Comparison of Doppler Flow Velocity and Thermodilution Derived Indexes of Coronary Physiology

The aim of this study was to compare Doppler flow velocity and thermodilution-derived indexes and to determine the optimal thermodilution-based diagnostic thresholds for coronary flow reserve (CFR). The majority of clinical data and diagnostic thresholds for flow-based indexes are derived from Doppler measurements, and correspondence with thermodilution-derived indices remain unclear. An international multicenter registry was conducted among patients who had coronary flow measurements using both Doppler and thermodilution techniques in the same vessel and during the same procedure. Physiological data from 250 vessels (in 149 patients) were included in the study. A modest correlation was found between thermodilution-derived CFR (CFR ) and Doppler-derived CFR (CFR ) (r = 0.36; P < 0.0001). CFR overestimated CFR (mean 2.59 ± 1.46 vs 2.05 ± 0.89; P < 0.0001; mean bias 0.59 ± 1.24 by Bland-Altman analysis), the relationship being described by the equation CFR = 1.04 × CFR + 0.50. The commonly used dichotomous CFR threshold of 2.0 had poor sensitivity at predicting a CFR value