Which ECG finding best distinguishes acute myocardial infarction (AMI) from left ventricular hypertrophy (LVH)?

Question

Accepted Answer

D. ST-segment elevation with reciprocal ST-segment depression. ## Distinguishing AMI from LVH on ECG

### Key Diagnostic Features

**Key Point:** ST-segment elevation with reciprocal ST-segment depression is pathognomonic for acute transmural myocardial infarction and is NOT seen in LVH, which is a chronic structural change.

### Comparison Table

| Feature | Acute MI | LVH |
| --- | --- | --- |
| **ST-segment elevation** | Present (acute transmural injury) | Absent |
| **Reciprocal ST depression** | Yes (in non-infarcted territory) | No |
| **QRS voltage** | May be normal or low | Increased (Sokolow-Lyon, Cornell criteria) |
| **T-wave changes** | Symmetrical inversion (acute phase) | Asymmetrical inversion (strain pattern) |
| **Onset** | Acute (hours) | Gradual (months to years) |
| **Evolutionary pattern** | Dynamic (ST→T changes over days) | Static |

### Why ST-Elevation is the Best Discriminator

**High-Yield:** ST-segment elevation indicates acute transmural myocardial injury (necrosis of the full thickness of myocardium). This is an acute, dynamic process that does NOT occur in LVH, which is purely a chronic hypertrophic response to pressure overload.

**Clinical Pearl:** The presence of reciprocal ST-segment depression (in leads opposite the infarct territory) further strengthens the diagnosis of AMI and is virtually never seen in LVH alone.

### Why Other Findings Are Shared or Non-Specific

- **Increased QRS voltage:** Both AMI and LVH can show increased voltage, especially if the infarct is small or if LVH is severe. This is NOT discriminatory.
- **T-wave inversion:** Can occur in both conditions. In AMI, it is symmetrical and evolves dynamically; in LVH, it is asymmetrical (strain pattern) and static. However, T-wave inversion alone does not reliably distinguish them.
- **Left axis deviation:** More common in LVH but can occur in inferior MI or other conditions. Not specific enough to distinguish AMI from LVH.

[cite:Harrison 21e Ch 297]

![ECG Interpretation Basics diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3436.webp)

Answer

A. Increased QRS voltage in precordial leads

Answer

B. Left axis deviation

Answer

C. T-wave inversion in lateral leads

Which ECG finding best distinguishes acute myocardial infarction (AMI) from left ventricular hypertrophy (LVH)?

Explanation

Distinguishing AMI from LVH on ECG

Key Diagnostic Features

Comparison Table

Why ST-Elevation is the Best Discriminator

Why Other Findings Are Shared or Non-Specific

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Feature	Acute MI	LVH
ST-segment elevation	Present (acute transmural injury)	Absent
Reciprocal ST depression	Yes (in non-infarcted territory)	No
QRS voltage	May be normal or low	Increased (Sokolow-Lyon, Cornell criteria)
T-wave changes	Symmetrical inversion (acute phase)	Asymmetrical inversion (strain pattern)
Onset	Acute (hours)	Gradual (months to years)
Evolutionary pattern	Dynamic (ST→T changes over days)	Static