers, vasodilators, QT-prolonging agents (ACC/AHA/HRS 2017)

Drop ≥20 SBP / ≥10 DBP / new symptoms within 3 min standing — orthostatic vs reflex pattern (ACC/AHA/HRS 2017; ESC 2018)

Mandatory for any syncope — long QT, Brugada, WPW, AV block, ischemic changes, HCM patterns (ESC 2018 Class I; ACC/AHA/HRS 2017 Class I)

When structural heart disease suspected by history / exam / ECG (ACC/AHA/HRS 2017 Class IIa)

Tilt-table reproduces vasovagal in equivocal cases — not routine (ESC 2018 Class IIb)

Diagnose carotid sinus syndrome — pause >3 s OR SBP drop >50 mmHg (ESC 2018 Brignole)

Recurrent unexplained syncope after initial workup (ESC 2018 Class I for recurrent unexplained)

Suggests absent prodrome — cardiac etiology more likely (ESC 2018 Brignole)

Anemia / GI bleed mimic (ACC/AHA/HRS 2017 — selective labs)

Volume / electrolyte status; QT-affecting K+ / Mg (ACC/AHA/HRS 2017)

Hypoglycemia mimic (ACC/AHA/HRS 2017)

Exclude ACS / myocardial injury; selective use (ACC/AHA/HRS 2017)

HF mimic (ACC/AHA/HRS 2017 — selective)

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Severity triggers (7)

7 need judgement
  • informationalseveresyncope_with_high_risk_ecg (ACC/AHA 2022)
    New long QT, Brugada pattern, WPW, AV block, BBB with axis change, ischemic changes, or ARVC pattern (ESC 2018 Table 5 high-risk ECG features)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereexertional_or_supine_syncope
    Syncope occurred during exertion or while supine (ESC 2018 — red flag for cardiac syncope)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverefamily_history_sudden_cardiac_death
    First-degree relative <40 with sudden cardiac death or known channelopathy / cardiomyopathy (ACC/AHA/HRS 2017 high-risk feature)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverecardioinhibitory_subtype_pacing_eligible
    Recurrent syncope ≥2/yr, age >40, asystole ≥3 s on tilt or ILR (cardioinhibitory) (ACC/AHA 2022)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveresyncope_with_injury_or_no_prodrome
    Syncope with injury or absent prodrome — raises cardiac etiology (ESC 2018 Brignole — high-risk feature)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatesupine_htn_on_midodrine
    Supine SBP ≥160 with daytime midodrine therapy (POST IV — known AE) (ACC/AHA 2022)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatefludrocortisone_hypokalemia_or_edema
    K+ <3.5 mmol/L or new peripheral / pulmonary edema on fludrocortisone (POST II NEJM 2013 — known AE)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Reflex syncope stepwise therapy (lifestyle → pharmacotherapy → device for cardioinhibitory subtype) (ACC/AHA 2022)
axis: reflex_syncope_stepwisestep 1 - Step 1 — Education + trigger avoidance + counterpressure maneuvers (foundation for all)
Selected step "Step 1 — Education + trigger avoidance + counterpressure maneuvers (foundation for all)" — All reflex syncope patients regardless of severity
  • oral_rehydration_salt_loading
    first line
    lifestyle
    2–3 L water + 6–10 g sodium daily (if not contraindicated) • PO • daily
    ESC 2018 Class I / ACC/AHA/HRS 2017 Class I — first-line for all reflex syncope; expands intravascular volume

outpatient playbook — drug actions (5)

