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cardio.atrial_flutter.amyloidosis-related.v1

Atrial flutter in cardiac amyloidosis (ATTR-CM and AL)

cardiologyacutechronicadultacuteinpatienttransitionoutpatient
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Phase E variant of cardio.atrial_flutter.v1 — atrial flutter arising from cardiac amyloidosis (ATTR-CM and AL types). Inherits AC + acute rate/rhythm framework from parent; specializes for amyloid-specific drug avoidance (DIGOXIN ABSOLUTELY CONTRAINDICATED; BB poorly tolerated low-dose only; diltiazem cautious) + LAA thrombus surveillance (25–30% incidence vs 5–10% non-amyloid; TEE mandatory pre-cardioversion) + lower CHA2DS2-VASc threshold for AC (Kittleson 2023 PMID 37290437) + ATTR/AL disease-modifying therapy pathway (tafamidis 61 mg daily per ATTR-ACT PMID 30145930; CyBorD/daratumumab per ANDROMEDA for AL). Catheter ablation success lower in amyloid (~50–60% vs >95% non-amyloid CTI) due to diffuse atrial substrate; combined rate control + AC + ATTR therapy often best long-term strategy. Cross-engine routing to cardio.acute-hf.amyloidosis.v1 for ADHF episodes; both engines run in parallel with shared amyloid-specific drug avoidance list. Family screening for ATTRv with genetic counseling obligatory; first-degree relatives offered TTR genotyping. Manifest pointer reuses cardio.atrial_flutter.v1 manifest. Design-brief pointer reuses parent. Status INTEGRATED until terminology + RxNav-validated drug codes are reconciled. Authored 2026-05-15 by shard-06-cardio-acute.

Entry points (5)

  • imaging
    Atrial flutter on ECG/telemetry + LV wall thickness ≥12 mm + no long-standing HTN — amyloidosis screen
    aflutter_with_thick_lv_walls_no_htn
  • imaging
    AFL with low-voltage QRS + thick LV walls (voltage-mass mismatch — amyloid signature)
    aflutter_with_low_voltage_ecg
  • history
    Elderly male with bilateral carpal tunnel release history + new AFL — ATTRwt clue
    elderly_male_aflutter_carpal_tunnel_history
  • imaging
    Apical sparing pattern on speckle-tracking strain echo + AFL (cherry-on-top amyloid signature)
    apical_sparing_strain_with_aflutter
  • history
    Patient with established ATTR-CM or AL amyloidosis presents with new atrial flutter
    known_amyloidosis_with_new_aflutter

Required inputs (19)

