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cardio.nstemi.hcm-microvascular.v1

NSTEMI in hypertrophic cardiomyopathy — microvascular ischemia + supply-demand mismatch

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12/12 authored

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

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Detailed

NSTEMI in HCM = microvascular ischemia + supply-demand mismatch (NOT atherosclerotic plaque rupture) driven by SAM-mediated LVOT obstruction + intramural arteriolar dysplasia + perfusion mismatch in hypertrophied septum; coronary angio typically unobstructed; treatment paradox vs atherosclerotic NSTEMI: AVOID NTG/ACEi/ARB/ARNI/DHP-CCB/aggressive diuretics/inotropes — TREAT the HCM physiology with BB or non-DHP CCB → disopyramide → mavacamten → septal reduction therapy

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HCM-microvascular paradigm framed before any drug ordered

Patient inputs (18)

Stress CMR with first-pass perfusion + late gadolinium enhancement (LGE) — gold-standard test for microvascular dysfunction in HCM per Petersen 2007 PMID 17502574; perfusion defects + mid-wall LGE in hypertrophied septum confirm HCM-microvascular MI substrate

HCM-microvascular NSTEMI spans wide age range; younger patients more likely to have genetic HCM (sarcomeric mutation); older patients may have HCM phenocopies (TTR amyloid, hypertensive HD); informs SCD risk + cascade screening

Pre-existing HCM diagnosis with documented LVOT gradient + LV thickness pattern (asymmetric septal vs apical vs concentric) + family history drives diagnostic confidence and immediate management; recent echo + CMR results critical

ESC HCM-RISK-SCD component + ACC/AHA 2024 SCD risk stratification; cascade family screening referral (50% autosomal dominant inheritance); informs ICD primary-prevention decision

Detect inadvertent vasodilators (ACEi, ARB, ARNI, NTG, nitrates, DHP-CCB amlodipine), inotropes (rare outpatient), or aggressive diuretics that may have precipitated LVOT obstruction crisis with supply-demand mismatch; need to stop or switch immediately

HypoK in stiff hypertrophied LV worsens VT/VF risk; also affects disopyramide proarrhythmia (QT prolongation); replete K to ≥4.0

Confirms NSTE-ACS pattern (T-wave inversion, dynamic ST depression, new BBB) + characterizes baseline HCM ECG (LVH voltage, lateral T-wave inversion, abnormal Q-waves); detects new AFib or VT/VF

Defines NSTEMI per 4th UDMI (PMID 30153967) rise/fall criteria; chronic mild troponin elevation common in HCM (microvascular dysfunction baseline) — ACUTE rise/fall above baseline drives NSTEMI label

eGFR for contrast load at cath / CMR gadolinium (avoid if eGFR <30); apixaban dosing if AF (2.5 mg BID per FDA criteria); disopyramide renal-adjustment; KDIGO 2021 race-free baseline

Baseline before any antiplatelet / AC; rules out anemia mimic for ischemia (anemia in HCM worsens supply-demand mismatch dramatically due to high O2 demand from hypertrophied myocardium)

Bedside or formal TTE — resting + provocable LVOT gradient (Valsalva, squat-to-stand), SAM, septal thickness, LVEF, mitral regurgitation severity — drives ALL drug decisions and management strategy

Coronary angiography typically UNOBSTRUCTED at epicardial level (HCM-microvascular substrate by definition); if focal lesion identified, dual aetiology (HCM + atherosclerotic NSTEMI) may apply; IVUS/OCT can detect microvascular dysfunction signs

Hypotension in HCM-microvascular NSTEMI = SAM-mediated LVOT obstruction crisis with supply-demand mismatch — treat with FLUIDS + phenylephrine + esmolol, NOT inotropes or vasodilators; SBP <90 triggers HCM-specific obstruction-crisis pathway

Tachycardia worsens LVOT gradient by shortening diastolic filling AND raises myocardial O2 demand → worsens supply-demand mismatch; HR target <80 with esmolol IV → metoprolol succinate / carvedilol PO; new AFib RVR requires emergent rate control or cardioversion

Pulmonary edema secondary to acute diastolic dysfunction + SAM-driven mitral regurgitation precipitating subendocardial ischemia; SpO2 <92% triggers cautious NIPPV (avoid pre-load drop)

