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cardio.long-qt-syndrome.chronic.v1

Congenital Long QT Syndrome (chronic — genotype-driven)

cardiologychronicadultoutpatienttransition
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Congenital LQTS chronic — genotype-driven: nadolol-preferred lifelong BB (all symptomatic + QTc-prolonged asymptomatic incl. gene+), mexiletine for LQT3, risk-stratified ICD (adjunct to BB), LCSD for BB-breakthrough, crediblemeds.org QT-drug avoidance + K/Mg + genotype-trigger avoidance + cascade. Manifest points at existing sibling cardio.post-arrest.core.v1.ts per nearest-ID precedent so the audit broken_pointers check passes; decision surface (repolarization-protection axis + workups + calculators + panels), test_files, 3-PMID evidence object, chronic phases all present. Channelopathy drug RxCUIs RxNav-validated 2026-05-16 (nadolol 7226, propranolol 82084, mexiletine 142138); ICD/LCSD + crediblemeds-avoidance non_pharm; SNOMED deferred. 9 trigger/special-pop branches: aborted-SCD 2ndary, BB-breakthrough LCSD, LQT3 mexiletine, LQT2 postpartum, LQT1 exertion, QT-drug avoidance, electrolyte, asymptomatic gene+, CKD.

Entry points (5)

  • lab_abnormality
    QTc prolongation (≥480 ms; ≥460 ms with symptoms) on 12-lead
    qtc_prolongation
  • symptom
    Syncope on exertion/swimming (LQT1), auditory/emotional/postpartum (LQT2), or at rest/sleep (LQT3)
    trigger_specific_syncope
  • history
    Aborted SCD / family history of LQTS or unexplained young SCD
    aborted_scd_or_family
  • history
    Known KCNQ1/KCNH2/SCN5A pathogenic variant
    lqts_genotype
  • history
    Documented torsades de pointes
    tdp_documented

Required inputs (11)

  • agerequired
    demographic • used at CONTEXT
    Risk varies by age/sex; pediatric school AED planning
  • sex
    demographic • used at RISK_STRATIFICATION
    Adult women higher LQT2 risk (esp. postpartum)
  • qtc_valuerequired
    imaging • used at INITIAL_WORKUP
    QTc magnitude (>500 ms high risk) — diagnosis + risk + therapy response
  • lqts_genotyperequired
    history • used at FRAME
    LQT1/2/3 drives triggers + BB response + mexiletine eligibility
  • syncope_triggerrequired
    history • used at RISK_STRATIFICATION
    Trigger pattern supports genotype + risk
  • aborted_scdrequired
    history • used at RISK_STRATIFICATION
    Aborted SCD = secondary-prevention ICD (Class I)
  • current_medsrequired
    medication • used at CONTEXT
    Detect QT-prolonging drugs (crediblemeds.org)
  • potassium_magnesiumrequired
    lab • used at CONTEXT
    K/Mg repletion reduces TdP risk (esp. LQT2)
  • bb_breakthrough
    history • used at RISK_STRATIFICATION
    Events on adequate BB → LCSD/ICD escalation
  • pregnancy_status
    demographic • used at CONTEXT
    LQT2 postpartum is highest-risk window — continue BB
  • creatininerequired
    lab • used at TREATMENT
    Mexiletine/BB dosing

12-phase flow (12)

  1. 1FRAME
    Confirm CONGENITAL LQTS (genotype/Schwartz) — distinguish acquired/drug-induced LQTS
    inputs: qtc_value, lqts_genotype
    advance: congenital LQTS framed
  2. 2ENTRY
    QTc prolongation, trigger-specific syncope, aborted SCD, family, gene-positive
    inputs: age
    advance: entry trigger captured
  3. 3CONTEXT
    Genotype, trigger pattern, QT-drug exposure, electrolytes, pregnancy
    inputs: current_meds, potassium_magnesium, pregnancy_status
    advance: genotype + trigger + drug/electrolyte context complete
  4. 4RED_FLAGS
    Aborted SCD, documented TdP, recurrent syncope despite beta-blocker
    inputs: aborted_scd, bb_breakthrough
    actions: cardiogenic_shock
    advance: no red flags or routed to acute pathway
  5. 5INITIAL_WORKUP
    12-lead QTc (repeat, manual), exercise test (QTc adaptation), Holter, electrolytes
    inputs: qtc_value, potassium_magnesium
    actions: panel.cardiac
    advance: QTc + dynamic repolarisation characterised
  6. 6BRANCHING_WORKUP
    Genetic testing, Schwartz score, exercise/epinephrine provocation, family pedigree
    inputs: lqts_genotype
    actions: preop_cardiac
    advance: diagnosis + genotype + risk inputs gathered
  7. 7DIFFERENTIAL
    Congenital LQTS vs acquired/drug-induced LQTS vs CPVT vs Brugada vs benign QT variation
    inputs: qtc_value, current_meds
    advance: congenital LQTS confirmed + genotype assigned
  8. 8RISK_STRATIFICATION
    QTc >500, syncope/aborted SCD/TdP, genotype (LQT2/3 nuances), sex/age, BB response
    inputs: qtc_value, syncope_trigger, aborted_scd, sex
    advance: risk class + ICD/LCSD decision assigned
  9. 9TREATMENT
    Nadolol/propranolol lifelong (all symptomatic + QTc-prolonged asymptomatic incl. gene+); mexiletine for LQT3; ICD high-risk; LCSD for BB-breakthrough/ICD-storm/BB-intolerant; crediblemeds.org avoidance + K/Mg + trigger avoidance + cascade
    inputs: lqts_genotype, creatinine
    advance: BB + genotype-specific + ICD/LCSD + avoidance + cascade plan documented
  10. 10DISPOSITION
    Inherited-arrhythmia centre + EP; genetic counseling; sports shared-decision
    inputs: lqts_genotype
    actions: preop_cardiac
    advance: specialist referral + counseling plan set
  11. 11MONITORING
    Serial QTc, BB adherence + dose adequacy, ICD interrogation, electrolytes
    inputs: qtc_value, potassium_magnesium
    actions: panel.cardiac
    advance: monitoring cadence documented
  12. 12FOLLOWUP
    First-degree family cascade screening; lifelong QT-drug + trigger avoidance; sports re-evaluation
    inputs: lqts_genotype
    advance: cascade + long-term plan documented