What does borderline concentric hypertrophy on an echocardiogram (echo) mean?

Understanding Borderline Concentric Hypertrophy on Echocardiogram

Borderline concentric hypertrophy on an echocardiogram indicates an early or mild form of concentric left ventricular hypertrophy, characterized by a uniform increase in wall thickness with normal cavity size that has not yet reached the definitive threshold for diagnosis of pathological hypertrophy.

Definition and Characteristics

Concentric left ventricular hypertrophy (LVH) is characterized by:

• Uniformly increased wall thickness around the left ventricle
• Normal left ventricular cavity size
• Increased left ventricular mass
• Increased relative wall thickness (RWT >0.42) 1

The term "borderline" suggests measurements that are at the upper limits of normal or just crossing into abnormal territory, but not meeting full criteria for established concentric LVH.

Diagnostic Criteria

Concentric LVH is diagnosed echocardiographically using:

• Left ventricular mass index (LVMI): Values approaching but not definitively exceeding sex-specific cutoffs (110 g/m² for women and 134 g/m² for men) 2
• Relative wall thickness (RWT): Calculated as (posterior wall thickness × 2)/LV diastolic diameter 3
• Normal cavity size with wall thickness at upper limits of normal 3

Pathophysiology

Borderline concentric hypertrophy typically represents an early adaptive response to:

• Pressure overload conditions, most commonly hypertension
• Systemic pressure coupled with high peripheral resistance
• Aortic stenosis or other conditions causing increased afterload 3

At the cellular level, myocytes add sarcomeres in parallel (increasing cell width rather than length) in response to pressure overload conditions 1.

Clinical Significance and Implications

Risk Assessment

• Early indicator of target organ damage from hypertension
• Associated with increased cardiovascular risk even at borderline levels
• Predictor of progression to established LVH and potential heart failure 4

Functional Consequences

Borderline concentric LVH may be associated with:

• Early diastolic dysfunction
• Changes in longitudinal and radial myocardial function
• Potential atrial enlargement 3

Differential Diagnosis

It's important to distinguish borderline concentric LVH from:

1. True hypertrophic cardiomyopathy (HCM): Usually has asymmetric septal hypertrophy rather than uniform thickening 3

2. Athlete's heart: Usually presents with eccentric hypertrophy (increased mass with normal relative wall thickness) 3

3. Infiltrative disorders: May present with concentric LVH but often have additional echocardiographic features like "sparkling" myocardium in amyloidosis 3

Management Considerations

Management should focus on:

1. Identifying and treating underlying causes:

   • Aggressive blood pressure control if hypertensive
   • Evaluation for aortic stenosis or other valvular disease

2. Risk factor modification:

   • Lifestyle changes (weight reduction, sodium restriction, exercise)
   • Management of comorbidities (diabetes, dyslipidemia)

3. Follow-up monitoring:

   • Serial echocardiography to assess for progression
   • Evaluation of diastolic function parameters

Prognosis

Borderline concentric LVH carries intermediate risk:

• Higher risk than normal geometry but lower risk than established concentric LVH
• In the LIFE study, concentric LVH was associated with a hazard ratio of 2.71 for cardiovascular events 4
• With appropriate treatment, regression to normal geometry is possible 4

Common Pitfalls

1. Measurement errors: Ensure proper technique and multiple measurements to confirm borderline findings

2. Failure to index for body size: LV mass should be indexed to body surface area or height^2.7, especially in overweight/obese patients 3

3. Overlooking secondary causes: Consider conditions beyond hypertension, including aortic stenosis, infiltrative diseases, and genetic disorders 3

4. Misinterpreting normal variants: Some individuals may have constitutionally thicker walls without pathological significance

By understanding the significance of borderline concentric hypertrophy, clinicians can implement early interventions to prevent progression to established LVH and reduce cardiovascular risk.