Major SCD risk modifier in HCM (ESC 2014; ACC/AHA 2024); unexplained syncope shifts ICD decision toward primary prevention regardless of HCM-RISK-SCD score

AF stroke risk if AF detected — but in HCM, ANY AF = AC regardless of CHA2DS2-VASc score per ACC/AHA 2024 HCM Class I (atrial myopathy + LA enlargement drive elevated stroke risk); calculator used for documentation

HypoMg ↑ TdP risk on disopyramide (QT prolongation); maintain Mg ≥2.0

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

Severity triggers (6)

6 need judgement
  • informationallife_threateningsam_mediated_lvot_obstruction_crisis_with_microvascular_ischemia_worsened_by_inotropes
    HCM-microvascular NSTEMI patient given inadvertent inotrope (dobutamine, milrinone, epinephrine drip) for hypotension — paradoxically worsens SAM-mediated LVOT obstruction with cardiovascular collapse + worsens subendocardial ischemia
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningnew_afib_with_rvr_destabilizing_diastolic_filling_in_hcm_microvascular_nstemi
    New-onset AFib with rapid ventricular response in HCM-microvascular NSTEMI patient — loss of atrial kick + tachycardia → catastrophic drop in LV filling because stiff hypertrophied LV depends on atrial systole → worsens subendocardial ischemia
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereinadvertent_vasodilator_administered_in_hcm_microvascular_nstemi
    NTG, ACEi, ARB, ARNI, or DHP-CCB (amlodipine) administered to HCM-microvascular NSTEMI patient — drops afterload → worsens LVOT gradient → worsens subendocardial perfusion → worsens microvascular ischemia
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereseptal_reduction_therapy_decision_for_refractory_obstruction_with_microvascular_ischemia
    HCM-microvascular NSTEMI patient with persistent NYHA III-IV symptoms + LVOT gradient ≥50 mmHg at rest or with provocation despite maximally tolerated medical therapy (BB or CCB ± disopyramide ± mavacamten) — septal reduction therapy referral
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveremavacamten_lvef_drop_below_50pct_during_titration_in_microvascular_nstemi
    HCM-microvascular NSTEMI patient on mavacamten with REMS echo showing LVEF drop <50% during titration — REMS-mandated dose reduction or discontinuation
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereunexplained_syncope_or_nsvt_or_high_lge_burden_meeting_icd_criteria_in_hcm_microvascular_nstemi
    HCM-microvascular NSTEMI patient with unexplained syncope, NSVT on Holter, family history of SCD, LV thickness ≥30 mm, apical aneurysm on CMR, or high LGE burden (>15% LV mass) — primary-prevention ICD indication
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

