Overview
This lecture reviews strategies for managing non-ST elevation myocardial infarction (Non-STEMI) following cardiac catheterization, with emphasis on decision-making for lesion severity, culprit identification in multivessel disease, and timing of percutaneous coronary intervention (PCI).
Management by Stenosis Severity
- Do not stent lesions with diameter stenosis <50%; consider IVUS (intravascular ultrasound) to assess true severity.
- Lesions >70% stenosis in major coronary arteries should undergo PCI as per guidelines.
- For 50–70% stenosis, use IVUS/OCT or physiology (FFR/iFR) to guide management, recognizing limitations post-MI.
- IVUS/OCT findings of plaque disruption or >70% plaque burden may justify stenting even if angiographic stenosis is not severe.
- Stenting is not recommended for minimal stenosis with plaque rupture without significant narrowing (MINOCA); treat medically.
Use of Imaging and Physiology
- IVUS and OCT are valuable for assessing ambiguous or hazy lesions and confirming true severity.
- FFR/iFR may be used in intermediate (50–70%) non-culprit lesions, but are less validated for culprit lesions in acute MI due to microvascular dysfunction.
- Traditional imaging criteria: minimal lumen area <3 mm², or 3–4 mm² with plaque disruption or >70% plaque burden may indicate need for PCI.
Culprit Lesion Identification in Multivessel Disease
- Culprit lesion is misidentified in up to 40% of Non-STEMI cases.
- Angiographic features (thrombus, ulceration, eccentricity) and advanced imaging (IVUS/OCT) are key for identifying culprit lesions.
- EKG is unreliable for localizing ischemia in Non-STEMI, as ST depression does not localize well.
- MRI is the gold standard but not cost-effective or practical for routine use.
Management of Multivessel Disease
- Perform complete multivessel PCI (not just culprit-only), supported by FIRE and BiOVASC trials.
- Ideal timing for non-culprit PCI is during index procedure or before discharge (preferably within 2 weeks), as culprit lesions are often misidentified.
- Immediate non-culprit PCI is safe and may reduce recurrent MI in Non-STEMI patients compared to delayed intervention.
Key Terms & Definitions
- Non-STEMI — Non-ST Elevation Myocardial Infarction, a type of heart attack without full-thickness heart muscle damage.
- PCI (Percutaneous Coronary Intervention) — Procedure to open narrowed coronary arteries.
- IVUS (Intravascular Ultrasound) — Imaging tool to assess vessel lumen and plaque characteristics.
- OCT (Optical Coherence Tomography) — High-resolution imaging for coronary artery evaluation.
- FFR (Fractional Flow Reserve)/iFR (Instantaneous Wave-Free Ratio) — Physiological measurements to assess the significance of coronary stenosis.
- MINOCA — Myocardial Infarction with Nonobstructive Coronary Arteries.
- Plaque Disruption — Plaque rupture or erosion seen on imaging, indicating vulnerable lesion.
Action Items / Next Steps
- Review FIRE, BiOVASC, and referenced early invasive trials for further evidence.
- Practice identifying culprit lesions using angiography and imaging features.
- Stay updated on guideline recommendations for Non-STEMI management and PCI timing.