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cardio.post-arrest.long-qt-channelopathy.v1PRODUCTION
cardio.post-arrest.long-qt-channelopathy.v1

Post-cardiac-arrest care — congenital long-QT channelopathy (KCNQ1 / KCNH2 / SCN5A) with TdP-arrest

cardiologyacuteadultpediatric
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12/12 authored

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

Current phase

Frame

Detailed

Recognize post-ROSC + QTc > 500 ms + structurally normal heart + classic trigger pattern as congenital LQT-arrest cohort; pivot from generic post-arrest care to channelopathy-specific avoidance protocol; route to parent cardio.post-arrest.core.v1 for TTM + neuroprog while specializing on QTc reassessment + family screening + drug-avoidance + lifelong β-blocker + ICD

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congenital LQT high pretest probability confirmed + structural disease screen initiated

Patient inputs (24)

Congenital LQT typically manifests in childhood / adolescence / young adulthood; pediatric resuscitation modifications below age 8; ICD device-size considerations in pediatric / small-frame patients

LQT2 has female predominance for events (especially post-partum); informs counseling + risk stratification + cascade-testing prioritization

Trigger pattern is highly informative: LQT1 = exertion/swimming; LQT2 = auditory/emotional/post-partum; LQT3 = sleep/nocturnal; predicts subtype before genetic results return

CPR within 1 min dramatically improves outcome; CAHP/OHCA score input

AED within 3 min → 50%+ survival; venue AED program presence is dominant prognostic factor

VF most common in LQT (~85%); polymorphic VT degenerating to VF is the classic mechanism; informs storm-suppression bridge planning

Family history of SCD <40 y or known LQTS in first-degree relative is a critical input — drives congenital workup priority + cascade screening of relatives

Prior exertional / auditory / nocturnal syncope suggests congenital LQT; recent QT-prolonging drug exposure (macrolide, fluoroquinolone, antipsychotic, methadone, ondansetron, citalopram) suggests acquired or unmasked congenital substrate

Comprehensive medication review against www.crediblemeds.org curated list — STOP all offenders + document; informs whether arrest was triggered by acquired prolongation on a congenital substrate

AKI is major risk for drug-accumulation TdP (sotalol, dofetilide); eGFR for renal-cleared QT-prolonging drug avoidance + dose-adjust

Targeted gene panel — KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3) core panel ≥85% yield; expanded panel for CALM1/2/3, CACNA1C, KCNJ2, ANK2 if family history positive or sentinel features; informs prognosis + cascade testing of relatives

Serial ECGs q4–6 h × 48 h with QTc Bazett + Fridericia; T-wave morphology informs subtype (LQT1 broad-based; LQT2 notched/low-amplitude; LQT3 late-onset narrow); high V1–V2 placement (2nd–3rd ICS) may unmask Brugada overlap; pause-dependence pattern; baseline for ICD planning

Rule out structural disease (HCM, ARVC, anomalous coronary, infiltrative); LQT heart is structurally normal — structural finding triggers alternate or overlap pathway

Often modestly elevated from arrest + CPR; rise pattern helps differentiate from ACS-mediated arrest; LQT-TdP arrest typically negative or modest

Tissue hypoperfusion + post-arrest perfusion debt; clearance trajectory drives prognosis (SCAI 2022 PMID 35718438; CardShock PMID 26333869)

K target ≥4.5 mandatory in LQT — hypokalemia is major TdP precipitant; aggressive replacement

Mg target ≥2.0 mandatory; MgSO4 IV is also FIRST-LINE TdP suppression regardless of measured Mg level (AHA 2020 ACLS)

Hypocalcemia further prolongs QT — replace to normal range

Rib fractures from CPR; pneumothorax; aspiration; baseline for ICD lead placement planning

MAP ≥65 target post-ROSC; SCAI staging if shock; cautious vasopressor dosing in LQT1/2 (adrenergic surge is the trigger)

Bradycardia is a major TdP trigger (LQT3 + acquired); avoid β-blockers acutely if bradycardia-dependent; isoproterenol or pacing pathway may be needed

TTM target 33–37.5 °C × 24 h (TTM2 PMID 34133859); hypothermia paradoxically prolongs QT — re-measure QTc after rewarm before defining baseline

