What is the recommended management for significant plaque prolapse observed after coronary stent implantation?

Management of Significant Plaque Prolapse After Coronary Stent Implantation

For significant plaque prolapse after stent implantation, use intravascular imaging (IVUS or OCT) to assess the severity, and if prolapse is large (>500 µm) or associated with flow limitation, perform additional stent deployment with overlapping technique to compress the prolapsed tissue. 1, 2

Initial Assessment with Intravascular Imaging

Immediate post-stent imaging with IVUS or OCT is recommended to identify and quantify plaque prolapse. 1

• OCT provides superior resolution for detecting tissue prolapse through stent struts compared to IVUS, allowing precise measurement of prolapse depth 1
• The American College of Cardiology defines tissue protrusion as herniation of atherosclerotic plaque components through spaces between stent struts after deployment 2
• Post-procedure imaging should specifically evaluate for tissue protrusion, stent underexpansion, malapposition, and edge dissection 1

Risk Stratification Based on Prolapse Characteristics

Minor prolapse (<500 µm) without flow limitation typically does not require intervention, while large volume prolapse (>500 µm) warrants treatment, especially in acute coronary syndrome settings. 2, 3

High-Risk Features Requiring Intervention:

• Prolapse volume >500 µm on OCT imaging 3
• Acute coronary syndrome presentation (STEMI/NSTEMI) with larger atherothrombotic burden 2, 4, 5
• Associated slow flow or no-reflow phenomenon 1
• Presence of necrotic core components in prolapsed tissue (correlates with cardiac enzyme elevation) 6
• Plaque rupture or thrombus at the lesion site 4, 6

Lower-Risk Features (Observation Acceptable):

• Small prolapse volume (<500 µm) 3
• No flow limitation on angiography 2
• Stable clinical presentation 2

Treatment Algorithm for Significant Prolapse

Step 1: Overlapping Stent Deployment

Deploy an additional overlapping stent to compress prolapsed tissue when prolapse exceeds 500 µm. 3

• Overlapping stent placement significantly reduces tissue prolapse from 26% to 16% of cross-sectional slices 3
• Tissue prolapse >500 µm decreases dramatically from 15% to 2.3% with overlapping stents (p<0.001) 3
• This mechanically stabilizes the disrupted plaque and prevents further tissue extrusion 1

Step 2: Post-Dilation Optimization

After overlapping stent placement, perform high-pressure post-dilation to achieve optimal stent expansion and apposition. 1

• Target minimum stent area >5.0 mm² or 90% of distal reference segment area 1
• Ensure no residual malapposition that could harbor prolapsed tissue 1
• Confirm adequate stent expansion with repeat IVUS/OCT imaging 1

Step 3: Adjunctive Pharmacotherapy

Administer or continue GP IIb/IIIa inhibitors during and after the procedure when treating significant prolapse in ACS settings. 1

• GP IIb/IIIa inhibitors reduce major complications during complex PCI procedures 1
• Continue abciximab for 12 hours post-procedure or other GP IIb/IIIa inhibitors for 24 hours 1
• Ensure dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) is maintained 1, 7

Special Considerations and Clinical Context

Acute Coronary Syndrome Presentations

Plaque prolapse occurs more frequently in STEMI (33%) compared to stable lesions, with higher risk of complications. 4, 5

• STEMI culprit lesions have more plaque rupture (46% vs 29%), lipid pools (39% vs 25%), and thrombus (34% vs 21%) compared to NSTEMI 5
• Post-stenting CK-MB elevation is significantly greater with prolapse in AMI settings (Δ +12.3 U/L vs -4.9 U/L, p=0.002) 4
• Necrotic core component in prolapsed tissue correlates positively with cardiac enzyme elevation (r=0.489 for CK-MB, r=0.679 for troponin-I) 6

Predictors of Plaque Prolapse

Longer stent length, plaque rupture, positive remodeling, and larger necrotic core volume independently predict prolapse development. 4, 6

• Stent length is a strong predictor (OR 2.39, p=0.003) 4
• Absolute necrotic core volume (OR 1.14, p<0.001) and fibrotic volume (OR 1.09, p<0.001) independently predict prolapse 6
• Right coronary artery and chronic total occlusion lesions show higher prolapse rates 8

Critical Pitfalls to Avoid

Do not ignore significant prolapse in ACS settings, as it increases myonecrosis risk even without immediate flow compromise. 4, 6

• Prolapse is independently associated with post-stenting CK-MB elevation (OR 7.34, p<0.001) 4
• One case of delayed in-stent thrombosis at 9 months occurred with untreated >500 µm prolapse 3
• However, short-term stent thrombosis rates (1-month) are not significantly different between prolapse and non-prolapse lesions (2.4% vs 0.9%, p=0.308) 4

Do not confuse tissue prolapse with other post-stent complications that require different management. 1, 2

• Edge dissection involving media >3 mm requires coverage with additional stent 1
• Stent malapposition requires post-dilation, not overlapping stent 1
• Geographic miss requires extension of stent coverage 1

Avoid routine aspiration thrombectomy for prolapse management, as it provides no clinical benefit. 1

• Manual aspiration thrombectomy should not be performed routinely prior to or during PCI (Class 3: No Benefit, LOE A) 1
• Reserve bailout aspiration thrombectomy only for massive thrombus burden with no-reflow 1