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cardio.aortic-stenosis.low-flow-low-gradient.v1PRODUCTION
cardio.aortic-stenosis.low-flow-low-gradient.v1

Low-flow low-gradient severe aortic stenosis (classical + paradoxical)

cardiologychronicadult
Hard-required inputs
0 / 8
Care setting:

Encounter flow

12/12 authored

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

Current phase

Frame

Detailed

Confirm LFLG pattern; classical (LVEF <50%) vs paradoxical (LVEF ≥50%)

Inputs
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Actions
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Advance rule
Set
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LFLG phenotype assigned

Patient inputs (12)

CT aortic-valve calcium score thresholds are sex-specific (men ≥2000, women ≥1200–1300 AU)

LVEF <50% = classical LFLG; ≥50% = paradoxical LFLG — different pathways

AVA ≤1.0 cm² is the severity gate that conflicts with the low gradient

<40 mmHg defines the low-gradient discordance

SVi <35 mL/m² defines the low-flow state

Surgical risk + SAVR vs TAVR decision

Symptomatic true-severe LFLG = AVR indication

Contrast for CT calcium / coronary / TAVR planning

Dobutamine stress echo: contractile reserve + true-vs-pseudo severe (classical)

CT Agatston score adjudicates severity when DSE inconclusive / paradoxical

Small restrictive LV + low voltage / neuropathy / carpal tunnel → ATTR screen

AF + MR worsen the low-flow state and confound severity assessment

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

Severity triggers (9)

9 need judgement
  • informationallife_threateningdecompensated_low_output
    Decompensated low-output state in classical LFLG — cautious stabilisation; AVR (often TAVR) may be definitive therapy — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereclassical_lflg_true_severe
    Classical LFLG (LVEF <50%) true-severe on DSE (AVA ≤1.0 persists, gradient >40 with flow) — Class I AVR even without contractile reserve — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereno_contractile_reserve_branch
    Classical LFLG without contractile reserve on DSE — highest surgical risk; TAVR-leaning; CT calcium adjudicates severity — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereattr_amyloid_overlap_branch
    Small restrictive LV + low ECG voltage + carpal tunnel/neuropathy in paradoxical LFLG — screen ATTR (PYP + SFLC); ATTR-AS overlap changes prognosis + adds tafamidis — amyloid phenocopy
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateparadoxical_lflg_branch
    Paradoxical LFLG (LVEF ≥50%, small hypertrophied/restrictive LV, SVi <35) — sex-specific CT calcium adjudication + exclude measurement error — Class IIa AVR if true-severe symptomatic — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateaf_confounder_branch
    Concurrent AF worsening the low-flow state — rate/rhythm control + AC; reassess severity in sinus / controlled rate — ESC 2024 AF
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateckd_special_pop
    CKD — minimise contrast for CT calcium/coronary/TAVR planning; renal-adjust peri-procedural meds — KDIGO 2024
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateelderly_frailty_branch
    Elderly/frail true-severe LFLG — TAVR-leaning; frailty + futility assessment by heart-team — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildpseudo_severe_branch
    AVA opens >1.0 cm² with flow normalisation on DSE — pseudo-severe; manage as moderate AS, do NOT operate; serial surveillance — 2020 ACC/AHA VHD
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

LFLG AS — adjudicate true-vs-pseudo then AVR decision (2020 ACC/AHA VHD)
axis: lflg_as_adjudicate_then_avrstep 1 - Step 1 — Adjudicate severity (diagnostic, no AVR commitment yet)
Selected step "Step 1 — Adjudicate severity (diagnostic, no AVR commitment yet)" — AVA ≤1.0 cm² with discordant low gradient
  • dobutamine stress echocardiography (classical LFLG)
    first line
    diagnostic
    triggers: classical_LFLG_LVEF_lt_50
    DSE distinguishes true-severe (AVA ≤1.0 persists, gradient >40 with flow) from pseudo-severe (AVA opens >1.0) and assesses contractile reserve (2020 ACC/AHA VHD)
  • CT aortic-valve calcium score (Agatston, sex-specific)
    first line
    diagnostic
    triggers: paradoxical_LFLG, DSE_inconclusive
    Sex-specific thresholds (men ≥2000 AU, women ≥1200–1300 AU) adjudicate severity flow-independently (2020 ACC/AHA VHD)
  • ATTR amyloid screen (99mTc-PYP + serum/urine free light chains)
    comorbidity specific
    diagnostic
    triggers: small_restrictive_LV, low_voltage_ECG, carpal_tunnel_or_neuropathy
    Paradoxical LFLG with restrictive small LV — exclude ATTR-CM phenocopy/overlap (changes prognosis + adds tafamidis pathway)

outpatient playbook — drug actions (2)

  1. 1. diagnostic adjudication (DSE / CT Ca / ATTR screen)
    n/a • n/a • n/a
    trigger: Discordant LFLG (2020 ACC/AHA VHD)
    Resolve severity before AVR commitment
  2. 2. GDMT for classical HFrEF component
    per HFrEF protocol (cautious pre-AVR) • PO • per drug
    trigger: Classical LFLG with HFrEF (2022 ACC/AHA HF)
    Co-manage HFrEF; optimise post-AVR

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Echo: AVA ≤1.0 cm² with mean gradient <40 mmHg / Vmax <4 m/s (discordant); Echo: stroke volume index <35 mL/m² (low-flow state); Exertional dyspnea / syncope / angina with discordant AS.

