Does every stent require postdilatation?

Coronary Stent Postdilatation: Indications and Approach

Not every stent requires postdilatation, but many do to achieve optimal expansion and reduce complications. The decision should be based on lesion characteristics, stent deployment results, and imaging guidance when available.

Indications for Postdilatation

When Postdilatation is Necessary:

• Suboptimal stent expansion on angiography or intravascular imaging
• Complex lesions (calcified, fibrotic, bifurcation)
• Left main and bifurcation lesions 1
• Drug-eluting stent (DES) placement, especially for in-stent restenosis 2
• Stent deployment at pressures ≤14 atm 3
• Residual stenosis >20% after initial deployment 3

When Postdilatation May Be Avoided:

• Simple, non-calcified lesions with optimal expansion on initial deployment
• Many stable, non-occlusive lesions in the absence of extensive calcification 1
• When direct stenting achieves optimal expansion (though this is uncommon) 4, 5

Evidence Supporting Postdilatation

Intravascular ultrasound (IVUS) studies have demonstrated that stent underexpansion is common even with modern delivery systems:

• Up to 66% of drug-eluting stents show underexpansion after initial deployment 2
• In one study, 84.3% of directly stented lesions required postdilatation to optimize expansion when assessed by IVUS 4
• Postdilatation significantly increases minimal stent area (from 4.3±0.3 to 5.6±0.4 mm²) 2

Optimal stent expansion is crucial because:

• Underexpanded stents are associated with higher rates of stent thrombosis and target vessel revascularization 6
• Proper drug delivery from DES requires good apposition to vessel wall 1

Approach to Postdilatation

1. For most lesions:

   • Use non-compliant balloons for postdilatation
   • Size balloon to reference vessel diameter
   • Use high pressure (>14 atm) to achieve optimal expansion

2. For bifurcation lesions:

   • Final kissing balloon dilatation is recommended when two stents are used 1
   • Special attention to adequate sizing and deployment for left main and bifurcation lesions 1

3. For complex/calcified lesions:

   • Consider rotablation for severely fibrotic or calcified lesions that cannot be adequately dilated 1
   • Use intravascular imaging guidance when available

Optimization Assessment

The gold standard for assessing optimal stent expansion is intravascular imaging:

• Optimal stent deployment is defined as stent minimal lumen diameter ≥90% of reference vessel diameter 3
• Without postdilatation, optimal stent deployment is achieved in only 35.6-64.9% of cases 3
• With postdilatation, this increases to 56.5% 3

Common Pitfalls to Avoid

1. Underestimating the need for postdilatation:

   • Angiography alone may underestimate the need for postdilatation
   • In one study, angiography identified need for postdilatation in only 23.6% of lesions, while IVUS identified 84.3% 4

2. Inappropriate balloon sizing:

   • Oversized balloons can cause edge dissections or perforations
   • Undersized balloons will not achieve optimal expansion

3. Insufficient pressure:

   • Low pressure postdilatation may not overcome stent recoil or resistance from calcified lesions
   • Stent deployment at pressures ≤14 atm often results in suboptimal expansion 3

4. Neglecting postdilatation with DES:

   • The very low restenosis rates with DES have led some operators to neglect postdilatation
   • However, stent underexpansion remains a significant risk factor for stent thrombosis and target vessel failure even with DES 6

In conclusion, while not every stent requires postdilatation, the evidence suggests that most do benefit from it, particularly in complex lesions and when using drug-eluting stents. Intravascular imaging provides the most accurate assessment of the need for and results of postdilatation.