Validation of coronary flow reserve measurements by thermodilution in clinical practice

Background: Coronary flow reserve (CFR) and fractional flow reserve (FFR) provide complementary information on the coronary circulation. Using a pressure wire, it is possible to calculate CFR by thermodilution (CFR_thermo), so that FFR and CFR can be measured with a single guide wire. The present multicentric study was performed to compare the feasibility of CFR _thermo obtained with an improved algorithm and a standardized injection technique and its agreement with Doppler-derived CFR (CFR _Doppler). Methods and results: In 86 patients with coronary artery disease recruited during 1 week in eight centres FFR, CFR_thermo and CFR_Doppler were measured. FFR could be obtained in all patients (100%). An optimal CFR_Doppler could be obtained in 69% of the patients. CFR_thermo could be obtained in 97% of the patients. A significant correlation was found between CFR_Doppler and CFR _thermo (r=0.79, P<0.0001) but CFR_thermo tended to be higher than CFR_Doppler. Conclusions: In a setting close to 'real world' practice, this multicentric study confirms the feasibility and reliability of thermodilution-derived CFR. In addition, the safety and the swiftness of assessing FFR and CFR with one single guide wire makes the latter a unique clinical tool for the evaluation of the coronary circulation.