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cardio.cardiogenic-shock.lyme-carditis.v1PRODUCTION
cardio.cardiogenic-shock.lyme-carditis.v1

Cardiogenic shock / high-grade AV block — Lyme carditis

cardiologyacuteadult
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11/12 authored

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

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Detailed

Confirm Lyme carditis as the etiology of conduction collapse / pump failure — endemic region + tick exposure + fluctuating-degree AV block in young/middle-aged previously healthy adult; identify whether presentation is conduction-only (most common) vs combined conduction + myocarditis with shock (rare but recoverable)

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Lyme carditis confirmed as working diagnosis with sub-phenotype (conduction vs myocarditis-shock) stated

Patient inputs (17)

Most cases in 20-50 year-olds; older patients may have higher baseline AV node dysfunction confounding diagnosis

Baseline renal function for ceftriaxone (no dose adjust) vs other agents; cardio-renal monitoring

Endemic region + outdoor exposure + warm-season timing supports diagnosis; only 50-70% recall bite or rash

Drives antibiotic selection — ceftriaxone vs IV doxycycline alternative if anaphylaxis-class beta-lactam allergy

Pulm congestion if myocarditis-driven LV dysfunction; intubation rarely needed

Mildly-to-moderately elevated in Lyme carditis; helps gauge myocardial involvement vs pure conduction system disease

Elevated if LV dysfunction component; trends recovery on antibiotics

Two-tier ELISA → Western blot (IgM early, IgG established); modified two-tier per CDC 2019 update; obtain at admission and at 4-6 weeks if initial negative + clinical suspicion high

Modified Duke criteria exclusion — rule out infective endocarditis as alternative cause of AV block (aortic root abscess) and shock

Diagnostic anchor — fluctuating-degree AV block (1st-degree → Mobitz II → CHB); document conduction status hour-to-hour during acute phase

LV function, RV strain, pericardial effusion, valvular function (rule out IE), wall motion abnormalities

Pulmonary congestion if myocarditis-driven LV dysfunction; cardiac silhouette typically normal

SCAI 2022 staging baseline; symptomatic bradycardia + SBP <90 = pacing + vasopressor indication

CHB with escape rate <40 = high-risk; defines symptomatic bradycardia threshold for temporary pacing

Late gadolinium enhancement pattern of myocarditis if diagnosis uncertain or for prognostication; not required for treatment initiation

Pathognomonic if bull's-eye rash present in past weeks-months; absence does not rule out diagnosis

Headache / cranial nerve palsy / radiculopathy → CSF analysis for concurrent Lyme meningitis (changes antibiotic duration to 2-4 weeks IV)

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

Severity triggers (5)

