What is Left Ventricular Hypertrophy?
Left ventricular hypertrophy (LVH) is an abnormal increase in left ventricular wall thickness, typically defined as maximal LV wall thickness ≥15 mm in adults (with 13-14 mm considered borderline), representing either a pathological response to pressure/volume overload or a primary genetic condition. 1
Definition and Diagnostic Criteria
LVH represents an increase in left ventricular mass that can be measured as increased wall thickness, which may be diffuse or segmental in distribution. 1 The condition develops when the heart muscle thickens beyond normal limits, defined as >2 standard deviations above the mean for age, sex, or body size in children. 1
Measurement Thresholds
The most widely accepted diagnostic thresholds for LVH by echocardiography are: 2
- Men: LV mass index >125 g/m² (or >115 g/m² by some criteria)
- Women: LV mass index >110 g/m² (or >95 g/m² by some criteria)
- Wall thickness: Septal or posterior wall thickness >1.0 cm in women or >1.1 cm in men is considered abnormal 2
Pathophysiology and Types
Physiological vs. Pathological LVH
LVH can be either physiological (adaptive) or pathological (maladaptive). 2
Physiological LVH occurs in: 2
- Athletic training (athlete's heart)
- Pregnancy
- Normal developmental growth
Pathological LVH develops in response to: 2, 1
- Pressure overload: Hypertension, aortic stenosis
- Volume overload: Valvular regurgitation
- Primary genetic mutations: Hypertrophic cardiomyopathy (HCM)
- Infiltrative/storage diseases: Amyloidosis, Fabry disease
- Myocardial injury
Geometric Patterns
Concentric LVH is characterized by increased wall thickness with normal or decreased LV cavity size, typically seen in chronic pressure overload states like hypertension. 2 This pattern shows increased left ventricular mass with a wall-to-radius ratio ≥0.42. 2
Eccentric LVH features increased LV mass with increased cavity size and a wall-to-radius ratio <0.42, commonly seen in volume overload conditions. 2
Concentric remodeling involves a normal LV mass but increased wall-to-radius ratio ≥0.42, representing an intermediate stage that also predicts increased cardiovascular risk. 2
Asymmetric LVH shows uneven distribution of hypertrophy, most commonly seen in hypertrophic cardiomyopathy. 1
Clinical Significance and Prognosis
LVH is an independent predictor of cardiovascular mortality, stroke, heart failure, coronary heart disease, and sudden cardiac death, regardless of blood pressure levels. 2, 3
The prognostic impact is substantial: 2
- For every 50 g/m² increase in left ventricular mass index, the relative risk of death increases by 1.73 (95% CI 1.19-2.52) in predominantly white populations
- In African-Americans, LVH confers a hazard ratio of 1.88 in men and 1.92 in women for cardiovascular events
- In American Indians, LVH increases cardiovascular mortality 7-fold and all-cause mortality 4-fold
Concentric hypertrophy consistently demonstrates the highest cardiovascular risk among all geometric patterns. 2
Mechanisms of Increased Risk
The pathophysiological mechanisms underlying increased mortality in LVH include: 2
- Decreased coronary flow reserve
- Greater susceptibility to ischemic injury
- Increased risk of arrhythmias (including atrial fibrillation) 2
- Diastolic dysfunction, which can occur even without systolic impairment 2
Diagnostic Approach
Electrocardiography
ECG is less sensitive than echocardiography for detecting LVH, identifying only about 5% of hypertensive patients with LVH compared to 50% detected by echocardiography. 4 However, when present, electrocardiographic LVH with repolarization abnormalities strongly predicts subsequent cardiovascular events. 2
Common ECG criteria include: 2
- Sokolow-Lyon voltage criteria (SV1 + RV5-6 ≥38 mm)
- Cornell voltage QRS duration product (>2440 mm·ms)
Echocardiography
Two-dimensional echocardiography is the first-line imaging modality for LVH diagnosis, providing accurate assessment of LV wall thickness, mass, and geometric patterns. 2, 1, 5 It allows comprehensive evaluation of both systolic and diastolic function. 5
The recommended measurement approach uses: 2
- Interventricular septum thickness
- Left ventricular posterior wall thickness
- End-diastolic diameter
- Calculation of LV mass using validated formulae
Advanced Imaging
Cardiovascular magnetic resonance (CMR) provides the most accurate measurements of LV wall thickness and mass, and is particularly valuable when echocardiography is inconclusive or when tissue characterization is needed. 1, 5 CMR can identify specific patterns of late gadolinium enhancement that help differentiate causes of LVH, such as distinguishing hypertrophic cardiomyopathy from cardiac amyloidosis. 5
Bone tracer scintigraphy is included in the diagnostic algorithm specifically for cardiac amyloidosis. 5
Chest Radiography
A cardiothoracic ratio >0.49 on chest X-ray predicts LVH with 93.3% sensitivity and 82.7% specificity, justifying echocardiographic evaluation in patients with hypertension or cardiovascular risk factors. 6
Prevalence
The estimated prevalence of LVH in the general population is approximately 0.2% (1 in 500 individuals). 1 However, this varies significantly based on the population studied and diagnostic criteria used, with much higher prevalence in hypertensive populations. 4
Common Pitfalls
A critical pitfall is using the term "cardiac hypertrophy" when referring to the whole heart, as hypertrophy technically refers to individual cardiac myocytes. 2 The more accurate term for whole-heart changes is "myocardial remodeling," which encompasses hypertrophy of cardiac myocytes and hyperplasia of non-myocyte components. 2
Another important consideration is that LVH measurement methodology and cut points vary widely among studies, with 19 different criteria identified in one meta-analysis. 2 The American Society of Echocardiography (ASE) methodology with sex-specific cut points is recommended for standardization. 2
Race-specific considerations are emerging, as athletic hypertrophy in African/Afro-Caribbean individuals may be greater than in whites, suggesting that pathological LVH definitions may need to be race-specific as well as sex-specific. 2