What are the indications for coronary stent placement in patients with inducible ischemia on cardiac MRI (Magnetic Resonance Imaging)?

Indications for Coronary Stents with Inducible Ischemia on Cardiac MRI

Coronary stent placement is indicated in patients with inducible ischemia on cardiac MRI who have one or more significant (>70% diameter) coronary artery stenoses and unacceptable angina despite guideline-directed medical therapy. 1

Primary Indications for Coronary Stenting

Class I Recommendations (Strong Evidence)

• Coronary stenting is beneficial for symptom improvement in patients with one or more significant (>70% diameter) coronary artery stenoses amenable to revascularization who have unacceptable angina despite guideline-directed medical therapy 1
• Stenting should be considered when inducible ischemia is demonstrated on cardiac MRI and corresponds to a significant coronary stenosis identified on angiography 1

Class IIa Recommendations (Reasonable to Perform)

• Coronary stenting is reasonable for symptom improvement in patients with significant stenoses and unacceptable angina when guideline-directed medical therapy cannot be implemented due to medication contraindications, adverse effects, or patient preferences 1
• PCI is reasonable in patients with previous CABG who have significant stenoses associated with ischemia and unacceptable angina despite medical therapy 1

Physiological Assessment for Decision Making

Fractional Flow Reserve (FFR) Guidance

• An FFR ≤0.75 identifies coronary stenoses causing inducible myocardial ischemia with high sensitivity (88%), specificity (100%), and overall accuracy (93%) 1
• For intermediate lesions (40-70% stenosis), when FFR is ≤0.75, the stenosis is considered hemodynamically significant and PCI can be supported 1
• If FFR is ≥0.80, the clinical benefit of PCI is questionable, and medical therapy may be preferred 1
• The FFR range of 0.75-0.80 represents a gray zone requiring clinical judgment 1

Coronary Flow Reserve (CFR)

• A CFR <2.0 correlates with reversible myocardial perfusion defects with high sensitivity (86-92%) and specificity (89-100%) 1
• In patients with angina and nonobstructive coronary artery disease, diminished coronary flow reserve (CFR <2.5) identifies patients with inducible ischemia and abnormal physiological response to exercise 2

Special Considerations Based on Coronary Anatomy

Multivessel Disease

• It is reasonable to choose CABG over PCI for symptom improvement in patients with complex 3-vessel CAD (e.g., SYNTAX score >22), with or without involvement of the proximal LAD artery 1
• In patients with multivessel disease, especially those with diabetes, CABG is generally superior to PCI and to medical therapy alone 1

Post-STEMI Management

• Noninvasive testing for ischemia should be performed before discharge to assess the presence and extent of inducible ischemia in STEMI patients who have not had coronary angiography and do not have high-risk clinical features 1
• Noninvasive testing might be considered to evaluate the functional significance of a non-infarct artery stenosis previously identified at angiography 1

When to Avoid Coronary Stenting

Class III Recommendations (Potentially Harmful)

• PCI should not be performed with the primary intent to improve survival in patients with coronary stenoses that are not anatomically or functionally significant (e.g., <70% diameter non-left main stenosis, FFR >0.80, no or mild ischemia on testing) 1
• PCI with coronary stenting should not be performed if the patient is unlikely to tolerate and comply with dual antiplatelet therapy for the appropriate duration 1

Management Algorithm for Patients with Inducible Ischemia on Cardiac MRI

1. Confirm significant coronary stenosis:

   • Perform coronary angiography to identify stenoses corresponding to areas of inducible ischemia on cardiac MRI 1
   • Consider physiological assessment (FFR, CFR) for intermediate lesions 1

2. Evaluate medical therapy status:

   • Ensure guideline-directed medical therapy has been optimized 1
   • Assess patient's symptom burden despite medical therapy 1

3. Decision for revascularization:

   • If significant stenosis (>70%) AND unacceptable symptoms despite medical therapy → Proceed with PCI 1
   • If intermediate stenosis (40-70%) → Use FFR/CFR to guide decision (FFR ≤0.75 or CFR <2.0 supports PCI) 1
   • For complex multivessel disease → Consider CABG over PCI 1

4. Post-revascularization management:

   • Ensure appropriate dual antiplatelet therapy 1
   • Consider cardiac rehabilitation 1
   • Implement aggressive risk factor modification 1

Important Caveats and Pitfalls

• The absence of critical coronary lesions does not rule out the diagnosis of acute coronary syndrome if clinical presentation was suggestive and biomarkers were positive 1
• Avoid PCI in lesions that are not functionally significant as determined by FFR >0.80 or absence of significant ischemia on cardiac MRI 1
• Remember that patients with coronary microvascular dysfunction may have inducible ischemia on cardiac MRI despite nonobstructive coronary artery disease, requiring different management approaches 2
• Recent evidence has generated controversy regarding the value of routine early revascularization compared with optimal medical therapy alone, particularly in stable patients 1