## Distinguishing AMI from LVH on ECG ### Key ECG Features Comparison | Feature | AMI | LVH | |---------|-----|-----| | **ST segment** | Elevation (acute) or depression (subendocardial) | Usually normal or depressed (strain pattern) | | **T wave** | Inverted (acute/evolving) | Inverted in lateral leads (strain) | | **QRS voltage** | Normal or decreased | Increased (Sokolow-Lyon, Cornell criteria) | | **Reciprocal changes** | Present in transmural infarction | Absent | | **Q waves** | Pathological (>40 ms, >1/3 QRS height) | Absent or small | | **QT interval** | May be prolonged | Often prolonged (LVH-related) | | **Axis** | Variable | Often normal or left | **Key Point:** ST segment elevation with reciprocal ST depression is the hallmark of acute transmural MI and is virtually absent in LVH. LVH shows increased QRS voltage without acute ST-T changes. ### Why This Discriminates **High-Yield:** Reciprocal ST changes (ST elevation in one territory with simultaneous ST depression in the opposite territory) are pathognomonic for acute MI and indicate transmural myocardial injury. This finding is NOT seen in LVH, which is a chronic structural remodeling process without acute ischemia. **Clinical Pearl:** A patient with LVH may have ST depression and T wave inversion in lateral leads (strain pattern), but this is gradual and symmetric, lacking the acute ST elevation and reciprocal depression seen in MI. ### Mechanism 1. **AMI:** Transmural ischemia → depolarization abnormality → ST elevation at injury site + reciprocal ST depression in opposite wall 2. **LVH:** Chronic pressure overload → concentric hypertrophy → increased QRS voltage + secondary repolarization changes (strain) without acute ST elevation 
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