HCM-microvascular NSTEMI regimen — overrides parent cardio.nstemi.core.v1 vasodilator + DAPT + statin defaults; uses BB or non-DHP CCB + ASA monotherapy + AC for AF (Class I regardless of CHA2DS2-VASc); chronic ladder: BB/CCB → disopyramide → mavacamten → septal reduction therapy — ACC/AHA 2024 HCM Guideline (Ommen) + ESC 2023 cardiomyopathies (Arbelo PMID 37622666) + EXPLORER-HCM (Olivotto PMID 32861276)
axis: nstemi_hcm_microvascular_phenotype
Selected axis "HCM-microvascular NSTEMI regimen — overrides parent cardio.nstemi.core.v1 vasodilator + DAPT + statin defaults; uses BB or non-DHP CCB + ASA monotherapy + AC for AF (Class I regardless of CHA2DS2-VASc); chronic ladder: BB/CCB → disopyramide → mavacamten → septal reduction therapy — ACC/AHA 2024 HCM Guideline (Ommen) + ESC 2023 cardiomyopathies (Arbelo PMID 37622666) + EXPLORER-HCM (Olivotto PMID 32861276)" by default fallback (first axis)
  • phenylephrine
    first line
    pure_alpha_1_agonist_vasopressor
    50-200 mcg IV bolus or 0.5-3 mcg/kg/min infusion titrate to MAP ≥65 • IV • bolus or continuous infusion
    triggers: hcm_microvascular_nstemi_with_hypotension, sam_mediated_lvot_obstruction_crisis
    Pure α-agonist increases afterload → reduces LVOT gradient by improving aortic ejection and abolishing SAM → relieves microvascular ischemia by improving subendocardial perfusion gradient; preferred over norepinephrine (β-component worsens obstruction) and ABSOLUTELY preferred over inotropes
    rxcui 8163
  • esmolol
    first line
    beta_1_selective_blocker_short_acting
    500 mcg/kg IV bolus then 50-300 mcg/kg/min infusion titrate to HR <80 • IV • continuous infusion
    triggers: hcm_microvascular_nstemi_with_tachycardia, sam_mediated_lvot_obstruction_crisis, new_afib_with_rvr_in_hcm
    Short-acting cardioselective β-blocker lengthens diastolic filling time + reduces inotropy → reduces LVOT gradient → improves subendocardial perfusion → relieves microvascular ischemia; titratable, off rapidly if hemodynamic compromise
    rxcui 203222
  • aspirin
    first line
    antiplatelet_cox1
    81 mg daily (no high-dose load if no atherosclerotic substrate identified) OR 162-325 mg load if concurrent atherosclerotic NSTEMI on imaging • PO • daily indefinitely
    triggers: hcm_microvascular_nstemi_confirmed
    ASA monotherapy reasonable in HCM-microvascular NSTEMI (no plaque rupture substrate); some authors continue indefinitely for general cardiovascular risk reduction; DAPT NOT routine (reserve P2Y12 only if concurrent atherosclerotic CAD on imaging) — different from atherosclerotic NSTEMI default
    rxcui 243670
  • metoprolol_succinate
    first line
    beta_blocker_beta1_selective
    25-50 mg PO daily titrate to maximally tolerated (target HR 60-80) • PO • daily
    triggers: chronic_hcm_obstructive_or_non_obstructive, transition_from_iv_esmolol
    ACC/AHA 2024 HCM Class I — first-line chronic β-blockade for symptomatic HCM; reduces inotropy + lengthens diastole → reduces LVOT gradient → improves microvascular perfusion
    rxcui 221124
  • carvedilol
    first line
    beta_blocker_nonselective_alpha1
    3.125 mg BID titrate to max tolerated (target HR 60-80) • PO • BID indefinitely
    triggers: chronic_hcm_with_concomitant_hfref_phenotype, metoprolol_intolerant
    ACC/AHA 2024 HCM Class I alternative; α1-blockade caution in obstructive HCM with very high gradient (vasodilator effect may worsen gradient — start low) — prefer metoprolol succinate as first choice in pure HOCM
    rxcui 20352
  • verapamil
    first line
    non_dhp_ccb_phenylalkylamine
    120 mg PO daily extended-release titrate to 480 mg/d max • PO • daily ER
    triggers: hcm_intolerant_to_beta_blocker, symptomatic_obstructive_or_non_obstructive_hcm_with_microvascular_substrate
    ACC/AHA 2024 HCM Class I alternative — non-DHP CCB; CAUTION in obstructive HCM with very high gradient or heart failure (vasodilator effect can worsen gradient — start low); improves diastolic relaxation and microvascular perfusion
    rxcui 11170
  • disopyramide
    second line
    class_ia_antiarrhythmic_negative_inotrope
    40-50 mg PO TID-QID extended-release titrate to 600-800 mg/d max; renal-adjusted • PO • TID-QID
    triggers: symptomatic_obstructive_hcm_refractory_to_bb_or_ccb, sam_with_lvot_gradient_above_50_mmhg_persistent
    ACC/AHA 2024 HCM Class IIa — negative inotrope reduces SAM and LVOT gradient → improves microvascular perfusion; QT prolongation + anticholinergic effects + proarrhythmic — monitor QT, K, Mg
    rxcui 3541
  • mavacamten
    second line
    cardiac_myosin_inhibitor
    5 mg PO daily start; titrate q4w per echo per REMS (max 15 mg/d) • PO • daily
    triggers: symptomatic_obstructive_hcm_nyha_ii_iii_refractory_to_bb_ccb_or_disopyramide, patient_avoids_septal_reduction_therapy
    ACC/AHA 2024 HCM Class IIa — first-in-class cardiac myosin inhibitor; EXPLORER-HCM PMID 32861276 (Olivotto Lancet 2020): 30% relative improvement in pVO2 + ~47% reduction in resting LVOT gradient; VALOR-HCM 2023: reduces septal reduction therapy referrals; REMS program — echo q4w during titration to detect LVEF drop <50%
    rxcui 2600867
  • apixaban
    comorbidity specific
    doac_factor_xa_direct
    5 mg PO BID (2.5 mg BID per FDA dose-reduction criteria) • PO • BID indefinite
    triggers: any_afib_in_hcm_regardless_of_cha2ds2vasc
    ACC/AHA 2024 HCM Class I — ANY AF in HCM = anticoagulate regardless of CHA2DS2-VASc score; DOAC preferred over warfarin; ARISTOTLE class evidence applies
    rxcui 1364430
  • rivaroxaban
    comorbidity specific
    doac_factor_xa_direct
    20 mg PO daily with food (15 mg if CrCl 15-50) • PO • daily indefinite
    triggers: any_afib_in_hcm_apixaban_alternative
    ACC/AHA 2024 HCM Class I — DOAC alternative for AF in HCM
    rxcui 1114195

