Step 1 — Select Clinical Scenario
What is the clinical question?
Select the pathway that best matches the current clinical situation
🔍 Suspected / New HCM
New presentation with symptoms, abnormal ECG, murmur, or family history — needs diagnostic evaluation and genetic workup
⚕️ Established HCM — Management
Known HCM diagnosis — guide ICD decision, symptom management, and heart failure therapy (Figures 3, 4 & 5)
👨👩👧 Family Screening
First-degree relative of HCM patient — determine when to start screening and how often to repeat ECG and echo (Table 2)
⚡ SCD Risk Assessment
Evaluate all sudden cardiac death risk factors to guide ICD decision-making in adults and children (Table 3 + Figure 3)
Step 2 — Phenotype Assessment (Figure 1)
What does diagnostic testing show?
After ECG, echocardiography, and/or CMR imaging — select phenotype status
Phenotype Positive
LV wall thickness ≥15 mm (or ≥13 mm with family history) — HCM diagnosis established on imaging
Phenotype Negative
No morphologic HCM on imaging — evaluate for genetic carrier status based on family history
Is there a known P/LP variant in the family?
Yes — known P/LP variant in family
No — no known variant / family not tested
Does the patient carry the family variant?
Yes — variant positive
Unknown / not yet tested
No — variant negative
Step 2 — Prior Cardiac Arrest (Figure 3)
Has the patient had a prior event?
Sudden cardiac death, ventricular fibrillation, or sustained ventricular tachycardia
Yes — Prior SCD / VF / Sustained VT
Documented cardiac arrest or resuscitation, or hemodynamically significant sustained VT
No prior event
No prior SCD, VF, or sustained VT — proceed to risk factor and symptom assessment
Step 3 — ICD Risk Factors + Physiology (Figures 3, 4 & 5)
Select all present risk factors and physiology
Check all applicable — determines ICD class and management pathway
SCD Risk Factors (Table 3)
Obstructive physiology? (LVOTO gradient ≥30 mmHg at rest or provocation)
Yes — obstructive HCM
No — non-obstructive HCM
Symptoms present (dyspnoea, chest pain, presyncope)?
Yes — symptomatic
No — asymptomatic
Left ventricular ejection fraction (LVEF)
LBBB present with LVEF <50%?
Yes — LVEF <50% + LBBB
No LBBB
Step 2 — Relative Profile (Table 2)
Age group of the first-degree relative
Select the category that matches the relative — determines initiation and frequency of screening
Child / Adolescent — Genotype-positive family
Family has identified P/LP variant, OR early-onset HCM disease in the family
Child / Adolescent — Other HCM family
HCM diagnosed in family but no identified P/LP variant and not early-onset
Adult (≥18 years)
Adult first-degree relative of any HCM patient, regardless of variant status
Step 2 — SCD Risk Checklist (Table 3 + Figure 3)
Check all risk factors present
2024 AHA/ACC Table 3 — applies to adults and children with confirmed HCM
NSVT burden detail
Infrequent, short, slow NSVT
Frequent (≥3 runs), long (≥10 beats) or fast (≥200 bpm)