What is LV Mass Index?
The Left Ventricular Mass Index (LVMI) is the mass of the left ventricle normalized to body surface area (BSA). It is the primary echocardiographic criterion for diagnosing left ventricular hypertrophy (LVH) — an increase in the mass of the heart's main pumping chamber.
LVH is an independent predictor of adverse cardiovascular outcomes, including heart failure, stroke, arrhythmias, and sudden cardiac death. Indexing the LV mass to BSA helps account for differences in body size and allows meaningful comparisons across patients.
Formulas
The American Society of Echocardiography (ASE) recommends the Devereux formula (also called the cube formula or Penn convention) for estimating LV mass from M-mode echocardiography:
Body Surface Area is calculated using the Du Bois formula:
The LV Mass Index is then:
Relative Wall Thickness (RWT) is used alongside LVMI to classify LV geometry:
LVMI Categories
| Category | Women (g/m²) | Men (g/m²) |
|---|---|---|
| Normal | 43 – 95 | 49 – 115 |
| Mildly Abnormal | 96 – 108 | 116 – 131 |
| Moderately Abnormal | 109 – 121 | 132 – 148 |
| Severely Abnormal | ≥ 122 | ≥ 149 |
Heart Anatomy Diagram
LV Geometry Patterns
The combination of LVMI and Relative Wall Thickness (RWT) defines four distinct patterns of LV geometry, each with different clinical implications:
| Geometry | LVMI | RWT | Clinical Significance |
|---|---|---|---|
| Normal Geometry | Normal | ≤ 0.42 | No structural abnormality |
| Concentric Remodeling | Normal | > 0.42 | Pressure overload adaptation; increased CV risk |
| Eccentric Hypertrophy | Increased | ≤ 0.42 | Volume overload (e.g., aortic or mitral regurgitation) |
| Concentric Hypertrophy | Increased | > 0.42 | Pressure overload (e.g., hypertension, aortic stenosis); highest CV risk |
Causes of Left Ventricular Hypertrophy
LVH develops as the heart adapts to chronic pressure or volume overload:
- Hypertension: The most common cause; chronic pressure overload leads to concentric hypertrophy
- Aortic valve disease: Aortic stenosis (pressure overload) or regurgitation (volume overload)
- Hypertrophic cardiomyopathy (HCM): Genetic condition causing asymmetric septal hypertrophy
- Athletic heart: Physiological adaptation in endurance athletes; typically mild and reversible
- Obesity: Increases blood volume and cardiac output
- Coarctation of the aorta: Congenital narrowing causing upper body hypertension
- Chronic kidney disease: Volume overload, anemia, and hypertension contribute
Echocardiography
Echocardiography is the primary non-invasive imaging modality for assessing LV mass. Two main approaches are used:
- M-mode (Motion mode): Uses a single ultrasound beam to measure wall thicknesses and cavity dimensions. This is the method used in the Devereux formula. It is fast and reproducible but assumes symmetric geometry.
- 2D/3D echocardiography: Provides more accurate LV mass estimation, especially in asymmetric hypertrophy. The biplane Simpson method or real-time 3D imaging can be used.
Cardiac MRI is considered the gold standard for LV mass measurement but is more expensive and less widely available than echocardiography.
Worked Example
Given: LVEDD = 4.7 cm, IVSd = 0.9 cm, PWd = 0.9 cm, Height = 170 cm, Weight = 70 kg, Male
For a male, an LVMI of 78.8 g/m² falls within the normal range (49–115 g/m²). RWT = (2 × 0.9) / 4.7 = 0.38, which is ≤ 0.42, indicating normal geometry.
Frequently Asked Questions
Why is LVMI indexed to BSA?
Larger people naturally have larger hearts. Indexing LV mass to BSA removes the effect of body size, allowing clinicians to determine if the LV mass is truly increased (pathological hypertrophy) rather than simply proportional to a larger body. Some experts prefer indexing to height raised to the power of 2.7 (height2.7) to avoid underestimating LVH in obese patients.
Can LVH be reversed?
Yes, in many cases. Treating the underlying cause — particularly blood pressure control with antihypertensive medications — can lead to significant regression of LVH. ACE inhibitors, ARBs, and calcium channel blockers have been shown to be particularly effective. Weight loss and exercise also contribute to LVH regression.
What is the difference between physiological and pathological LVH?
Physiological (athlete's heart) LVH is a normal adaptation to regular exercise, characterized by mild symmetric hypertrophy with normal or supranormal systolic function and normal diastolic function. Pathological LVH is caused by disease (hypertension, valve disease, etc.) and is associated with fibrosis, diastolic dysfunction, and increased cardiovascular risk.
How accurate is M-mode for LV mass?
M-mode echocardiography provides reproducible measurements but has limitations. It assumes a symmetric, ellipsoid LV cavity and may overestimate mass in patients with asymmetric hypertrophy or regional wall motion abnormalities. When accuracy is critical, 3D echocardiography or cardiac MRI is preferred.