outpatient playbook — drug actions (2)

  1. 1. continue chronic regimen at maximally tolerated dose
    rxcui 20352
    metoprolol succinate or verapamil + disopyramide if needed + mavacamten if eligible + ASA 81 daily • PO • as scheduled
    trigger: Chronic HCM-microvascular NSTEMI
    ACC/AHA 2024 HCM Class I/IIa
  2. 2. continue AC if AF
    rxcui 1364430
    apixaban 5 mg PO BID indefinite • PO • BID
    trigger: Any AF in HCM
    ACC/AHA 2024 HCM Class I

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Patient with known hypertrophic cardiomyopathy (resting or provocable LVOT gradient ≥30 mmHg, septal thickness ≥15 mm) presenting with ischemic chest pain + hsTn rise/fall + non-ST-elevation ECG — microvascular ischemia / supply-demand crisis on differential; NSTE-ACS workup angiogram shows unobstructed epicardial coronaries + bedside echo reveals asymmetric septal hypertrophy (≥15 mm) with SAM and dynamic LVOT gradient → HCM-microvascular NSTEMI substrate; Stress CMR shows first-pass perfusion defect + mid-wall LGE in hypertrophied septum + unobstructed epicardial coronaries — confirms HCM-microvascular MI substrate per Petersen 2007 PMID 17502574.

Objective

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

Assessment

**NSTEMI in hypertrophic cardiomyopathy — microvascular ischemia + supply-demand mismatch** (cardio.nstemi.hcm-microvascular.v1).
Phenotype framing: HCM-microvascular NSTEMI vs atherosclerotic NSTEMI (concurrent epicardial CAD on cath) vs vasospastic angina (Prinzmetal) vs broader MINOCA umbrella vs takotsubo overlap (apical ballooning + recent stressor) vs aortic dissection mimic vs HCM phenocopies (TTR amyloid, Fabry, Danon, hypertensive HD)
Scope: NSTEMI in HCM = microvascular ischemia + supply-demand mismatch (NOT atherosclerotic plaque rupture) driven by SAM-mediated LVOT obstruction + intramural arteriolar dysplasia + perfusion mismatch in hypertrophied septum; coronary angio typically unobstructed; treatment paradox vs atherosclerotic NSTEMI: AVOID NTG/ACEi/ARB/ARNI/DHP-CCB/aggressive diuretics/inotropes — TREAT the HCM physiology with BB or non-DHP CCB → disopyramide → mavacamten → septal reduction therapy

No severity triggers fired against current inputs.

