256 Impact of physiologically diffuse vs. focal pattern of coronary disease on quantitative flow reserve diagnostic accuracy
Abstract Aims Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) disagree in ∼20% of intermediate coronary lesions. The physiological pattern of disease has a significant influence on FFR-iFR discordance. However, if the pattern of disease (diffuse vs. focal) impacts on QFR accuracy and on its agreement with FFR and iFR remains unknown. Methods and results 194 unselected patients with 224 intermediate coronary lesions were investigated with iFR, FFR and QFR. The physiological pattern of disease was independently assessed with iFR Scout pullback in all the cases by two expert interventional cardiologists who were blinded to the clinical presentation, patient characteristics, coronary angiography and QFR results. A predominantly physiologically focal pattern was observed in 81 (36.2%) lesions, whereas a predominantly physiologically diffuse was observed in 143 (63.8%) cases. QFR demonstrated a significant correlation (r = 0.581, P < 0.001) and a substantial agreement with iFR, both in diffuse (AUC = 0.798) and in focal (AUC = 0.812) pattern of disease. Disagreement between QFR and iFR was observed in 51 (22.8%) lesions, consisting of iFR+/QFR − (64.7%) and iFR−/QFR + (35.3%). Notably, the physiological pattern of disease was the only variable significantly associated with iFR/QFR disagreement. In particular, coronary lesions with iFR+/QFR− demonstrated a significantly higher prevalence of predominantly physiologically diffuse pattern of disease compared with the subgroup with iFR−/QFR + [81.3% (26 of 32) vs. 55.6% (10 of 18); P = 0.012]. QFR virtual pullback demonstrated an excellent agreement (83.9%) with iFR Scout pullback in classifying the physiological pattern of disease. Conclusions QFR has a good diagnostic accuracy in assessing myocardial ischemia independently of the pattern of coronary disease. However, the physiological pattern of disease has an influence on the QFR/IFR disagreement, which occurs in ∼20% of the cases. The QFR virtual pullback correctly defined the physiological pattern of disease in the majority of the cases using the iFR pullback as reference.