Cardiovascular · Year 1 · from Cardiovascular
Case 1: Acute Anterior STEMI
Patient Presentation
Demographics: 62-year-old male
Chief Complaint: Severe chest pain and shortness of breath for 45 minutes
History of Present Illness: A 62-year-old male with history of diabetes, hyperlipidemia, and 40 pack-year smoking history presents with severe substernal chest pressure radiating to his left arm. The pain began suddenly 45 minutes ago while eating breakfast. He describes it as "an elephant sitting on my chest." He is also experiencing shortness of breath, nausea, and diaphoresis. He took aspirin at home before calling 911.
Physical Examination:
- Vital Signs: BP 145/95 mmHg, HR 105 bpm, RR 24/min, SpO2 93% on room air
- General: Diaphoretic, pale, anxious, clutching chest
- Cardiovascular: Tachycardic, regular rhythm, S4 gallop, no murmurs
- Lungs: Bibasilar crackles
- Extremities: Cool, slightly mottled
Workup
- ECG Findings:
- ST-segment elevation in V1-V4 (≥2 mm) - anterior leads
- ST-segment elevation in I, aVL - high lateral leads
- Reciprocal ST depression in II, III, aVF
- Q waves beginning to form in V1-V3
- Hyperacute T waves in V2-V4
- ECG Interpretation:
- Rate: 105 bpm
- Rhythm: Sinus tachycardia
- Axis: Normal (approximately +30°)
- Intervals: PR 160 ms, QRS 100 ms, QTc 440 ms
- Conclusion: Acute anterolateral STEMI
- Labs: Troponin I: 12.5 ng/mL (markedly elevated), BNP: 450 pg/mL
Diagnosis
Acute anterolateral ST-elevation myocardial infarction (STEMI) - likely LAD occlusion
ECG Correlation: The ECG leads reflect different anatomical regions:
- Anterior leads (V1-V4): Left anterior descending artery territory
- Lateral leads (I, aVL, V5-V6): Circumflex or diagonal branches
- Inferior leads (II, III, aVF): Right coronary artery territory
ST elevation in V1-V4 with lateral involvement indicates proximal LAD occlusion. Reciprocal changes (ST depression) in inferior leads support acute STEMI. The ST-segment represents the plateau phase (phase 2) of the action potential; ischemia causes abnormal repolarization creating the current of injury seen as ST elevation.
Treatment
- Immediate activation of cardiac catheterization lab
- DAPT: Aspirin 325 mg (already given) + P2Y12 inhibitor (ticagrelor 180 mg or prasugrel 60 mg)
- Anticoagulation: Heparin bolus
- Primary PCI within 90 minutes (door-to-balloon time)
- Oxygen for SpO2 <90%
- Pain management (morphine if needed)
- Beta-blocker (if no signs of heart failure or cardiogenic shock)
Clinical Image
Image Description: 12-lead ECG demonstrating acute anterior STEMI with marked ST-segment elevation in precordial leads V1-V4. Note the convex (tombstone) ST elevation, hyperacute T waves, and reciprocal ST depression in inferior leads.
Source: Wikimedia Commons - Acute anterior myocardial infarction ECG License: CC BY-SA 4.0 URL: https://commons.wikimedia.org/wiki/File:AMI_anterior_V1-V4.png