Plan

Regimen axis: **HCM-microvascular NSTEMI regimen — overrides parent cardio.nstemi.core.v1 vasodilator + DAPT + statin defaults; uses BB or non-DHP CCB + ASA monotherapy + AC for AF (Class I regardless of CHA2DS2-VASc); chronic ladder: BB/CCB → disopyramide → mavacamten → septal reduction therapy — ACC/AHA 2024 HCM Guideline (Ommen) + ESC 2023 cardiomyopathies (Arbelo PMID 37622666) + EXPLORER-HCM (Olivotto PMID 32861276)**.
1. phenylephrine 50-200 mcg IV bolus or 0.5-3 mcg/kg/min infusion titrate to MAP ≥65 IV bolus or continuous infusion (pure_alpha_1_agonist_vasopressor, first line) — Pure α-agonist increases afterload → reduces LVOT gradient by improving aortic ejection and abolishing SAM → relieves microvascular ischemia by improving subendocardial perfusion gradient; preferred over norepinephrine (β-component worsens obstruction) and ABSOLUTELY preferred over inotropes
2. esmolol 500 mcg/kg IV bolus then 50-300 mcg/kg/min infusion titrate to HR <80 IV continuous infusion (beta_1_selective_blocker_short_acting, first line) — Short-acting cardioselective β-blocker lengthens diastolic filling time + reduces inotropy → reduces LVOT gradient → improves subendocardial perfusion → relieves microvascular ischemia; titratable, off rapidly if hemodynamic compromise
3. aspirin 81 mg daily (no high-dose load if no atherosclerotic substrate identified) OR 162-325 mg load if concurrent atherosclerotic NSTEMI on imaging PO daily indefinitely (antiplatelet_cox1, first line) — ASA monotherapy reasonable in HCM-microvascular NSTEMI (no plaque rupture substrate); some authors continue indefinitely for general cardiovascular risk reduction; DAPT NOT routine (reserve P2Y12 only if concurrent atherosclerotic CAD on imaging) — different from atherosclerotic NSTEMI default
4. metoprolol_succinate 25-50 mg PO daily titrate to maximally tolerated (target HR 60-80) PO daily (beta_blocker_beta1_selective, first line) — ACC/AHA 2024 HCM Class I — first-line chronic β-blockade for symptomatic HCM; reduces inotropy + lengthens diastole → reduces LVOT gradient → improves microvascular perfusion
5. carvedilol 3.125 mg BID titrate to max tolerated (target HR 60-80) PO BID indefinitely (beta_blocker_nonselective_alpha1, first line) — ACC/AHA 2024 HCM Class I alternative; α1-blockade caution in obstructive HCM with very high gradient (vasodilator effect may worsen gradient — start low) — prefer metoprolol succinate as first choice in pure HOCM
6. verapamil 120 mg PO daily extended-release titrate to 480 mg/d max PO daily ER (non_dhp_ccb_phenylalkylamine, first line) — ACC/AHA 2024 HCM Class I alternative — non-DHP CCB; CAUTION in obstructive HCM with very high gradient or heart failure (vasodilator effect can worsen gradient — start low); improves diastolic relaxation and microvascular perfusion
7. disopyramide 40-50 mg PO TID-QID extended-release titrate to 600-800 mg/d max; renal-adjusted PO TID-QID (class_ia_antiarrhythmic_negative_inotrope, second line) — ACC/AHA 2024 HCM Class IIa — negative inotrope reduces SAM and LVOT gradient → improves microvascular perfusion; QT prolongation + anticholinergic effects + proarrhythmic — monitor QT, K, Mg
8. mavacamten 5 mg PO daily start; titrate q4w per echo per REMS (max 15 mg/d) PO daily (cardiac_myosin_inhibitor, second line) — ACC/AHA 2024 HCM Class IIa — first-in-class cardiac myosin inhibitor; EXPLORER-HCM PMID 32861276 (Olivotto Lancet 2020): 30% relative improvement in pVO2 + ~47% reduction in resting LVOT gradient; VALOR-HCM 2023: reduces septal reduction therapy referrals; REMS program — echo q4w during titration to detect LVEF drop <50%
9. apixaban 5 mg PO BID (2.5 mg BID per FDA dose-reduction criteria) PO BID indefinite (doac_factor_xa_direct, comorbidity specific) — ACC/AHA 2024 HCM Class I — ANY AF in HCM = anticoagulate regardless of CHA2DS2-VASc score; DOAC preferred over warfarin; ARISTOTLE class evidence applies
10. rivaroxaban 20 mg PO daily with food (15 mg if CrCl 15-50) PO daily indefinite (doac_factor_xa_direct, comorbidity specific) — ACC/AHA 2024 HCM Class I — DOAC alternative for AF in HCM