  • agerequired
    demographic • used at CONTEXT
    ATTRwt overwhelmingly age >65; AL across ages; ATTRv often presents 30–60 with hereditary mutation; CHA2DS2-VASc + ablation candidacy
  • race_ethnicity
    demographic • used at CONTEXT
    V122I ATTR variant prevalent in West African / African-American descent (~3–4%) — drives variant ATTR screen
  • family_history_neuropathy_or_carpal_tunnel
    history • used at CONTEXT
    ATTRv signal — autonomic + peripheral neuropathy + bilateral carpal tunnel
  • sbprequired
    vital • used at RED_FLAGS
    Hypotension highly common in amyloid (autonomic + restrictive); narrow tolerance for AVN blockers + diuretics
  • hrrequired
    vital • used at CONTEXT
    AFL RVR severity; rate-control target tighter (preserve preload-dependent cardiac output); avoid bradycardia which crashes CO in restrictive physiology
  • nt_probnprequired
    lab • used at INITIAL_WORKUP
    Markedly elevated in amyloid (often >3000 even with normal LVEF); also a Mayo AL staging variable (>1800)
  • troponinrequired
    lab • used at INITIAL_WORKUP
    Persistently elevated in amyloid (myocardial infiltration); Mayo AL stage variable (cTnT >0.025 or hsTnT >40)
  • serum_free_light_chainsrequired
    lab • used at BRANCHING_WORKUP
    MANDATORY before PYP read — rule out AL amyloidosis; difference >18 mg/L abnormal (Mayo AL staging)
  • spep_upep_immunofixationrequired
    lab • used at BRANCHING_WORKUP
    Detect monoclonal protein for AL workup (combined sensitivity ~99% with SFLC)
  • creatinine_egfrrequired
    lab • used at CONTEXT
    Cardiorenal common in amyloid; DOAC dose; tafamidis dose unaffected; patisiran requires baseline LFT/eGFR
  • tshrequired
    lab • used at INITIAL_WORKUP
    Thyrotoxic flutter mimic; reversible cause to exclude before attributing to amyloid
  • echo_strainrequired
    imaging • used at INITIAL_WORKUP
    Apical sparing pattern (preserved apical longitudinal strain with reduced basal strain) — amyloid signature; LV wall thickness + restrictive filling + LA dilation + biatrial dysfunction
  • tee_pre_cardioversion_or_for_thrombus_screenrequired
    imaging • used at BRANCHING_WORKUP
    Mandatory before any cardioversion in amyloidosis-AFL — atrial mechanical dysfunction persists in sinus rhythm; LAA thrombus common (~25–30% in amyloid AFL vs ~5–10% in non-amyloid AFL)
  • pyp_scan_or_embrequired
    imaging • used at BRANCHING_WORKUP
    TTR PYP scan: visual grade 2–3 + H/CL ratio ≥1.5 + negative monoclonal screen → ATTR diagnosis (no biopsy needed); otherwise endomyocardial biopsy with mass spec for definitive typing
  • ttr_genotype
    lab • used at BRANCHING_WORKUP
    Distinguish ATTRwt vs ATTRv after ATTR diagnosis confirmed (drives family screening + gene-silencer eligibility)
  • ecg_12_leadrequired
    imaging • used at INITIAL_WORKUP
    Confirm AFL morphology + rate; look for amyloid signatures (low voltage in limb leads, pseudo-infarct pattern, conduction delays)
  • cha2ds2_vasc_factorsrequired
    history • used at RISK_STRATIFICATION
    CHA2DS2-VASc; in amyloid, many experts anticoagulate even with low CHA2DS2-VASc due to atrial myopathy + intracardiac thrombus risk (Kittleson ACC/AHA 2023 PMID 37290437)
  • bleeding_historyrequired
    history • used at RISK_STRATIFICATION
    HAS-BLED; amyloid patients often have factor X deficiency (AL) or vascular fragility — heightened bleed risk
  • current_medsrequired
    medication • used at CONTEXT
    Critical to identify and DISCONTINUE digoxin if present (absolute contraindication); review BB/CCB tolerance

12-phase flow (12)

