Guideline-Based HCM Assessment

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Hypertrophic Obstructive Cardiomyopathy

Comprehensive echo protocolSections for HOCM assessment — morphology, SAM grading, LVOT gradients, goal-directed Valsalva provocation, MR evaluation, and structured reporting.

Protocol Progress0/31 items

Maximal wall thickness (MWT)CRITICAL

Measure at end-diastole in the thickest segment. HOCM diagnosis: MWT ≥15 mm (or ≥13 mm with family history/genotype). Measure in PLAX and PSAX at multiple levels.

Normal: ≤11 mm (men), ≤10 mm (women)

Distribution of hypertrophy

Classify pattern: asymmetric septal hypertrophy (ASH) — most common; apical HCM — spade-shaped cavity, apical wall ≥15 mm; concentric HCM; mid-ventricular obstruction; reverse curvature (sigmoid) septum.

ASH: septal-to-posterior wall ratio ≥1.3

Basal septal thickness

Measure IVS thickness at basal level in PLAX. Sigmoid septum (age-related) vs. true HCM: sigmoid septum has localized basal bulge with normal MWT elsewhere.

Basal IVS >15 mm + sigmoid morphology = consider HCM

LV cavity size

HOCM often has small, hyperdynamic LV. Measure LVEDD and LVESD in PLAX M-mode or 2D. End-stage HCM: dilated LV with EF <50% — poor prognosis.

LVEDD normal: 42–58 mm (men), 38–52 mm (women)

LV systolic function (EF)CRITICAL

Biplane Simpson's method from A4C and A2C. HOCM typically hyperdynamic (EF >65%). EF <50% = burned-out/end-stage HCM — high SCD risk.

Normal EF: 52–72% (men), 54–74% (women)

Apical HCM screeningCRITICAL

Use A4C with contrast if apical wall not clearly seen. Apical HCM: apical wall ≥15 mm, spade-shaped cavity, apical aneurysm possible. Do NOT miss on standard imaging.

Contrast echo for apical HCM if unenhanced image suboptimal

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