Explanation of Postprocedural Fractional Flow Reserve Below 0.85.

Area of Science:

• Cardiology
• Interventional Cardiology
• Medical Imaging

Background:

• Fractional flow reserve (FFR) post-percutaneous coronary intervention (PCI) predicts cardiovascular events.
• Angiography alone often fails to explain low post-PCI FFR values.

Purpose of the Study:

• To investigate the underlying causes of low post-PCI FFR using intravascular ultrasound (IVUS).
• To correlate IVUS findings with FFR values in a large patient cohort.

Main Methods:

• Prospective single-center registry (FFR SEARCH) of 1000 patients.
• FFR measurements performed post-PCI.
• High-definition IVUS analysis in 100 vessels with FFR ≤0.85 and 20 with FFR >0.85.

Main Results:

• In vessels with FFR ≤0.85, mean FFR was 0.79±0.05.
• Significant residual lesions (proximal/distal) found in 29%/30% of vessels.
• Stent underexpansion (74%) and malapposition (22%) were common.
• Clear focal luminal narrowing identified in 54% of analyzed vessels.
• Minimal stent area was significantly smaller in vessels with FFR ≤0.85.

Conclusions:

• Intravascular ultrasound identified focal luminal narrowing as a significant factor in cases with low post-PCI FFR.
• Smaller minimal stent area is associated with reduced post-PCI FFR.