  1. 1. lifestyle + counterpressure maneuvers (ACC/AHA 2022)
    2–3 L water + 6–10 g salt daily • PO • daily
    trigger: All reflex syncope (ACC/AHA 2022)
    Foundation (ESC 2018 Class I; ACC/AHA/HRS 2017 Class I)
  2. 2. midodrine
    5–10 mg PO TID • PO • TID (last dose ≥4 h before bed)
    trigger: Recurrent despite lifestyle (ACC/AHA 2022)
    Vasoconstriction (POST IV; ESC 2018 Class IIb)
  3. 3. fludrocortisone
    0.1–0.2 mg PO daily • PO • daily
    trigger: Volume-depleted / hypotensive subtype or POST II positive (ACC/AHA 2022)
    Volume expansion (POST II NEJM 2013)
  4. 4. pacemaker referral
    NA • EP referral • as indicated
    trigger: Cardioinhibitory ≥3 s asystole + age >40 + ≥2 episodes/yr (ACC/AHA 2022)
    BIOSync NEJM 2021 — Class IIa ESC 2018 update
  5. 5. paroxetine or atomoxetine
    Paroxetine 20 mg daily; atomoxetine 40 mg daily • PO • daily
    trigger: Refractory after Steps 1–3 (ACC/AHA 2022)
    Second-line evidence (ESC 2018 Class IIb)

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Transient loss of consciousness with rapid spontaneous recovery (ESC 2018 Brignole — definition of syncope); Prodrome of warmth, nausea, diaphoresis, blurred vision, lightheadedness (ESC 2018 — classic vasovagal prodrome); Trigger — emotional stress, prolonged standing, micturition, defecation, cough, swallowing (ACC/AHA/HRS 2017 — situational subtypes).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Neurally-Mediated Reflex Syncope (vasovagal / situational / carotid sinus)** (cardio.neurally-mediated-reflex-syncope.v1).
Phenotype framing: Reflex (vasovagal / situational / carotid sinus) vs orthostatic vs cardiac arrhythmic vs structural cardiac vs neurologic — per ESC 2018 classification
Scope: Confirm syncope — transient LOC due to global cerebral hypoperfusion with rapid recovery, no postictal (ESC 2018 Brignole — definition) vs seizure / metabolic / pre-syncope

No severity triggers fired against current inputs.

Plan

Regimen axis: **Reflex syncope stepwise therapy (lifestyle → pharmacotherapy → device for cardioinhibitory subtype) (ACC/AHA 2022)** — step "Step 1 — Education + trigger avoidance + counterpressure maneuvers (foundation for all)".
1. oral_rehydration_salt_loading 2–3 L water + 6–10 g sodium daily (if not contraindicated) PO daily (lifestyle, first line) — ESC 2018 Class I / ACC/AHA/HRS 2017 Class I — first-line for all reflex syncope; expands intravascular volume

Setting playbook (outpatient) — Stepwise reflex syncope therapy with serial recurrence assessment, safety guidance, and pacing decision when criteria met (ACC/AHA 2022)
2. lifestyle + counterpressure maneuvers (ACC/AHA 2022) 2–3 L water + 6–10 g salt daily PO daily — All reflex syncope (ACC/AHA 2022) (Foundation (ESC 2018 Class I; ACC/AHA/HRS 2017 Class I))
3. midodrine 5–10 mg PO TID PO TID (last dose ≥4 h before bed) — Recurrent despite lifestyle (ACC/AHA 2022) (Vasoconstriction (POST IV; ESC 2018 Class IIb))
4. fludrocortisone 0.1–0.2 mg PO daily PO daily — Volume-depleted / hypotensive subtype or POST II positive (ACC/AHA 2022) (Volume expansion (POST II NEJM 2013))
5. pacemaker referral NA EP referral as indicated — Cardioinhibitory ≥3 s asystole + age >40 + ≥2 episodes/yr (ACC/AHA 2022) (BIOSync NEJM 2021 — Class IIa ESC 2018 update)
6. paroxetine or atomoxetine Paroxetine 20 mg daily; atomoxetine 40 mg daily PO daily — Refractory after Steps 1–3 (ACC/AHA 2022) (Second-line evidence (ESC 2018 Class IIb))

Non-pharmacologic actions:
- Education on prodromal recognition + counterpressure maneuvers — leg crossing + hand grip + arm tensing (ESC 2018 Class I)
- Trigger avoidance — prolonged standing, heat, dehydration, alcohol (ESC 2018; ACC/AHA/HRS 2017)
- Sleep with head-of-bed elevation 10° to reduce supine HTN risk while on midodrine / fludrocortisone (ESC 2018)
- Driving + occupational restriction counselling (ESC 2018 §6.4)
- Tilt-training — some evidence for daily 30-min standing exercise (Ector Pacing Clin Electrophysiol 1998; ESC 2018 Class IIb)