  1. 1FRAME
    Atrial flutter in cardiac amyloidosis — three-axis decision: (1) amyloid type (AL vs ATTRwt vs ATTRv) drives disease-modifying therapy; (2) AFL management with AMYLOID-SPECIFIC AVOID list (digoxin contraindicated, BB poorly tolerated, diltiazem cautious); (3) AC strategy (lifelong DOAC, lower CHA2DS2-VASc threshold per Kittleson 2023, TEE mandatory pre-CV). ESC 2023 amyloidosis (PMID 37596926) + ACC/AHA 2024 AF (PMID 38753446) + Kittleson 2023 (PMID 37290437)
    inputs: ecg_12_lead, echo_strain
    advance: amyloidosis-related AFL framework established
  2. 2ENTRY
    AFL on telemetry + amyloid signatures (thick LV walls, low voltage, apical sparing, monoclonal protein, carpal tunnel history) OR known amyloidosis with new AFL
    inputs: age, hr
    advance: engine entered
  3. 3CONTEXT
    Demographics, family history (ATTRv signal), neuropathy, prior monoclonal workup, AFL chronicity + prior AC, current meds (DIGOXIN AUDIT — discontinue if present), baseline functional status, autonomic symptoms (orthostasis), comorbidities
    inputs: hr, cha2ds2_vasc_factors, bleeding_history, current_meds
    advance: context complete + digoxin discontinued if present
  4. 4RED_FLAGS
    Hemodynamic instability (SBP <90 with AFL RVR or AVN-blocker-induced — DCCV with EXTRA caution given atrial myopathy thrombus risk; TEE first if possible); digoxin toxicity if previously prescribed (life-threatening in amyloid); rapidly rising free light chains in AL with cardiac stage III–IV (oncologic emergency); ventricular arrhythmia from amyloid infiltration; severe orthostasis from BB intolerance
    inputs: sbp, troponin, nt_probnp
    actions: tachycardia
    advance: red flags screened or escalated
  5. 5INITIAL_WORKUP
    NT-proBNP + troponin + BMP + ECG (low voltage, pseudo-infarct, AFL morphology) + echo with strain (apical sparing) + TSH (rule out thyrotoxic mimic) + CXR + 12-lead
    inputs: nt_probnp, troponin, echo_strain, tsh, ecg_12_lead, creatinine_egfr
    actions: acs_pathway, panel.cardiac, panel.thyroid, panel.renal
    advance: baseline workup documented
  6. 6BRANCHING_WORKUP
    AL screen FIRST (SPEP + UPEP + immunofixation + serum free light chains) — if positive route to hematology emergent + ROUTE TO cardio.acute-hf.amyloidosis.v1; if AL screen negative → TTR PYP scan; if PYP positive → ATTR diagnosed (no biopsy needed); if PYP negative + suspicion remains → endomyocardial biopsy with mass spectrometry typing; TTR genotyping post-ATTR diagnosis (ATTRwt vs ATTRv); TEE MANDATORY pre-cardioversion (LAA thrombus 25–30% in amyloid AFL); concomitant AF detection on monitor → cardio.afib.core.v1
    inputs: serum_free_light_chains, spep_upep_immunofixation, pyp_scan_or_emb, tee_pre_cardioversion_or_for_thrombus_screen
    actions: afib_new_onset
    advance: amyloid type definitively assigned + LAA thrombus screen completed
  7. 7DIFFERENTIAL
    AFL from amyloid vs AFL with coincidental amyloid; AL vs ATTRwt vs ATTRv (drives therapy completely); amyloid vs HOCM vs hypertensive heart vs Fabry vs sarcoidosis (echo + PYP + biopsy)
    inputs: pyp_scan_or_emb
    advance: amyloid type assigned + mimics excluded
  8. 8RISK_STRATIFICATION
    Mayo AL stage (NT-proBNP, troponin, dFLC); ATTR NAC stage (NT-proBNP + eGFR); CHA2DS2-VASc (lower threshold for AC in amyloid per Kittleson 2023 PMID 37290437); HAS-BLED (factor X deficiency in AL increases bleed risk); NYHA class — drives tafamidis benefit estimation
    inputs: cha2ds2_vasc_factors, bleeding_history, nt_probnp, troponin
    actions: calc.cha2ds2vasc, calc.has_bled
    advance: amyloid stage + AC tier documented
  9. 9TREATMENT
    AFL rate control with AMYLOID-SPECIFIC PROTOCOL: (1) AVOID DIGOXIN ABSOLUTELY (binds amyloid fibrils); (2) low-dose BB cautiously (metoprolol 12.5 mg PO daily start, watch SBP/orthostasis); (3) low-dose diltiazem if BB intolerant + EF preserved (CAUTIOUS — also binds amyloid); (4) AC with DOAC at standard dose (apixaban 5 mg BID; ARISTOTLE PMID 21870978) — many experts AC even at low CHA2DS2-VASc due to atrial myopathy thrombus risk per Kittleson 2023 (PMID 37290437); (5) TEE mandatory before any cardioversion (LAA thrombus ~25–30% in amyloid AFL); (6) catheter ablation lower success rate (~50–60% vs >95% in non-amyloid CTI) — diffuse substrate; (7) ATTR-specific therapy: tafamidis 61 mg PO daily (ATTR-ACT PMID 30145930) ± gene-silencer; (8) AL: emergent hematology for CyBorD or daratumumab + ROUTE TO cardio.acute-hf.amyloidosis.v1
    inputs: sbp, creatinine_egfr, tee_pre_cardioversion_or_for_thrombus_screen
    advance: amyloid-specific rate control + AC + disease-modifying therapy + TEE-cleared CV plan documented
  10. 10DISPOSITION
    Floor vs ICU; AL with cardiac stage III–IV → ICU + hematology; ATTR with stable AFL + tafamidis initiation → step-down/floor; coordinate with amyloidosis center where available
    advance: unit + multidisciplinary team assigned
  11. 11MONITORING
    Telemetry continuous for AFL + arrhythmia + AVN-blocker tolerance; daily orthostasis check; serial NT-proBNP for amyloid trend; AL: monitor FLC weekly during chemotherapy; ATTR: NT-proBNP + 6MWD + echo at 6 mo on tafamidis; LAA thrombus surveillance with repeat TEE in 4–6 weeks if AFL persists
    inputs: ecg_12_lead, creatinine_egfr, nt_probnp
    actions: panel.renal, panel.cardiac
    advance: amyloid + AFL monitoring plan documented
  12. 12FOLLOWUP
    Amyloidosis center referral; cardiology + EP for ablation candidacy assessment (lower success expected); hematology for AL; genetic counseling for ATTRv; lifelong DOAC; tafamidis lifelong for ATTR; periodic echo + NT-proBNP for disease progression
    advance: amyloidosis-specific follow-up booked + family screening initiated for ATTRv