Cardiovascular · Year 1 · from Cardiovascular

Case 2: Acute STEMI - Complete Coronary Occlusion

Patient Presentation

Demographics: 55-year-old male

Chief Complaint: Crushing chest pain for 90 minutes

History of Present Illness: A 55-year-old male with history of smoking (30 pack-years) and untreated hypertension presents via EMS with crushing substernal chest pain that began 90 minutes ago while watching TV. Pain radiates to his left arm and jaw. He describes it as the worst pain of his life. Associated symptoms include diaphoresis, nausea, and a "sense of doom." He took 3 aspirin at home without relief. EMS activated catheterization lab en route.

Physical Examination:

  • Vital Signs: BP 155/95 mmHg, HR 105 bpm, RR 22/min, SpO2 94% on room air
  • General: Diaphoretic, pale, severe distress, clutching chest
  • Cardiovascular: Tachycardic, S4 gallop, no murmurs
  • Lungs: Clear
  • Extremities: Cool, no edema

Workup

  • ECG: ST elevation 4-5 mm in V1-V4, reciprocal ST depression II, III, aVF, hyperacute T waves
  • Troponin I: 2.8 ng/mL (elevated, rising)
  • Coronary Angiography (emergent):
  • 100% thrombotic occlusion of proximal LAD
  • TIMI 0 flow (no distal perfusion)
  • Moderate disease in RCA
  • Post-PCI: Successful stent placement, TIMI 3 flow restored
  • Echocardiogram (post-procedure): Anterior and apical hypokinesis, EF 40%

Diagnosis

Acute anterior ST-elevation myocardial infarction due to complete LAD occlusion - "Widow maker"

Coronary Circulation Correlation:

Complete coronary occlusion cascade:

  1. Atherosclerotic plaque rupture exposes thrombogenic core
  2. Platelet adhesion, activation, aggregation
  3. Coagulation cascade → thrombus formation
  4. Complete vessel occlusion → zero flow to downstream territory

Time is myocardium:

  • After occlusion, ischemia progresses from endocardium → epicardium (wavefront phenomenon)
  • Irreversible myocyte death begins within 20-30 minutes
  • By 6 hours, most at-risk myocardium is infarcted

Coronary flow and collaterals:

  • Collateral vessels may provide some flow but usually insufficient
  • TIMI flow grades:
  • TIMI 0: No perfusion
  • TIMI 1: Minimal perfusion
  • TIMI 2: Partial perfusion
  • TIMI 3: Normal perfusion

LAD territory consequences:

  • Supplies anterior wall, septum, apex
  • Large territory → significant myocardial loss
  • High risk of: LV dysfunction, heart failure, cardiogenic shock, arrhythmias

Coronary blood flow during ischemia:

  • Loss of autoregulation in ischemic zone
  • Stunning: Prolonged dysfunction after reperfusion despite viable tissue
  • No-reflow: Microvascular obstruction despite epicardial vessel patency

Treatment

  1. Primary PCI (door-to-balloon <90 minutes):
  • Aspiration thrombectomy
  • Drug-eluting stent placement
  • Goal: Restore TIMI 3 flow
  1. Antiplatelet therapy:
  • Aspirin 325 mg (given pre-hospital)
  • P2Y12 inhibitor (prasugrel or ticagrelor loading dose)
  1. Anticoagulation: Heparin during procedure
  2. Post-MI management:
  • Beta-blocker, ACE inhibitor, statin
  • Dual antiplatelet therapy (DAPT) for 12 months
  • Cardiac rehabilitation
  1. Monitor for complications:
  • Arrhythmias, heart failure, mechanical complications

Clinical Image

Image Description: Coronary angiogram showing complete thrombotic occlusion of the left anterior descending artery with abrupt cutoff of contrast flow (TIMI 0 flow). No distal filling is visible beyond the point of occlusion.

Source: Wikimedia Commons - LAD occlusion angiography License: CC BY-SA 4.0 URL: https://commons.wikimedia.org/wiki/File:AMI_LAD_angiogram.jpg

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