5 need judgement
  • informationallife_threateningrefractory_av_block_needing_temporary_transvenous_pacer
    High-grade AV block (Mobitz II / CHB) with symptomatic bradycardia / hypotension refractory to atropine — temporary transvenous pacing needed; usually resolves within days-weeks of antibiotics
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningfulminant_lyme_myocarditis_with_cardiogenic_shock
    Rare fulminant Lyme myocarditis variant with severe LV dysfunction + shock physiology — needs full CS support but recovery typically excellent with antibiotics if bridged
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverelyme_carditis_without_tick_history_atypical
    Lyme carditis presentation in patient WITHOUT recalled tick bite or erythema migrans rash (50-70% recall, 30-50% do not) — diagnosis relies on epidemiologic context + serology + clinical pattern
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveresevere_penicillin_allergy_requires_doxycycline_iv_switch
    Severe penicillin/cephalosporin allergy (anaphylaxis-class) precludes ceftriaxone — switch to IV doxycycline 200 mg q12h × 14-21 days
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatelate_stage_lyme_with_persistent_post_treatment_symptoms
    Persistent symptoms (fatigue, arthralgia, cognitive complaints) at 6+ months post-treatment — post-treatment Lyme disease syndrome (PTLDS); NOT an indication for prolonged antibiotic courses per IDSA 2021
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Lyme carditis with AV block / cardiogenic shock — antibiotics cure underlying infection; temporary pacing bridges conduction recovery; CS support if fulminant myocarditis component
axis: lyme_carditis_av_block_phenotype
Selected axis "Lyme carditis with AV block / cardiogenic shock — antibiotics cure underlying infection; temporary pacing bridges conduction recovery; CS support if fulminant myocarditis component" by default fallback (first axis)
  • ceftriaxone
    first line
    cephalosporin_3rd_gen
    2 g IV q24h × 14-21 days (28 days if concurrent neuro Lyme) • IV • q24h
    triggers: high_grade_av_block_with_lyme_carditis, hospitalized_carditis, concurrent_neuro_symptoms
    IDSA 2021 Lyme guideline (Lantos PMID 33417672) strong recommendation for parenteral therapy in high-grade AV block / hospitalized carditis; standard 14-21 days, extend to 28 days if concurrent neuroborreliosis
    rxcui 2193
  • doxycycline
    first line
    tetracycline
    100 mg PO BID × 14-21 days; 200 mg IV q12h alternative if PO not tolerated • PO/IV • BID
    triggers: mild_conduction_lyme_outpatient, pr_lt_300_ms_asymptomatic, penicillin_anaphylaxis_history
    IDSA 2021 outpatient option for mild Lyme carditis (1st-degree AV block, asymptomatic, PR <300 ms); IV doxycycline alternative if severe penicillin allergy precludes ceftriaxone (Wormser PMID 12767092 erythema migrans equivalence anchor)
    rxcui 3640
  • norepinephrine
    second line
    vasopressor_alpha
    0.05–0.5 µg/kg/min titrate MAP ≥65 • IV • continuous
    triggers: fulminant_lyme_myocarditis_with_cs, shock_refractory_to_pacing
    SOAP-II PMID 20200382 — NE first-line vasopressor in CS; rare in Lyme carditis but used in fulminant myocarditis variant
    rxcui 7512
  • dobutamine
    second line
    inotrope_beta1
    2.5–10 µg/kg/min titrate • IV • continuous
    triggers: low_cardiac_output_with_lyme_myocarditis, lv_dysfunction_with_shock
    Inotropic support in fulminant Lyme myocarditis variant with LV dysfunction; CAUTION — may exacerbate ventricular arrhythmias in active myocarditis
    rxcui 3616
  • furosemide
    add on
    loop_diuretic
    40–80 mg IV bolus then titrate • IV • bolus or continuous
    triggers: pulmonary_congestion_with_lyme_myocarditis, volume_overload_with_adequate_perfusion
    Decongest if pulm congestion from myocarditis-related LV dysfunction (ESC 2021 acute HF)
    rxcui 4603
  • atropine
    rescue
    anticholinergic
    0.5 mg IV q3-5 min up to 3 mg total • IV • PRN
    triggers: symptomatic_bradycardia_pre_pacing, high_grade_av_block_pre_temporary_pacer
    2018 ACC/AHA Bradycardia Guideline (Kusumoto PMID 30412705) — atropine first-line pharmacologic for symptomatic bradycardia; bridge until temporary pacing available; LIMITED efficacy in infranodal block (CHB) but worth attempting
    rxcui 1223

outpatient playbook — drug actions (2)

  1. 1. taper GDMT if EF recovered
    gradual taper if EF normalized for ≥3 months • PO • as scheduled
    trigger: Sustained LV recovery from myocarditis component
    Lyme myocarditis usually fully reversible; GDMT often time-limited unlike chronic HFrEF
  2. 2. doxycycline 200 mg single dose for future Ixodes attachment ≥36 h
    rxcui 3640
    200 mg PO once • PO • one dose
    trigger: Future high-risk tick attachment
    IDSA 2021 post-exposure prophylaxis recommendation

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: New high-grade AV block (Mobitz II / CHB) in patient from endemic region with tick exposure or erythema migrans → Lyme carditis until proven otherwise; Fluctuating-degree AV block (1st-degree → Mobitz I → CHB hour-to-hour) in previously healthy young/middle-aged adult — pathognomonic for Lyme carditis; Recent erythema migrans rash + new palpitations / syncope / dyspnea → Lyme carditis evaluation with ECG + echo + serology.