Avoid hyperoxia: SpO2 92–98% (AHA 2020 Class IIa)

Cardiac MRI at 4–6 wk post-arrest if echo equivocal or to rule out CPVT (catecholaminergic polymorphic VT) overlap, ARVC, or infiltrative disease; allows post-arrest stunning to resolve before assessment

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (5)

5 need judgement
  • informationallife_threateningrecurrent_tdp_post_rosc_storm_bridge
    Recurrent TdP / polymorphic VT post-ROSC suggests ongoing storm physiology — MgSO4 2 g IV bolus + 2 g/h infusion regardless of measured Mg level; route to sister cardio.cardiogenic-shock.lqt-tdp-storm.v1 for mid-storm hemodynamic + electrical management; AVOID Class IA + III antiarrhythmics
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningbradycardia_dependent_tdp_recurrence_post_rosc
    Bradycardia-dependent TdP recurrence post-ROSC (LQT3 phenotype or acquired with high-grade AV block / sinus arrest / post-cardioversion pause) — isoproterenol 0.5–2 µg/min OR overdrive transcutaneous / transvenous pacing at 80–100 bpm; AVOID β-blockers acutely (long-term lifesaving in LQT1/2 only)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereinadvertent_qt_prolonging_drug_administered_post_rosc
    Inadvertent administration of QT-prolonging drug post-ROSC (haloperidol, ondansetron > 16 mg, citalopram, macrolide, fluoroquinolone, methadone, Class IA/III antiarrhythmic, antipsychotic) in confirmed or suspected LQT — STOP drug + escalate to EP + chart audit + nursing handoff review; substitute with QT-neutral alternative
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereicd_eligibility_evaluation_lqt_post_arrest
    Sustained VT/VF survivor by definition meets HRS 2017 Class I ICD criteria — implant pre-discharge or schedule within 1 wk; subcutaneous ICD considered if no pacing indication; WCD bridge if ICD deferred for stabilization
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverecascade_family_screening_referral_required
    Confirmed congenital LQT (or strongly suspected pending genetic results) triggers mandatory cascade screening of first-degree relatives — ECG + genetic testing at proband mutation; genetic counseling referral; many newly identified relatives are asymptomatic carriers requiring lifelong management
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Congenital LQT post-arrest phenotype — standard post-ROSC bundle + electrolyte optimization + drug-avoidance protocol + lifelong β-blocker initiation + ICD pathway (HRS 2017 Class I) + cascade family screening
axis: lqt_post_arrest_phenotype
Selected axis "Congenital LQT post-arrest phenotype — standard post-ROSC bundle + electrolyte optimization + drug-avoidance protocol + lifelong β-blocker initiation + ICD pathway (HRS 2017 Class I) + cascade family screening" by default fallback (first axis)
  • magnesium sulfate
    first line
    electrolyte_membrane_stabilizer
    2 g IV bolus over 5–15 min then 2 g/h infusion REGARDLESS of measured Mg level; aggressive replacement to Mg ≥2.0 • IV • continuous; titrate to TdP suppression
    triggers: recurrent_tdp_post_rosc, qtc_above_500_post_rosc, unmasked_lqt_substrate
    AHA 2020 ACLS — FIRST-LINE for TdP regardless of measured Mg level; mechanism stabilizes myocardial membrane independent of measured Mg; HRS 2017 PMID 28219760
    rxcui 6585
  • potassium chloride
    first line
    electrolyte
    20–40 mEq IV/PO until K ≥4.5 mandatory in LQT • IV/PO • PRN until target sustained
    triggers: k_below_4.5_in_lqt_post_arrest, recurrent_tdp_episode
    Hypokalemia is major TdP precipitant; K ≥4.5 target mandatory in LQT; HRS 2017
    rxcui 8591
