Randomized Comparison of Fractional Flow Reserve and Instantaneous Wave Free Ratio in Serial Disease

Area of Science:

• Cardiovascular Medicine
• Interventional Cardiology
• Physiological Measurement

Background:

• Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are crucial for guiding percutaneous coronary intervention (PCI).
• Predicting post-PCI physiological outcomes using FFR or iFR pullback gradients (FFRΔ or iFRΔ) is common but lacks validation.
• Serial or diffuse coronary artery disease presents unique challenges for physiological assessment.

Purpose of the Study:

• To compare the accuracy of FFRΔ, iFRΔ, and a calculated FFR (FFRcalc) in predicting post-PCI physiology.
• To evaluate the effectiveness of these methods in patients with serial or diffuse coronary disease.
• To determine the best approach for assessing physiological results after PCI in complex lesions.

Main Methods:

• Randomized trial comparing FFR-guided versus iFR-guided PCI in patients with a target lesion and additional disease.
• Performance of blinded FFR and iFR pullbacks before and after target lesion PCI.
• Primary outcome measured as the error between predicted and actual post-PCI physiological values.

Main Results:

• iFRΔ (4%) and FFRcalc (-5%) showed significantly lower predictive errors compared to FFRΔ (12%).
• FFRΔ and iFRΔ missed significant residual disease in 36% and 34% of cases, respectively.
• FFRcalc demonstrated a lower rate of missed residual disease (14%) compared to FFRΔ and iFRΔ.

Conclusions:

• FFR and iFR pullback gradients can overestimate PCI benefits and miss significant residual ischemia in a substantial proportion of patients.
• The FFRcalc method offers a more accurate prediction of post-PCI physiology compared to FFRΔ and iFRΔ.
• Routine re-measurement of FFR or iFR after PCI is recommended for patients with serial coronary disease.