Clinical Significance of the Difference Between Fractional Flow Reserve and Quantitative Flow Ratio

Area of Science:

• Cardiology
• Interventional Cardiology
• Physiology

Background:

• Quantitative flow ratio (QFR) is an angiography-based index for assessing coronary functional stenosis, showing good correlation with fractional flow reserve (FFR).
• The clinical significance of the difference between QFR and FFR (delta QFR-FFR) in patients undergoing FFR-guided percutaneous coronary intervention (PCI) was explored.
• Understanding delta QFR-FFR may offer insights into coronary microvascular function and diffuse disease.

Purpose of the Study:

• To investigate the clinical significance of delta QFR-FFR in patients undergoing FFR-guided elective PCI.
• To evaluate delta QFR-FFR as a predictor of major adverse cardiovascular events (MACE).

Main Methods:

• Retrospective analysis of 301 patients with chronic coronary syndrome who underwent FFR-guided PCI and QFR assessment.
• Patients were stratified into tertiles based on pre-PCI delta QFR-FFR.
• Clinical characteristics, physiological parameters, and MACE were compared across tertiles; delta QFR-FFR was analyzed as a predictor of MACE.

Main Results:

• Lower delta QFR-FFR was associated with impaired microvascular function, including lower QFR pullback pressure gradient, higher index of microcirculatory resistance, and reduced post-PCI coronary flow reserve.
• MACE occurred significantly more often in patients with delta QFR-FFR less than -0.060 (log-rank P=0.006).
• Cox regression identified lower delta QFR-FFR as an independent predictor of MACE.

Conclusions:

• Pre-PCI delta QFR-FFR is linked to microvascular dysfunction and diffuse coronary artery disease.
• A lower delta QFR-FFR value predicts an increased risk of MACE following FFR-guided revascularization.
• Delta QFR-FFR shows potential as a valuable tool for risk stratification in patients undergoing PCI.