  • norepinephrine
    first line
    vasopressor_alpha1_beta1
    0.05–0.5 µg/kg/min titrate MAP ≥65; CAUTION in LQT1/2 (adrenergic trigger — minimize dose to lowest effective) • IV • continuous
    triggers: post_rosc_vasoplegia
    SOAP-II PMID 20200382; first-line post-ROSC vasoactive; in LQT1/LQT2 use lowest effective dose because adrenergic surge is the trigger for these subtypes
    rxcui 7512
  • epinephrine
    first line
    inotrope_chronotrope_vasopressor
    1 mg IV q3–5 min during arrest • IV • standard ACLS
    triggers: cardiac_arrest, pea_asystole_during_index_arrest
    AHA 2020 ACLS — standard arrest pathway; in confirmed LQT post-ROSC minimize subsequent infusions because adrenergic load triggers LQT1/2
    rxcui 3992
  • propofol
    first line
    sedative_iv_anesthetic
    5–50 µg/kg/min; titrate RASS • IV • continuous
    triggers: post_rosc_intubation_ttm
    PADIS 2018; preferred sedative in LQT post-arrest because does NOT prolong QT (vs avoiding antipsychotics which do)
    rxcui 8782
  • fentanyl
    first line
    opioid_analgesic
    25–200 µg/h • IV • continuous
    triggers: post_rosc_intubation_ttm, analgesia_ttm
    PADIS 2018; preferred opioid (does NOT prolong QT) over methadone (QT-prolonging — AVOID)
    rxcui 4337
  • dexmedetomidine
    second line
    alpha2_agonist_sedative
    0.2–1.4 µg/kg/h; no bolus • IV • continuous
    triggers: post_rosc_delirium_prevention, avoidance_of_qt_prolonging_antipsychotics
    PADIS 2018; preferred for ICU delirium in LQT cohort because does NOT prolong QT (vs haloperidol — AVOID); Class IIa AHA delirium prevention
    rxcui 48937
  • nadolol
    comorbidity specific
    non_selective_beta_blocker_long_acting
    CONGENITAL LQT1/LQT2 long-term: nadolol 1–1.5 mg/kg/d daily (preferred over propranolol per recent registry data — long half-life + better adherence) • PO • daily; lifelong
    triggers: confirmed_congenital_lqt1_or_lqt2_post_arrest, storm_controlled_initiate_long_term_bb
    HRS 2017 PMID 28219760 Class I + Schwartz International LQTS Registry — mortality reduction in LQT1/2 with long-term β-blocker; nadolol preferred over propranolol (long half-life, daily dosing improves adherence)
    rxcui 7226
  • propranolol
    comorbidity specific
    non_selective_beta_blocker
    CONGENITAL LQT1/LQT2 long-term alternate: propranolol 2–4 mg/kg/d divided BID-QID • PO • BID-QID; lifelong
    triggers: nadolol_unavailable, congenital_lqt1_or_lqt2
    HRS 2017 Class I; Schwartz registry — historical first-line; QID dosing reduces adherence vs nadolol daily
    rxcui 8787
  • mexiletine
    comorbidity specific
    class_ib_sodium_channel_blocker
    CONGENITAL LQT3 long-term: mexiletine 150–300 mg PO q8h • PO • TID
    triggers: confirmed_congenital_lqt3_scn5a_gain_of_function
    HRS 2017 IIa — mexiletine shortens QT in LQT3 by blocking late INa (the gain-of-function defect); does NOT replace ICD
    rxcui 142138
  • isoproterenol
    rescue
    beta1_agonist
    0.5–2 µg/min IV titrate to HR 90–110 for bradycardia-dependent TdP recurrence (LQT3 + acquired); CONTRAINDICATED in LQT1/2 • IV • continuous
    triggers: bradycardia_dependent_tdp_post_rosc, lqt3_phenotype_with_pause_dependent_tdp
    AHA 2020 ACLS — increases HR shortens QT prevents R-on-T; useful for bradycardia-dependent TdP (LQT3 + acquired); CONTRAINDICATED in LQT1/2 (adrenergic trigger)
    rxcui 6054
  • acetaminophen
    first line
    antipyretic_analgesic
    650 mg PO/PR/IV q6h PRN • PO/PR/IV • q6h PRN
    triggers: analgesia_avoid_nsaids_in_aki, fever_post_arrest
    Standard analgesia / antipyresis; does NOT prolong QT
    rxcui 161

