Impact of Revascularization on Absolute Myocardial Blood Flow as Assessed by Serial [15O]H2O Positron Emission Tomography Imaging: A Comparison With Fractional Flow Reserve.

Abstract

The main goal of coronary revascularization is to restore myocardial perfusion in case of ischemia, causing coronary artery disease. Yet, little is known on the effect of revascularization on absolute myocardial blood flow (MBF). Therefore, the present prospective study assesses the impact of coronary revascularization on absolute MBF as measured by [15O]H2O positron emission tomography and fractional flow reserve (FFR) in patients with stable coronary artery disease. Fifty-three patients (87% men, mean age 58.7±9.0 years) with suspected coronary artery disease were included prospectively. All patients underwent serial [15O]H2O positron emission tomography perfusion imaging at baseline and after revascularization by either percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery. FFR was routinely measured at baseline and directly post-PCI. After revascularization, regional rest and stress MBF improved from 0.77±0.16 to 0.86±0.25 mL/min/g and from 1.57±0.59 to 2.48±0.91 mL/min/g, respectively, yielding an increase in coronary flow reserve from 2.02±0.69 to 2.94±0.94 (P<0.01 for all). Mean FFR at baseline improved post-PCI from 0.61±0.17 to 0.89±0.08 (P<0.01). After PCI, an increase in FFR paralleled improvement in absolute myocardial perfusion as reflected by stress MBF and coronary flow reserve (r = 0.74 and r = 0.71, respectively, P<0.01 for both). PCI demonstrated a greater improvement of regional stress MBF as compared with coronary artery bypass graft surgery (1.14±1.11 versus 0.66±0.69 mL/min/g, respectively, P=0.02). However, patients undergoing bypass grafting had a more advanced stage of coronary artery disease and more incomplete revascularizations. Successful coronary revascularization has a significant and positive impact on absolute myocardial perfusion as assessed by serial quantitative [15O]H2O positron emission tomography. Notably, improvement of FFR after PCI was directly related to the increase in hyperemic MBF.