Abstract 3335: Invasive Assessment of Coronary Physiology Using A Pressure Wire Correlates with Cardiac Positron Emission Tomography in Patients with Coronary Disease.
Background: Coronary flow reserve (CFR) is a method for interrogating the physiologic state of both the epicardial artery and microcirculation. Previous studies have validated CFR measurements obtained by Doppler flow wires in animals and patients with coronary artery disease (CAD). Coronary pressure wires are valuable clinical tools for assessing fractional flow reserve (FFR) and the physiological significance of epicardial stenosis. CFR may be obtained from a pressure wire when the pressure sensor acts as a thermister using a thermodilution technique. Positron emission tomography (PET) is the noninvasive gold standard for assessing myocardial flow. No data are available comparing CFR measured noninvasively with PET to invasive, pressure wire-derived CFR in patients with CAD.
Methods: In 12 patients, CFR of the left anterior descending (LAD) artery was measured on the same day noninvasively with cardiac PET (CFRPET) and invasively with a coronary pressure wire and thermodilution technique (CFRThermo). PET imaging was performed using 10 mCi of [13N] ammonia both at rest and during maximum hyperemia with intravenous adenosine. Rest and peak flow was determined from dynamic PET images by using a curve fitting technique with two-compartment tracer kinetics. CFRPET was defined as hyperemic flow divided by resting flow. The mean transit time of saline injected down the artery was measured using a thermodilution technique. CFRThermo was defined as resting mean transit time, which correlates inversely with flow, divided by the hyperemic mean transit time.
Results: CFRThermo correlated significantly with CFRPET (1.9 ± 1.1 vs. 1.9 ± 1.0; r=0.69, p=0.02). Coronary angiography of the LAD revealed > 70% stenosis in 6 of 12 patients. In all 6 patients, FFR was < 0.60 and both CFRThermo and CFRPET were < 2.5.
Conclusion: Invasive CFRThermo correlated significantly with noninvasive CFRPET in patients with CAD and a range of epicardial stenosis. These data were obtained in synchrony with clinical measurements of FFR. This validated invasive method for assessing both the physiological significance of epicardial stenosis and the state of the microvasculature in patients with CAD should be useful in evaluating therapies which target the entire coronary circulation.