AVOID / contraindication checks:
- Midodrine_avoid_severe_HTN_or_supine_HTN (POST IV) (ACC/AHA 2022)
- Midodrine_avoid_within_4h_of_bed (POST IV — supine HTN risk) (ACC/AHA 2022)
- Fludrocortisone_monitor_K_BP (POST II NEJM 2013)
- Paroxetine_serotonin_syndrome_combo (ESC 2018)
- Beta_blocker_not_first_line_in_vasovagal (ESC 2018 — POST V negative; ACC/AHA/HRS 2017 Class III)

Monitoring

Regimen monitoring:
- Symptom diary and BP log (ESC 2018)
- Recurrence frequency q 3 6 months (ESC 2018)
- Supine HTN check with midodrine (POST IV) (ACC/AHA 2022)
- K and BP with fludrocortisone q 4 8 weeks (POST II NEJM 2013)
- Pacemaker interrogation q 6 12 months if implanted (BIOSync NEJM 2021)
- Tilt table re test only if protocol change (ESC 2018)

Setting (outpatient) monitoring:
- Recurrence frequency at 6 + 12 weeks then q 3–6 months (ACC/AHA 2022)
- BP supine + standing q visit (ACC/AHA 2022)
- K+ q 4–8 weeks initially with fludrocortisone (ACC/AHA 2022)
- Pacemaker interrogation if implanted (ACC/AHA 2022)

Follow-up plan: Driving restrictions per local rules (ESC 2018 §6.4); occupational counselling; reassessment of BP-lowering meds; safety planning for warning signs + counterpressure maneuvers (ACC/AHA/HRS 2017)
- Close-out criterion: Follow-up plan + safety + driving / occupational guidance documented

Monitoring phase: Outpatient: symptom diary, BP log, recurrence frequency, fluid + salt adherence (ESC 2018); pacemaker interrogation if implanted; tilt-table for protocol assessment

Disposition

Current setting: outpatient — Stepwise reflex syncope therapy with serial recurrence assessment, safety guidance, and pacing decision when criteria met (ACC/AHA 2022)

Disposition criteria:
- Continue current step if recurrence reduced (ACC/AHA 2022)
- Step up if persistent recurrence (ACC/AHA 2022)
- Pacemaker referral when BIOSync criteria met (ACC/AHA 2022)

Escalation triggers (move to higher acuity):
- New high-risk symptoms (palpitations, exertional, supine, injury) → cardiology + cardiac workup (ACC/AHA 2022)
- Persistent disabling recurrence despite Step 3 → autonomic specialist + ILR + tilt re-evaluation

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [SEVERE] New long QT, Brugada pattern, WPW, AV block, BBB with axis change, ischemic changes, or ARVC pattern (ESC 2018 Table 5 high-risk ECG features)
- [SEVERE] Syncope occurred during exertion or while supine (ESC 2018 — red flag for cardiac syncope)
- [SEVERE] First-degree relative <40 with sudden cardiac death or known channelopathy / cardiomyopathy (ACC/AHA/HRS 2017 high-risk feature)

Citations

- 2017 ACC/AHA/HRS Syncope Guideline + 2018 ESC Syncope Guideline (BIOSync 2020 update) [PMID:28280232](https://pubmed.ncbi.nlm.nih.gov/28280232/)
- Cited evidence (PMID 29562304) [PMID:29562304](https://pubmed.ncbi.nlm.nih.gov/29562304/)
- Cited evidence (PMID 27179518) [PMID:27179518](https://pubmed.ncbi.nlm.nih.gov/27179518/)
- Cited evidence (PMID 23381622) [PMID:23381622](https://pubmed.ncbi.nlm.nih.gov/23381622/)
- Cited evidence (PMID 32115827) [PMID:32115827](https://pubmed.ncbi.nlm.nih.gov/32115827/)

Last reconciled with current guidelines: 2026-04-27.
References