Causes of Left Ventricular Hypertrophy
Left ventricular hypertrophy (LVH) results from either physiologic adaptation (athletic training, pregnancy) or pathologic processes, with the most common pathologic causes being hypertension, genetic sarcomeric mutations (hypertrophic cardiomyopathy), infiltrative diseases (amyloidosis, sarcoidosis, Fabry disease), metabolic/storage disorders, and valvular heart disease.
Primary Classification Framework
LVH causes can be systematically categorized into:
1. Pressure/Volume Overload States
- Hypertension - the most common cause of LVH in adults, present in approximately 20-50% of hypertensive patients when assessed by echocardiography 1
- Aortic stenosis - valvular obstruction causing pressure overload
- Aortic regurgitation - volume overload leading to eccentric hypertrophy
- Coarctation of the aorta - creates afterload mismatch
2. Genetic/Sarcomeric Causes
Hypertrophic cardiomyopathy (HCM) represents the majority of genetic cases in adolescents and adults, caused by autosomal dominant mutations in genes encoding sarcomeric proteins 1. The most commonly affected genes include:
- MYBPC3 (myosin-binding protein C)
- MYH7 (β-myosin heavy chain)
- TNNT2 (cardiac troponin T)
- TNNI3 (cardiac troponin I)
- TPM1 (α-tropomyosin)
- MYL3 (myosin light chain 3)
Approximately 1,400 mutations across at least 8 genes have been identified 2.
3. Metabolic and Storage Disorders
Glycogen storage diseases:
- Pompe disease (acid maltase deficiency)
- Danon disease (LAMP2 mutations)
- PRKAG2 mutations (AMP-kinase disorders)
Lysosomal storage diseases:
- Fabry disease (α-galactosidase A deficiency) - particularly important to identify as enzyme replacement therapy is available 1
Mitochondrial diseases:
- MELAS (mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes)
- MERRF (myoclonic epilepsy with ragged red fibers)
- Other respiratory chain defects 1
4. Infiltrative Diseases
Cardiac amyloidosis - progressive infiltration causing biventricular wall thickening 1:
- AL (light chain) amyloidosis
- Hereditary ATTR (transthyretin-related)
- Wild-type ATTR (senile cardiac amyloidosis)
Other infiltrative conditions:
- Cardiac sarcoidosis
- Hemochromatosis
5. Malformation/RASopathy Syndromes
These involve mutations in the RAS/MAPK signaling pathway 1, 3:
- Noonan syndrome - most common, can present in adulthood
- LEOPARD syndrome
- Costello syndrome
- Cardiofaciocutaneous (CFC) syndrome
6. Neuromuscular Diseases
- Friedreich's ataxia - most common neuromuscular cause of LVH 1
- FHL-1 mutations (Four and a half LIM domain protein 1)
- Desmin gene mutations
- Nemaline myopathy
7. Endocrine Disorders
LVH typically resolves with treatment of the underlying condition 1:
- Acromegaly (growth hormone excess)
- Pheochromocytoma (catecholamine excess)
- Diabetes (transient hypertrophy in infants of diabetic mothers)
8. Drug-Induced LVH
Chronic use of specific medications 1:
- Anabolic steroids
- Tacrolimus (immunosuppressant)
- Hydroxychloroquine
- Corticosteroids
Important caveat: Drug-induced LVH rarely produces wall thickness ≥15 mm 1.
9. Physiologic (Non-Pathologic) LVH
- Athletic heart - adaptive response to intense training, typically with LV cavity enlargement and normal diastolic function 2, 3
- Pregnancy - transient adaptive hypertrophy
Critical Diagnostic Distinctions
When evaluating LVH, distinguish true HCM from phenocopies by considering 3:
Features favoring HCM over athlete's heart:
- LV cavity dimension <54 mm
- Abnormal diastolic function
- Unusual/asymmetric distribution of hypertrophy
- Family history of HCM or sudden cardiac death
- Presence of sarcomeric gene mutation
Features suggesting infiltrative/metabolic disease rather than HCM:
- Extracardiac manifestations (neuropathy, renal disease, skin findings)
- Biventricular hypertrophy
- Biatrial enlargement
- Thickened valves
- Specific CMR findings (late gadolinium enhancement patterns)
Common Pitfalls
Do not label systemic/metabolic diseases with LVH as "HCM" - these have different pathophysiology, natural history, and treatment 3, 4
In elderly patients with hypertension and LVH, consider coexistent HCM if wall thickness ≥25 mm or LVOT obstruction with systolic anterior motion is present 2
Modest LVH (13-15 mm) creates diagnostic uncertainty - requires integration of family history, genetic testing, ECG abnormalities, and imaging patterns 1
Isolated basal septal hypertrophy in elderly may represent age-related changes rather than pathologic HCM 1