Objective

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

Assessment

**Low-flow low-gradient severe aortic stenosis (classical + paradoxical)** (cardio.aortic-stenosis.low-flow-low-gradient.v1).
Phenotype framing: True-severe vs pseudo-severe vs normal-flow low-gradient vs measurement error vs ATTR-CM phenocopy
Scope: Confirm LFLG pattern; classical (LVEF <50%) vs paradoxical (LVEF ≥50%)

No severity triggers fired against current inputs.

Plan

Regimen axis: **LFLG AS — adjudicate true-vs-pseudo then AVR decision (2020 ACC/AHA VHD)** — step "Step 1 — Adjudicate severity (diagnostic, no AVR commitment yet)".
1. dobutamine stress echocardiography (classical LFLG) (diagnostic, first line) — DSE distinguishes true-severe (AVA ≤1.0 persists, gradient >40 with flow) from pseudo-severe (AVA opens >1.0) and assesses contractile reserve (2020 ACC/AHA VHD)
2. CT aortic-valve calcium score (Agatston, sex-specific) (diagnostic, first line) — Sex-specific thresholds (men ≥2000 AU, women ≥1200–1300 AU) adjudicate severity flow-independently (2020 ACC/AHA VHD)
3. ATTR amyloid screen (99mTc-PYP + serum/urine free light chains) (diagnostic, comorbidity specific) — Paradoxical LFLG with restrictive small LV — exclude ATTR-CM phenocopy/overlap (changes prognosis + adds tafamidis pathway)

Setting playbook (outpatient) — Adjudicate true-vs-pseudo severe LFLG, screen ATTR in paradoxical, refer true-severe symptomatic for AVR (2020 ACC/AHA VHD)
4. diagnostic adjudication (DSE / CT Ca / ATTR screen) n/a n/a n/a — Discordant LFLG (2020 ACC/AHA VHD) (Resolve severity before AVR commitment)
5. GDMT for classical HFrEF component per HFrEF protocol (cautious pre-AVR) PO per drug — Classical LFLG with HFrEF (2022 ACC/AHA HF) (Co-manage HFrEF; optimise post-AVR)

Non-pharmacologic actions:
- Heart-team referral for true-severe symptomatic LFLG (SAVR vs TAVR) — 2020 ACC/AHA VHD
- Route to ATTR-CM engine if PYP grade 2–3 + negative SFLC — amyloid pathway
- Manage pseudo-severe as moderate AS with serial surveillance — 2020 ACC/AHA VHD

AVOID / contraindication checks:
- Avoid aggressive afterload reduction in fixed severe AS pre AVR — 2020 ACC/AHA VHD
- Do not deny AVR in classical LFLG without contractile reserve still benefits — 2020 ACC/AHA VHD
- Screen ATTR before labeling paradoxical LFLG — amyloid phenocopy
- Pseudo severe AS managed as moderate not operated — 2020 ACC/AHA VHD

Monitoring

Regimen monitoring:
- serial TTE AVA gradient SVi LVEF — 2020 ACC/AHA VHD
- reassess flow state after GDMT and AF rate control — 2020 ACC/AHA VHD
- CT calcium score when DSE inconclusive — 2020 ACC/AHA VHD
- post-AVR TTE baseline then annually — 2020 ACC/AHA VHD
- BNP trend — 2022 ACC/AHA HF

Setting (outpatient) monitoring:
- Serial TTE; reassess flow after GDMT/AF control — 2020 ACC/AHA VHD
- Symptom review each visit — 2020 ACC/AHA VHD

Follow-up plan: Post-AVR surveillance; route to ATTR-CM engine if amyloid confirmed; HFrEF engine for classical component
- Close-out criterion: follow-up + escalation triggers documented

Monitoring phase: Serial TTE; reassess flow state after GDMT/AF control

Disposition

Current setting: outpatient — Adjudicate true-vs-pseudo severe LFLG, screen ATTR in paradoxical, refer true-severe symptomatic for AVR (2020 ACC/AHA VHD)

Disposition criteria:
- Pseudo-severe → moderate-AS surveillance
- True-severe symptomatic → AVR (SAVR/TAVR) referral
- ATTR overlap → ATTR-CM engine + valve heart-team

Escalation triggers (move to higher acuity):
- True-severe symptomatic LFLG → AVR referral now — 2020 ACC/AHA VHD
- Decompensation/low-output → ED + acute HF pathway; expedite AVR — 2020 ACC/AHA VHD
- PYP-positive ATTR → route cardio ATTR-CM engine — amyloid pathway

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Decompensated low-output state in classical LFLG — cautious stabilisation; AVR (often TAVR) may be definitive therapy — 2020 ACC/AHA VHD
- [SEVERE] Classical LFLG (LVEF <50%) true-severe on DSE (AVA ≤1.0 persists, gradient >40 with flow) — Class I AVR even without contractile reserve — 2020 ACC/AHA VHD
- [SEVERE] Classical LFLG without contractile reserve on DSE — highest surgical risk; TAVR-leaning; CT calcium adjudicates severity — 2020 ACC/AHA VHD

Citations

- 2020 ACC/AHA VHD Guideline + 2021 ESC/EACTS VHD Guideline [PMID:33332149](https://pubmed.ncbi.nlm.nih.gov/33332149/)
- Cited evidence (PMID 34453165) [PMID:34453165](https://pubmed.ncbi.nlm.nih.gov/34453165/)
- Cited evidence (PMID 27040324) [PMID:27040324](https://pubmed.ncbi.nlm.nih.gov/27040324/)
- Cited evidence (PMID 30883058) [PMID:30883058](https://pubmed.ncbi.nlm.nih.gov/30883058/)
- Cited evidence (PMID 29268916) [PMID:29268916](https://pubmed.ncbi.nlm.nih.gov/29268916/)

Last reconciled with current guidelines: 2026-05-16.
References