Fractional flow reserve from coronary CT angiography compared with quantitative flow ratio in complex CAD

Area of Science:

• Cardiovascular Imaging and Interventions
• Computational Fluid Dynamics in Cardiology
• Coronary Artery Disease Assessment

Background:

• Diagnostic concordance between non-invasive FFR_CT and invasive angiography-derived QFR and μFR is often assumed.
• Accurate assessment of coronary artery disease severity is crucial for guiding revascularization strategies.

Purpose of the Study:

• To evaluate the diagnostic concordance of FFR_CT, QFR, and μFR in patients with multi-vessel coronary artery disease.
• To compare the ability of these methods to classify lesion phenotype (diffuse vs. focal).

Main Methods:

• Post-hoc analysis of 114 patients from the FASTTRACK CABG trial with de-novo three-vessel and/or left-main coronary artery disease.
• Coronary CT angiography (CCTA) and invasive coronary angiography (ICA) data were analyzed in a core lab.
• FFR_CT, QFR, and μFR were calculated at bifurcation points; virtual PPGi assessed lesion phenotype.

Main Results:

• Mean distal estimates of FFR_CT (0.70), QFR (0.71), and μFR (0.69) were similar across 199 vessels.
• QFR was significantly higher than FFR_CT and μFR in proximal bifurcations, potentially underestimating lesion severity.
• Concordance for lesion phenotype classification was poor between FFR_CT, QFR, and μFR (kappa < 0.16).

Conclusions:

• QFR values in proximal bifurcations may differ from FFR_CT and μFR, impacting revascularization decisions.
• The pathophysiological classification of coronary lesions as diffuse or focal shows poor correlation among the assessed methods.
• Further investigation is needed to understand the clinical implications of discrepancies in lesion severity and phenotype assessment.