outpatient playbook — drug actions (3)

  1. 1. continue β-blocker maintenance for CONGENITAL LQT1/2 lifelong
    rxcui 7226
    nadolol 1–1.5 mg/kg/d (preferred) OR propranolol 2–4 mg/kg/d • PO • daily / BID-QID; lifelong
    trigger: congenital LQT1/LQT2
    HRS 2017 Class I + Schwartz registry mortality reduction
  2. 2. continue mexiletine for CONGENITAL LQT3 lifelong
    rxcui 6750
    150–300 mg PO q8h • PO • TID; lifelong
    trigger: confirmed LQT3
    HRS 2017 IIa — shortens QT by blocking late INa
  3. 3. continue lifelong avoidance of all QT-prolonging drugs (www.crediblemeds.org)
    patient education + curated list • n/a • lifelong
    trigger: LQT diagnosis
    HRS 2017

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: ROSC after out-of-hospital VF arrest with known long-QT syndrome (prior diagnosis, prior syncope, family history) or with sentinel post-ROSC ECG features (QTc > 500 ms, TdP runs); Post-ROSC 12-lead ECG with QTc > 500 ms (Bazett or Fridericia) + structurally normal heart on echo — congenital LQT high concern; pivot from generic post-arrest care to channelopathy-specific avoidance protocol; Witnessed arrest with classic LQT trigger pattern: exertion or swimming (LQT1), auditory startle / emotional / post-partum (LQT2), sleep / nocturnal (LQT3) — directs subtype classification.

Objective

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

Assessment

**Post-cardiac-arrest care — congenital long-QT channelopathy (KCNQ1 / KCNH2 / SCN5A) with TdP-arrest** (cardio.post-arrest.long-qt-channelopathy.v1).
Phenotype framing: Congenital LQT (LQT1 KCNQ1 / LQT2 KCNH2 / LQT3 SCN5A; rarer LQT4-17) vs acquired LQT (drug-induced, electrolyte-driven, AKI-mediated drug accumulation, bradycardia-dependent) vs CPVT overlap (exertion-triggered polymorphic VT with normal QTc) vs Brugada overlap (V1-V3 coved ST) vs idiopathic VF — this differential drives long-term plan + family screening
Scope: Recognize post-ROSC + QTc > 500 ms + structurally normal heart + classic trigger pattern as congenital LQT-arrest cohort; pivot from generic post-arrest care to channelopathy-specific avoidance protocol; route to parent cardio.post-arrest.core.v1 for TTM + neuroprog while specializing on QTc reassessment + family screening + drug-avoidance + lifelong β-blocker + ICD

No severity triggers fired against current inputs.

