What is the cutoff for interventricular septum (IVS) and posterior wall (PW) thickness to diagnose concentric left ventricular hypertrophy (LVH)?

Cutoff Values for IVS and PW Thickness in Concentric LVH

For diagnosing concentric left ventricular hypertrophy, interventricular septum (IVS) and posterior wall (PW) thickness values exceeding 0.9 cm in women or 1.0 cm in men are considered abnormal, but the diagnosis requires calculating LV mass indexed to body surface area (>95 g/m² in women, >115 g/m² in men) combined with a relative wall thickness (RWT) ≥0.42. 1, 2

Normal Wall Thickness Reference Values

The ASE/EACVI guidelines establish clear upper limits of normal for wall thickness measurements:

• Women: IVS and PW thickness 0.6-0.9 cm 1, 2
• Men: IVS and PW thickness 0.6-1.0 cm 1, 2

These measurements should be obtained from the parasternal long-axis view at end-diastole, at the level of the mitral valve leaflet tips, using 2D-guided M-mode or direct 2D measurement at the tissue-blood interface. 1, 2

Defining Concentric LVH: The Critical RWT Calculation

Wall thickness alone is insufficient for diagnosing concentric LVH. You must calculate relative wall thickness (RWT) using the formula: RWT = (2 × PW thickness) / LV internal diameter at end-diastole. 1, 2

• Concentric LVH: RWT ≥0.42 with increased LV mass 1, 2
• Eccentric LVH: RWT <0.42 with increased LV mass 1, 2
• Concentric remodeling: RWT ≥0.42 with normal LV mass 1

Normal RWT ranges are 0.22-0.42 in women and 0.24-0.42 in men. 1, 2

LV Mass Calculation is Essential

The diagnosis of LVH should be based on calculated LV mass indexed to BSA, not wall thickness measurements alone. 1, 2 This is a critical distinction because:

• Wall thickness can be normal or only mildly increased even when LV mass is significantly elevated 3
• LV mass calculation is 78% sensitive for detecting LVH compared to only 48% sensitivity using wall thickness criteria alone 3

The recommended formula is: LVM = 0.8 × {1.04[(LVIDd + PW + IVSd)³ - (LVIDd)³]} + 0.6 g 1, 2

Upper limits of normal for indexed LV mass:

• Women: >95 g/m² (linear method) or >88 g/m² (2D method) 1, 2
• Men: >115 g/m² (linear method) or >102 g/m² (2D method) 1, 2

Important Clinical Caveats

Beware of asymmetric septal hypertrophy mimicking concentric LVH. A septal/posterior wall ratio ≥1.3 occurs in 39% of patients with concentric hypertrophy from hypertension or valvular disease, not just in hypertrophic cardiomyopathy. 4 However, ratios ≥1.5 are more specific for genetically determined asymmetric septal hypertrophy. 4

In the context of hypertrophic cardiomyopathy (HCM), different thresholds apply:

• Adults: Wall thickness ≥15 mm anywhere in the LV establishes HCM diagnosis 1
• Borderline cases: 13-14 mm may be diagnostic with family history or positive genetic testing 1
• First-degree relatives: ≥13 mm is diagnostic 1

Technical measurement considerations:

• Use 2D-guided measurements at the actual tissue-blood interface rather than leading-edge convention 1, 2
• Ensure M-mode cursor is perpendicular to the LV long axis 1, 2
• In upper septal hypertrophy, linear methods overestimate LV mass while area-length methods underestimate it 1