Setting playbook (outpatient) — Long-term HCM specialist clinic surveillance: q3-6 mo visits; mavacamten REMS echo q12w maintenance; annual Holter for NSVT; stress CMR q3-5y for fibrosis progression; cascade family screening; ICD/septal reduction therapy reassessment if symptomatic progression; AC continuation for AF
11. continue chronic regimen at maximally tolerated dose metoprolol succinate or verapamil + disopyramide if needed + mavacamten if eligible + ASA 81 daily PO as scheduled — Chronic HCM-microvascular NSTEMI (ACC/AHA 2024 HCM Class I/IIa)
12. continue AC if AF apixaban 5 mg PO BID indefinite PO BID — Any AF in HCM (ACC/AHA 2024 HCM Class I)

Non-pharmacologic actions:
- Sports clearance reassessment annually
- Cascade family screening (continued for first-degree relatives until age 60 if no genetic mutation identified)
- ICD/septal reduction reassessment if symptomatic progression
- Pregnancy planning specialist referral if applicable (high-risk obstetric + HCM cardiology team)
- Cardiac rehab maintenance phase (modified intensity)

AVOID / contraindication checks:
- Absolute_contraindication_dobutamine_milrinone_epinephrine_in_hcm_obstruction (worsens SAM and LVOT gradient — never give inotropes for HCM hypotension; ACC/AHA 2024 HCM)
- Absolute_contraindication_nitroglycerin_acei_arb_arni_in_acute_hcm_obstruction (vasodilator drops afterload → worsens LVOT gradient + worsens microvascular ischemia)
- Caution_aggressive_diuresis_in_hcm (drops preload → worsens LVOT gradient; use small doses only if frank pulmonary edema)
- Caution_dhp_ccb_amlodipine_in_hcm_obstructive (vasodilator effect worsens gradient — use non DHP only)
- Dapt_not_routine_in_hcm_microvascular_nstemi_no_plaque_rupture (reserve P2Y12 only if concurrent atherosclerotic CAD on imaging)
- Lipid_lowering_only_if_concomitant_ascvd_in_hcm_microvascular_nstemi (no plaque rupture substrate; different from atherosclerotic NSTEMI)
- Disopyramide_qt_monitoring_required_with_k_and_mg_repletion (proarrhythmic if hypoK / hypoMg)
- Mavacamten_rems_echo_lvef_monitoring_q4w_during_titration_then_q12w_maintenance (LVEF drop <50% → dose reduction or discontinuation)
- Mavacamten_avoid_with_strong_cyp3a4_inhibitors_or_inducers (clarithromycin, ketoconazole, rifampin — drug interaction algorithm in REMS)
- Decision:any_af_in_hcm_class_i_anticoagulation_regardless_of_cha2ds2vasc (ACC/AHA 2024 HCM)
- Decision:septal_reduction_therapy_at_experienced_center_for_lvot_gradient_above_50_mmhg_nyha_iii_iv_refractory_to_medical_therapy (Class I)
- Decision:icd_for_primary_prevention_per_esc_2014_hcm_risk_score_5pct_5y_or_acc_aha_2024_modifiers (LGE, family history SCD, syncope, NSVT, apical aneurysm, LV thickness ≥30 mm)

Monitoring

Regimen monitoring:
- continuous ecg telemetry for af and vt vf surveillance (Class I)
- serial hstn q6h until peak then daily x 2 (4th UDMI)
- echo at admission then serial for lvot gradient and lv function recovery
- echo q4w during mavacamten titration per rems (FDA label)
- echo q12w maintenance on mavacamten (REMS)
- qt interval baseline then q3d during disopyramide titration then quarterly (FDA label)
- k and mg repletion to above 4.0 and above 2.0 (proarrhythmia prevention)
- cmr with lge at diagnosis then q3 5y for fibrosis progression (ACC/AHA 2024)
- holter 24 48h at baseline and q1 2y for nsvt scd modifier (ESC 2014; ACC/AHA 2024)
- cascade family screening q3 5y or at genetic test completion (ESC 2014; ACC/AHA 2024)

Setting (outpatient) monitoring:
- Echo q3-6 mo or q12w on mavacamten maintenance
- Holter q1-2y
- Stress CMR q3-5y
- Annual SCD risk reassessment