Plan

Regimen axis: **Congenital LQT post-arrest phenotype — standard post-ROSC bundle + electrolyte optimization + drug-avoidance protocol + lifelong β-blocker initiation + ICD pathway (HRS 2017 Class I) + cascade family screening**.
1. magnesium sulfate 2 g IV bolus over 5–15 min then 2 g/h infusion REGARDLESS of measured Mg level; aggressive replacement to Mg ≥2.0 IV continuous; titrate to TdP suppression (electrolyte_membrane_stabilizer, first line) — AHA 2020 ACLS — FIRST-LINE for TdP regardless of measured Mg level; mechanism stabilizes myocardial membrane independent of measured Mg; HRS 2017 PMID 28219760
2. potassium chloride 20–40 mEq IV/PO until K ≥4.5 mandatory in LQT IV/PO PRN until target sustained (electrolyte, first line) — Hypokalemia is major TdP precipitant; K ≥4.5 target mandatory in LQT; HRS 2017
3. norepinephrine 0.05–0.5 µg/kg/min titrate MAP ≥65; CAUTION in LQT1/2 (adrenergic trigger — minimize dose to lowest effective) IV continuous (vasopressor_alpha1_beta1, first line) — SOAP-II PMID 20200382; first-line post-ROSC vasoactive; in LQT1/LQT2 use lowest effective dose because adrenergic surge is the trigger for these subtypes
4. epinephrine 1 mg IV q3–5 min during arrest IV standard ACLS (inotrope_chronotrope_vasopressor, first line) — AHA 2020 ACLS — standard arrest pathway; in confirmed LQT post-ROSC minimize subsequent infusions because adrenergic load triggers LQT1/2
5. propofol 5–50 µg/kg/min; titrate RASS IV continuous (sedative_iv_anesthetic, first line) — PADIS 2018; preferred sedative in LQT post-arrest because does NOT prolong QT (vs avoiding antipsychotics which do)
6. fentanyl 25–200 µg/h IV continuous (opioid_analgesic, first line) — PADIS 2018; preferred opioid (does NOT prolong QT) over methadone (QT-prolonging — AVOID)
7. dexmedetomidine 0.2–1.4 µg/kg/h; no bolus IV continuous (alpha2_agonist_sedative, second line) — PADIS 2018; preferred for ICU delirium in LQT cohort because does NOT prolong QT (vs haloperidol — AVOID); Class IIa AHA delirium prevention
8. nadolol CONGENITAL LQT1/LQT2 long-term: nadolol 1–1.5 mg/kg/d daily (preferred over propranolol per recent registry data — long half-life + better adherence) PO daily; lifelong (non_selective_beta_blocker_long_acting, comorbidity specific) — HRS 2017 PMID 28219760 Class I + Schwartz International LQTS Registry — mortality reduction in LQT1/2 with long-term β-blocker; nadolol preferred over propranolol (long half-life, daily dosing improves adherence)
9. propranolol CONGENITAL LQT1/LQT2 long-term alternate: propranolol 2–4 mg/kg/d divided BID-QID PO BID-QID; lifelong (non_selective_beta_blocker, comorbidity specific) — HRS 2017 Class I; Schwartz registry — historical first-line; QID dosing reduces adherence vs nadolol daily
10. mexiletine CONGENITAL LQT3 long-term: mexiletine 150–300 mg PO q8h PO TID (class_ib_sodium_channel_blocker, comorbidity specific) — HRS 2017 IIa — mexiletine shortens QT in LQT3 by blocking late INa (the gain-of-function defect); does NOT replace ICD
11. isoproterenol 0.5–2 µg/min IV titrate to HR 90–110 for bradycardia-dependent TdP recurrence (LQT3 + acquired); CONTRAINDICATED in LQT1/2 IV continuous (beta1_agonist, rescue) — AHA 2020 ACLS — increases HR shortens QT prevents R-on-T; useful for bradycardia-dependent TdP (LQT3 + acquired); CONTRAINDICATED in LQT1/2 (adrenergic trigger)
12. acetaminophen 650 mg PO/PR/IV q6h PRN PO/PR/IV q6h PRN (antipyretic_analgesic, first line) — Standard analgesia / antipyresis; does NOT prolong QT

Setting playbook (outpatient) — Long-term EP / inherited-arrhythmia clinic surveillance; ICD interrogation q3–6 mo; β-blocker maintenance + dose optimization; LCSD for refractory β-blocker failure or ICD-shock burden; family cascade testing completion + ongoing identification of newly recognised relatives; lifelong drug-avoidance education + lifestyle modifications; annual mental health screen
13. continue β-blocker maintenance for CONGENITAL LQT1/2 lifelong nadolol 1–1.5 mg/kg/d (preferred) OR propranolol 2–4 mg/kg/d PO daily / BID-QID; lifelong — congenital LQT1/LQT2 (HRS 2017 Class I + Schwartz registry mortality reduction)
14. continue mexiletine for CONGENITAL LQT3 lifelong 150–300 mg PO q8h PO TID; lifelong — confirmed LQT3 (HRS 2017 IIa — shortens QT by blocking late INa)
15. continue lifelong avoidance of all QT-prolonging drugs (www.crediblemeds.org) patient education + curated list n/a lifelong — LQT diagnosis (HRS 2017)

Non-pharmacologic actions:
- EP / inherited-arrhythmia clinic q3–6 mo lifelong
- ICD generator / lead surveillance per device clinic; replacement at end-of-service
- LCSD (left cardiac sympathetic denervation) referral for refractory β-blocker failure or ICD-shock burden (HRS 2017 Class IIa)
- Family cascade testing — ongoing identification of newly recognised relatives (extended pedigree)
- Lifestyle: LQT1 avoid competitive swimming/diving lifelong; LQT2 avoid sudden loud noises (vibrating + light alarms); LQT3 caution sleep alone + consider nocturnal cardiac monitoring; aggressive K repletion if hypokalemic
- Medic-alert bracelet maintenance — "Long QT syndrome — AVOID QT-prolonging drugs"
- Mental health long-term