Objective

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

Assessment

**Cardiogenic shock / high-grade AV block — Lyme carditis** (cardio.cardiogenic-shock.lyme-carditis.v1).
Scope: Confirm Lyme carditis as the etiology of conduction collapse / pump failure — endemic region + tick exposure + fluctuating-degree AV block in young/middle-aged previously healthy adult; identify whether presentation is conduction-only (most common) vs combined conduction + myocarditis with shock (rare but recoverable)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Lyme carditis with AV block / cardiogenic shock — antibiotics cure underlying infection; temporary pacing bridges conduction recovery; CS support if fulminant myocarditis component**.
1. ceftriaxone 2 g IV q24h × 14-21 days (28 days if concurrent neuro Lyme) IV q24h (cephalosporin_3rd_gen, first line) — IDSA 2021 Lyme guideline (Lantos PMID 33417672) strong recommendation for parenteral therapy in high-grade AV block / hospitalized carditis; standard 14-21 days, extend to 28 days if concurrent neuroborreliosis
2. doxycycline 100 mg PO BID × 14-21 days; 200 mg IV q12h alternative if PO not tolerated PO/IV BID (tetracycline, first line) — IDSA 2021 outpatient option for mild Lyme carditis (1st-degree AV block, asymptomatic, PR <300 ms); IV doxycycline alternative if severe penicillin allergy precludes ceftriaxone (Wormser PMID 12767092 erythema migrans equivalence anchor)
3. norepinephrine 0.05–0.5 µg/kg/min titrate MAP ≥65 IV continuous (vasopressor_alpha, second line) — SOAP-II PMID 20200382 — NE first-line vasopressor in CS; rare in Lyme carditis but used in fulminant myocarditis variant
4. dobutamine 2.5–10 µg/kg/min titrate IV continuous (inotrope_beta1, second line) — Inotropic support in fulminant Lyme myocarditis variant with LV dysfunction; CAUTION — may exacerbate ventricular arrhythmias in active myocarditis
5. furosemide 40–80 mg IV bolus then titrate IV bolus or continuous (loop_diuretic, add on) — Decongest if pulm congestion from myocarditis-related LV dysfunction (ESC 2021 acute HF)
6. atropine 0.5 mg IV q3-5 min up to 3 mg total IV PRN (anticholinergic, rescue) — 2018 ACC/AHA Bradycardia Guideline (Kusumoto PMID 30412705) — atropine first-line pharmacologic for symptomatic bradycardia; bridge until temporary pacing available; LIMITED efficacy in infranodal block (CHB) but worth attempting

Setting playbook (outpatient) — 1 month + 3 months follow-up — confirm sustained conduction recovery + LV recovery + symptom resolution; tick-bite prevention reinforcement; rare permanent pacer evaluation only if persistent conduction abnormality at 6 weeks
7. taper GDMT if EF recovered gradual taper if EF normalized for ≥3 months PO as scheduled — Sustained LV recovery from myocarditis component (Lyme myocarditis usually fully reversible; GDMT often time-limited unlike chronic HFrEF)
8. doxycycline 200 mg single dose for future Ixodes attachment ≥36 h 200 mg PO once PO one dose — Future high-risk tick attachment (IDSA 2021 post-exposure prophylaxis recommendation)

Non-pharmacologic actions:
- Annual influenza + pneumococcal + COVID-19 vaccination
- Reinforce tick-bite prevention every visit during peak season
- Cards/EP follow-up only if persistent abnormality

AVOID / contraindication checks:
- Doxycycline_avoid_in_pregnancy_and_children_under_8 (tooth staining + bone effects)
- Ceftriaxone_caution_severe_penicillin_anaphylaxis (cross reactivity ~1 2%; consider doxycycline IV alternative)
- Permanent_pacemaker_AVOID_in_acute_lyme_carditis_window (conduction recovers in 90%+ with antibiotics within days weeks per IDSA 2021)
- Qt_prolonging_drugs_avoid_during_bradycardia (TdP risk)
- Beta_blocker_AVOID_during_high_grade_av_block (worsens block)
- Ccb_non_dihydropyridine_AVOID_during_high_grade_av_block (worsens block)
- Digoxin_AVOID_during_high_grade_av_block (worsens block)
- Steroid_routine_use_NOT_recommended_in_lyme_carditis (no clear benefit; antibiotic alone is curative per IDSA 2021)

Monitoring

Regimen monitoring:
- continuous telemetry until conduction normalized (IDSA 2021)
- daily ECG with PR documentation (track resolution)
- daily troponin and BNP trend (myocarditis component)
- serial echo at 48-72h to confirm LV recovery if myocarditis (track recovery)
- weekly LFT and CBC during ceftriaxone course (drug toxicity surveillance)
- lyme serology repeat at 4-6 weeks if initial negative (seroconversion confirmation)
- follow-up ECG at 1 month and 3 months (recovery confirmation)
- follow-up echo at 3 months if myocarditis component (LV recovery)
- consider pacer evaluation only if persistent block at 6 weeks (rare)