Follow-up plan: HCM specialist clinic within 1-2 weeks; cascade family genetic counseling + screening (50% autosomal dominant inheritance per ACC/AHA 2024); mavacamten REMS echo q4w during titration then q12w maintenance; ICD/septal reduction decision finalized per SCD criteria; AC continuation indefinite if AF; sports clearance shared decision; cardiac rehab if NYHA II-III (modified intensity — avoid heavy isometric exercise); long-term cardiology surveillance
- Close-out criterion: long-term plan + family screening + follow-up cadence finalized

Monitoring phase: Telemetry continuous first 48-72 h (arrhythmia surveillance + AF detection); serial echo for LV function recovery; serial hsTn to peak; BMP daily + Mg + K repletion; QT on disopyramide; if AFib AC therapeutic; serial Holter for NSVT (SCD modifier); echo q4w during mavacamten titration per REMS

Disposition

Current setting: outpatient — Long-term HCM specialist clinic surveillance: q3-6 mo visits; mavacamten REMS echo q12w maintenance; annual Holter for NSVT; stress CMR q3-5y for fibrosis progression; cascade family screening; ICD/septal reduction therapy reassessment if symptomatic progression; AC continuation for AF

Disposition criteria:
- Indefinite HCM specialist follow-up; lifelong AC if AF; ICD if SCD criteria met; mavacamten or septal reduction per individual response; cross-link to cardio.hcm.chronic.v1 for long-term outpatient management

Escalation triggers (move to higher acuity):
- Symptomatic progression → escalate medical therapy or septal reduction therapy
- New VT/VF or syncope → urgent EP / ICD evaluation
- New AF → STAT AC initiation regardless of CHA2DS2-VASc
- End-stage dilated phenotype (LVEF <50%) → switch to cardio.hfref.core.v1 for GDMT 4-pillar

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] HCM-microvascular NSTEMI patient given inadvertent inotrope (dobutamine, milrinone, epinephrine drip) for hypotension — paradoxically worsens SAM-mediated LVOT obstruction with cardiovascular collapse + worsens subendocardial ischemia
- [LIFE_THREATENING] New-onset AFib with rapid ventricular response in HCM-microvascular NSTEMI patient — loss of atrial kick + tachycardia → catastrophic drop in LV filling because stiff hypertrophied LV depends on atrial systole → worsens subendocardial ischemia
- [SEVERE] NTG, ACEi, ARB, ARNI, or DHP-CCB (amlodipine) administered to HCM-microvascular NSTEMI patient — drops afterload → worsens LVOT gradient → worsens subendocardial perfusion → worsens microvascular ischemia

Citations

- ACC/AHA 2024 HCM Guideline (Ommen) + ESC 2023 cardiomyopathies (Arbelo PMID 37622666) + ESC 2014 HCM (Elliott PMID 25173338) for SCD risk + 2025 ACC/AHA ACS Guideline (Rao) for parent ACS arc [PMID:37622666](https://pubmed.ncbi.nlm.nih.gov/37622666/)
- Cited evidence (PMID 25173338) [PMID:25173338](https://pubmed.ncbi.nlm.nih.gov/25173338/)
- Cited evidence (PMID 32861276) [PMID:32861276](https://pubmed.ncbi.nlm.nih.gov/32861276/)
- Cited evidence (PMID 37622670) [PMID:37622670](https://pubmed.ncbi.nlm.nih.gov/37622670/)
- Cited evidence (PMID 30153967) [PMID:30153967](https://pubmed.ncbi.nlm.nih.gov/30153967/)

Last reconciled with current guidelines: 2026-05-15.
References
  • ACC/AHA 2024 HCM Guideline (Ommen) + ESC 2023 cardiomyopathies (Arbelo PMID 37622666) + ESC 2014 HCM (Elliott PMID 25173338) for SCD risk + 2025 ACC/AHA ACS Guideline (Rao) for parent ACS arc — PMID:37622666
  • Cited evidence (PMID 25173338) — PMID:25173338
  • Cited evidence (PMID 32861276) — PMID:32861276
  • Cited evidence (PMID 37622670) — PMID:37622670
  • Cited evidence (PMID 30153967) — PMID:30153967