AVOID / contraindication checks:
- Haloperidol_AVOID_in_lqt_post_arrest (QT prolonging — substitute dexmedetomidine + low dose olanzapine for delirium)
- Ondansetron_above_16mg_cumulative_AVOID_in_lqt (FDA black box; substitute scopolamine patch + low dose olanzapine for nausea)
- Citalopram_above_20mg_AVOID_in_lqt (FDA black box dose dependent QT prolongation; substitute sertraline or mirtazapine)
- Macrolides_azithromycin_erythromycin_clarithromycin_AVOID_in_lqt (substitute doxycycline or β lactam only regimen)
- Fluoroquinolones_moxifloxacin_levofloxacin_ciprofloxacin_AVOID_in_lqt (moxifloxacin > levofloxacin > ciprofloxacin risk; substitute β lactams or aztreonam)
- Methadone_AVOID_in_lqt_post_arrest (QT prolonging; substitute fentanyl + hydromorphone)
- Class_ia_antiarrhythmics_AVOID_in_lqt (quinidine, procainamide, disopyramide further prolong QT)
- Class_iii_antiarrhythmics_AVOID_in_lqt (sotalol, dofetilide, ibutilide further prolong QT and may have caused storm)
- Amiodarone_relative_AVOID_in_lqt (less torsadogenic vs other class III but still QT prolonging — reserve for refractory VT with no alternative)
- Beta_blocker_AVOID_acute_in_bradycardia_dependent_acquired_tdp (slowing rate worsens TdP); ACCEPTABLE / FIRST LINE long term in congenital LQT1/2 (Schwartz registry mortality reduction)
- Isoproterenol_AVOID_in_lqt1_or_lqt2 (adrenergic trigger); ACCEPTABLE for bradycardia dependent LQT3 + acquired
- Lifelong_avoidance_qt_prolonging_drugs_per_crediblemeds (gold standard curated reference)
- Icd_indicated_HRS_2017_class_i_post_lqt_arrest (sustained VT/VF survivor by definition)

Monitoring

Regimen monitoring:
- continuous ecg telemetry x 48-72h with qt measurement q4-6h (HRS 2017)
- serial ecg q4-6h x 24h then q6-8h x 48h (track QTc trend toward < 480 ms)
- BMP q4-6h until K above 4.5 and Mg above 2 sustained (mandatory targets)
- serial troponin q3-6h x 24h (4th UDMI 2018)
- continuous core temp via bladder or esophageal probe during TTM (TTM2 PMID 34133859)
- continuous EEG for 24-48h (Sandroni 2021 PMID 33745427)
- NSE at 24h 48h 72h (Sandroni 2021)
- lactate q2-4h until normalized (SCAI 2022 PMID 35718438)
- daily medication audit against crediblemeds org (lifelong drug avoidance)
- genetic panel kcnq1 kcnh2 scn5a core then expanded if negative (HRS 2017)
- cardiac MRI at 4-6 wk (rule out CPVT / ARVC / infiltrative)
- first degree relative ecg screening referral (cascade testing)

Setting (outpatient) monitoring:
- q3–6 mo ICD interrogation lifelong
- Annual ECG
- Annual Holter if BB titration or symptoms
- Family cascade testing progress documentation
- Lifelong drug audit at every clinic visit (www.crediblemeds.org)

Follow-up plan: Cardiology + EP / inherited-arrhythmia clinic at 2–4 wks; cardiac MRI at 4–6 wk (post-stunning resolution); GENETIC PANEL completed (KCNQ1/KCNH2/SCN5A core; expanded if needed); CASCADE FAMILY SCREENING — first-degree relatives ECG + genotyping at proband mutation; lifelong β-blocker (nadolol preferred); ICD interrogation q3–6 mo; LCSD evaluation for shock burden; lifelong drug avoidance (medic-alert bracelet "Long QT — AVOID QT-prolonging drugs"); LQT1 avoid swimming/diving; LQT2 avoid sudden loud noises (alarm clock modification); LQT3 caution sleep alone + nocturnal monitoring; aggressive K repletion if hypokalemic; PTSD / mental health screen
- Close-out criterion: cardiology + EP follow-up + genetic panel + cascade family screening + ICD + lifelong β-blocker + drug avoidance + lifestyle modification + mental health all booked / documented