Setting (outpatient) monitoring:
- ECG at 1 month + 3 months
- Echo at 3 months if myocarditis
- Symptom screen at every visit

Follow-up plan: Repeat ECG + echo at 1 month + 3 months post-completion; cardiology / EP follow-up if persistent conduction abnormality at 6 weeks (pacer evaluation); ID follow-up for concurrent Lyme features (arthritis, neuro); tick-bite prevention counseling; consider single-dose doxycycline 200 mg post-exposure prophylaxis future Ixodes attachments ≥36 h per IDSA 2021
- Close-out criterion: Follow-up booked + recovery confirmation echo / ECG scheduled + prevention counseling completed

Monitoring phase: Continuous telemetry until conduction normalizes; daily ECG documentation; daily troponin + BNP trend; LFT + CBC weekly during ceftriaxone; serial echo at 48-72 h to confirm LV recovery if myocarditis component

Disposition

Current setting: outpatient — 1 month + 3 months follow-up — confirm sustained conduction recovery + LV recovery + symptom resolution; tick-bite prevention reinforcement; rare permanent pacer evaluation only if persistent conduction abnormality at 6 weeks

Disposition criteria:
- Sustained conduction recovery + LV recovery + symptom resolution → annual primary care follow-up only
- Persistent abnormality → continued cardiology / EP / ID specialist follow-up

Escalation triggers (move to higher acuity):
- Persistent AV block at 6 weeks → permanent pacer evaluation (rare)
- Persistent EF<40 at 3 months → cardiology long-term follow-up + chronic HFrEF management
- Recurrent palpitations / syncope → cards/EP urgent
- New tick-borne illness suspicion → ID

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] High-grade AV block (Mobitz II / CHB) with symptomatic bradycardia / hypotension refractory to atropine — temporary transvenous pacing needed; usually resolves within days-weeks of antibiotics
- [LIFE_THREATENING] Rare fulminant Lyme myocarditis variant with severe LV dysfunction + shock physiology — needs full CS support but recovery typically excellent with antibiotics if bridged
- [SEVERE] Lyme carditis presentation in patient WITHOUT recalled tick bite or erythema migrans rash (50-70% recall, 30-50% do not) — diagnosis relies on epidemiologic context + serology + clinical pattern

Citations

- IDSA / AAN / ACR Lyme Disease Clinical Practice Guidelines 2021 (Lantos PMID 33417672); CDC Lyme Disease Clinician Guidance + Modified Two-Tier Testing 2019; 2018 ACC/AHA/HRS Bradycardia Guideline (Kusumoto PMID 30412705); AHA Scientific Statement on Acute Myocarditis 2020 (Cooper); SCAI 2022 CS staging (Naidu PMID 35718438) [PMID:33417672](https://pubmed.ncbi.nlm.nih.gov/33417672/)
- Cited evidence (PMID 30412705) [PMID:30412705](https://pubmed.ncbi.nlm.nih.gov/30412705/)
- Cited evidence (PMID 23985496) [PMID:23985496](https://pubmed.ncbi.nlm.nih.gov/23985496/)
- Cited evidence (PMID 12767092) [PMID:12767092](https://pubmed.ncbi.nlm.nih.gov/12767092/)
- Cited evidence (PMID 35718438) [PMID:35718438](https://pubmed.ncbi.nlm.nih.gov/35718438/)

Last reconciled with current guidelines: 2026-05-15.
References
  • IDSA / AAN / ACR Lyme Disease Clinical Practice Guidelines 2021 (Lantos PMID 33417672); CDC Lyme Disease Clinician Guidance + Modified Two-Tier Testing 2019; 2018 ACC/AHA/HRS Bradycardia Guideline (Kusumoto PMID 30412705); AHA Scientific Statement on Acute Myocarditis 2020 (Cooper); SCAI 2022 CS staging (Naidu PMID 35718438) — PMID:33417672
  • Cited evidence (PMID 30412705) — PMID:30412705
  • Cited evidence (PMID 23985496) — PMID:23985496
  • Cited evidence (PMID 12767092) — PMID:12767092
  • Cited evidence (PMID 35718438) — PMID:35718438