Introduction: In case of ischemia causing coronary artery disease (CAD), the main goal of myocardial revascularization is to restore myocardial perfusion. 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 (PET) and fractional flow reserve (FFR) in patients with stable CAD.
Methods: 53 Patients (87% men, age 58.7 ± 9.0 years) with suspected CAD were included prospectively. All patients underwent serial [15O]H2O PET perfusion imaging at baseline and after revascularization by either percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery (CABG). FFR was routinely measured at baseline and directly post-PCI. Sequential absolute myocardial perfusion was compared and the relationship with FFR was explored.
Results: After revascularization, stress MBF improved from 1.57 ± 0.59 to 2.48 ± 0.91 mL·min-1·g-1 (p < 0.01). Also rest MBF and coronary flow reserve (CFR) increased, from 0.77 ± 0.16 to 0.86 ± 0.25 mL·min-1·g-1 and 2.02 ± 0.69 to 2.94 ± 0.94, respectively, p < 0.01 for both. Relative flow reserve (RFR) for single- and two-vessel disease increased from 0.65 ± 0.18 towards 0.98 ± 0.15 (p < 0.01). 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, CFR and RFR (r > 0.70 and p < 0.01 for all). The only independent predictor of stress MBF restoration among traditional cardiovascular risk factors appeared to be current smoking. PCI, however, demonstrated a greater improvement of stress MBF as compared with CABG (1.10 ± 1.10 vs. 0.64 ± 0.69 mL·min-1·g-1, respectively, p = 0.02).
Conclusions: Successful coronary revascularization has a significant and positive impact on absolute myocardial perfusion as assessed by serial quantitative [15O]H2O PET. Notably, improvement of FFR after PCI was paralleled by a concomitant increase in MBF. Whereas most cardiovascular risk factors did not predict myocardial perfusion restoration, PCI succeeded in a greater improvement than CABG.