Continuous Thermodilution Method to Assess Coronary Flow Reserve

ABSTRACT Coronary flow reserve (CFR) is a well-validated flow-based physiological parameter that has shown value in clinical risk stratification. CFR can be invasively assessed, classically by Doppler and, more recently, by thermodilution with saline boluses (CFRthermo-bolus). Alternatively, continuous thermodilution is a novel operator-independent, highly-reproducible technique to invasively quantify maximum absolute coronary flow (AF). This study aimed to assess the feasibility of this method to quantify resting AF and to determine CFR (CFRThermo-infusion) as compared with CFRthermo-bolus. Sixty-two consecutive patients with suspicion of coronary disease and absence of significant epicardial lesions were prospectively investigated. AF at maximal hyperemia (20mL/min) and at lower infusion rates (6-8-10-12 mL/min) were systematically measured using a dedicated catheter and a temperature/pressure guidewire. The absence of baseline Pd/Pa decrease at 6 (0.15±0.2%), 8 (0.17±0.18%) and 10mL/min (0.2±0.12%) demonstrated absence of hyperemia at ≤10mL/min (all p=NS). However, at 12mL/min hyperemia was confirmed by a significant decrease in Pd/Pa (1.3±1.5%,p