The ECG shows characteristic ______ changes in V1-V3, with concave ST elevation and peaked T waves in early STEMI.

Hyperacute T-wave changes are early ECG findings in STEMI, occurring within minutes to hours of coronary occlusion. These changes include tall, peaked T waves with a broad base and symmetrical appearance, often seen before the classic ST-segment elevation becomes prominent.

ECG Changes in STEMI:

1. Hyperacute Phase (0-6 hours)
- Tall, peaked, symmetrical T waves
- Broad-based T waves
- Concave ST elevation
- Most prominent in V1-V3 leads

2. Key ECG Findings Timeline:
- Minutes 0-30: T wave peaking
- Hours 0-6: ST segment elevation
- Hours 6-12: Q wave development
- Hours 12-24: T wave inversion

3. Diagnostic Criteria:
- ST elevation ≥1mm in 2 contiguous leads
- New LBBB
- Reciprocal ST depression
- Posterior MI changes

4. Associated Features:
- J-point elevation
- Loss of R wave progression
- Mirror image changes
- Hyperacute T/QRS ratio >0.36

5. Lead-specific Changes:
- Anterior: V1-V4
- Lateral: I, aVL, V5-V6
- Inferior: II, III, aVF
- Posterior: V7-V9