Ventricular Hypertrophy and Deep T-Wave Inversions on ECG: Electrophysiological Mechanisms
Ventricular hypertrophy causes deep T-wave inversions on ECG primarily due to altered repolarization characteristics of ventricular myocytes, particularly on the endocardial surface, creating abnormal transmural voltage gradients during repolarization. 1
Electrophysiological Basis
Primary Repolarization Abnormalities
- Ventricular hypertrophy causes changes in the shape and duration of ventricular action potentials, particularly in endocardial cells 1
- These changes create abnormal transmural voltage gradients during repolarization that manifest as T-wave inversions
- In hypertrophied hearts, the normal sequence of repolarization (epicardium to endocardium) may be reversed, leading to T-wave inversions 2
Combined Primary and Secondary Mechanisms
- Ventricular hypertrophy produces both primary and secondary repolarization abnormalities:
- Primary: Direct changes to cellular repolarization characteristics
- Secondary: Changes related to altered depolarization sequence (QRS changes) 1
- The magnitude of T-wave changes correlates with the degree of hypertrophy, particularly in the apical region 3
Clinical Patterns and Significance
Left Ventricular Hypertrophy (LVH)
- LVH with repolarization abnormalities (T-wave inversions) carries more than double the cardiovascular risk compared to hypertension alone 4
- T-wave inversions in LVH are associated with:
Specific Patterns
- In hypertrophic cardiomyopathy (HCM), deep T-wave inversions (>1.2 mV) in left precordial leads often indicate asymmetrical apical hypertrophy 3
- The depth of T-wave inversion correlates with the ratio of apical to mid-wall thickness 3
- T-wave inversions ≥1 mm may indicate various cardiomyopathies including HCM, arrhythmogenic right ventricular cardiomyopathy, and left ventricular non-compaction 5
Right Ventricular Hypertrophy (RVH)
- RVH patterns often show ST depression and T-wave inversion in right precordial leads 1
- These ST-T abnormalities are better referred to as "secondary ST-T abnormality" rather than "strain" 1
- RVH may be classified based on ECG patterns suggesting either volume overload (incomplete RBBB pattern) or pressure overload (tall R waves in right precordial leads) 1
Clinical Implications and Management
Diagnostic Approach
- T-wave inversions >2 mm with increased QRS voltage should prompt evaluation for underlying structural heart disease 1
- Non-specific ST-segment and T-wave changes are defined as ST-segment deviation <0.5 mm and T-wave inversion ≤2 mm 5
- Echocardiography is recommended as first-line imaging to assess ventricular hypertrophy and function 5
Risk Stratification
- Deep T-wave inversions (>0.5 mV) in leads V2-V4 represent high-risk features 5
- ECG-LVH with repolarization abnormalities identifies hypertensive patients with compromised coronary circulation and myocardial damage 4
- T-wave pseudonormalization during stress testing in HCM may indicate myocardial ischemia, sometimes before significant ST-segment changes appear 6
Important Caveats
- T-wave inversions may be the only ECG manifestation of myocardial ischemia in patients with ventricular hypertrophy 6
- The correlation between ECG criteria for hypertrophy and actual anatomic hypertrophy is modest; ECG abnormalities reflect both hypertrophy and myocardial damage 4
- A completely normal ECG does not exclude significant cardiac pathology; 1-6% of patients with normal ECGs may have NSTEMI or unstable angina 5
- T-wave inversions in athletes require careful evaluation to distinguish physiological adaptations from pathological conditions 1
Understanding these electrophysiological mechanisms helps clinicians appropriately interpret T-wave inversions in the context of ventricular hypertrophy and guides further diagnostic and therapeutic decisions to reduce morbidity and mortality.