When is angioplasty contraindicated?

Contraindications to Angioplasty

Angioplasty should not be performed when there are absolute contraindications including unprotected left main coronary artery stenosis >50%, absence of a significant obstructing lesion, multivessel disease with severe diffuse atherosclerosis better suited for bypass surgery, or when there is no formal cardiac surgical program within the institution. 1

Absolute Contraindications

1. No significant obstructing lesion - Angioplasty should not be performed when there is no hemodynamically significant stenosis 1

2. Unprotected left main coronary artery stenosis >50% - A significant obstruction (>50%) in the left main coronary artery that is not protected by at least one completely patent bypass graft to the left anterior descending or left circumflex artery 1

3. Severe diffuse multivessel disease - When an alternative form of revascularization (like CABG) would be unequivocally more efficacious 1

4. No cardiac surgical backup - Performing angioplasty at an institution without a formal cardiac surgical program 1

Relative Contraindications

1. Coagulopathy - Bleeding abnormalities or hypercoagulable states increase risks of serious bleeding or thrombotic occlusion 1

2. Absence of ischemia - No clinical evidence for spontaneous or inducible myocardial ischemia 1

3. High risk of cardiogenic shock - Particularly in multivessel angioplasty where occlusion of any vessel could result in cardiogenic shock (e.g., patients with large areas of previous myocardial dysfunction) 1

4. Low anticipated success rate - Such as:

   • Chronic total occlusions >3 months old 1, 2
   • Subtotal lesions exceeding 20 mm in length 1
   • Heavily calcified lesions 2
   • Extreme vessel angulation 2

5. Borderline stenotic lesions - Lesions with <60% stenosis should generally not be dilated due to risk of developing more severe restenosis 1

6. Variant/vasospastic angina - In patients with <60% stenoses 1

7. Non-infarct related artery - During the acute phase of myocardial infarction in patients with multivessel disease 1

Risk Stratification Considerations

The American College of Cardiology classifies lesions into three types that help determine appropriateness of angioplasty:

• Type A lesions: Anticipated success rate ≥85% with low risk of abrupt vessel closure
• Type B lesions: Success rate 60-85% with moderate risk of abrupt closure
• Type C lesions: Unacceptably low success rate (<60%) or high risk of abrupt closure 1

Special Considerations

1. LAD Chronic Total Occlusions:

   • Higher restenosis rates compared to other coronary vessels
   • Supplies large area of viable myocardium, making intervention particularly challenging
   • Increased risk of complications including abrupt vessel closure, damage to collateral vessels, and perforation 2

2. Patient Risk Profile:

   • Low-risk patients (mortality risk <2%) may not receive mortality benefit from primary angioplasty versus thrombolytic therapy 3
   • Previous myocardial infarction appears to be a risk factor for lower success rates and increased complications 4

Common Pitfalls to Avoid

1. Ignoring lesion characteristics - Failure to properly assess lesion type (A, B, or C) can lead to attempting angioplasty in situations with unacceptably low success rates

2. Proceeding without surgical backup - Always ensure cardiac surgical support is available in case of complications

3. Dilating borderline lesions - Angioplasty of lesions <60% stenosis without objective evidence of ischemia can lead to worse outcomes than medical management

4. Underestimating risk in multivessel disease - Particularly when occlusion of any single vessel could lead to cardiogenic shock

By carefully evaluating these contraindications and risk factors, clinicians can make appropriate decisions about when angioplasty should not be performed, prioritizing patient safety and optimizing outcomes.