Monitoring phase: Continuous telemetry × 48–72 h with QT measurement q4–6 h; multimodal neuroprog ≥72 h post-rewarm (Sandroni 2021 PMID 33745427); serial ECG q4–6 h × 24 h then q6–8 h × 48 h; BMP + Mg q4–6 h until target achieved + sustained; daily ECG until QTc < 480 ms; daily medication audit against www.crediblemeds.org

Disposition

Current setting: outpatient — Long-term EP / inherited-arrhythmia clinic surveillance; ICD interrogation q3–6 mo; β-blocker maintenance + dose optimization; LCSD for refractory β-blocker failure or ICD-shock burden; family cascade testing completion + ongoing identification of newly recognised relatives; lifelong drug-avoidance education + lifestyle modifications; annual mental health screen

Disposition criteria:
- Long-term continuation lifelong; ICD + β-blocker (or mexiletine for LQT3) + LCSD if refractory + lifelong drug avoidance + lifestyle modifications + family cascade testing operational

Escalation triggers (move to higher acuity):
- Recurrent ICD shock → emergent EP + storm investigation; LCSD evaluation
- New QT-prolonging drug exposure → ED + drug withdrawal + reassessment
- Family member positive screening → cascade testing extended + EP referral
- BB intolerance → LCSD evaluation; alternate BB; mexiletine consideration
- Mental health crisis → psychiatry

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Recurrent TdP / polymorphic VT post-ROSC suggests ongoing storm physiology — MgSO4 2 g IV bolus + 2 g/h infusion regardless of measured Mg level; route to sister cardio.cardiogenic-shock.lqt-tdp-storm.v1 for mid-storm hemodynamic + electrical management; AVOID Class IA + III antiarrhythmics
- [LIFE_THREATENING] Bradycardia-dependent TdP recurrence post-ROSC (LQT3 phenotype or acquired with high-grade AV block / sinus arrest / post-cardioversion pause) — isoproterenol 0.5–2 µg/min OR overdrive transcutaneous / transvenous pacing at 80–100 bpm; AVOID β-blockers acutely (long-term lifesaving in LQT1/2 only)
- [SEVERE] Inadvertent administration of QT-prolonging drug post-ROSC (haloperidol, ondansetron > 16 mg, citalopram, macrolide, fluoroquinolone, methadone, Class IA/III antiarrhythmic, antipsychotic) in confirmed or suspected LQT — STOP drug + escalate to EP + chart audit + nursing handoff review; substitute with QT-neutral alternative

Citations

- HRS 2017 Inherited Arrhythmia Syndromes Expert Consensus (Al-Khatib PMID 28219760) + AHA 2020 ACLS / Post-Cardiac-Arrest Care + TTM2 + Sandroni 2021 ERC-ESICM neuroprog + Schwartz International LQTS Registry + ESC 2022 VA / SCD prevention + CredibleMeds (www.crediblemeds.org) curated QT-prolonging drug list (gold standard reference) [PMID:28219760](https://pubmed.ncbi.nlm.nih.gov/28219760/)
- Cited evidence (PMID 33098585) [PMID:33098585](https://pubmed.ncbi.nlm.nih.gov/33098585/)
- Cited evidence (PMID 33081530) [PMID:33081530](https://pubmed.ncbi.nlm.nih.gov/33081530/)
- Cited evidence (PMID 34133859) [PMID:34133859](https://pubmed.ncbi.nlm.nih.gov/34133859/)
- Cited evidence (PMID 31532382) [PMID:31532382](https://pubmed.ncbi.nlm.nih.gov/31532382/)

Last reconciled with current guidelines: 2026-05-15.
References
  • HRS 2017 Inherited Arrhythmia Syndromes Expert Consensus (Al-Khatib PMID 28219760) + AHA 2020 ACLS / Post-Cardiac-Arrest Care + TTM2 + Sandroni 2021 ERC-ESICM neuroprog + Schwartz International LQTS Registry + ESC 2022 VA / SCD prevention + CredibleMeds (www.crediblemeds.org) curated QT-prolonging drug list (gold standard reference) — PMID:28219760
  • Cited evidence (PMID 33098585) — PMID:33098585
  • Cited evidence (PMID 33081530) — PMID:33081530
  • Cited evidence (PMID 34133859) — PMID:34133859
  • Cited evidence (PMID 31532382) — PMID:31532382