Myocardial Perfusion Imaging and Fractional Flow Reserve-Therapeutic Strategy Based on Myocardial Ischemia Evaluation in Patients with Coronary Artery Disease.

Indications for percutaneous coronary intervention (PCI) among patients with stable coronary artery disease (CAD) have historically been decided after morphological evaluation using coronary angiography (CAG). Recently, the importance of physiological evaluation has been recognized using either myocardial perfusion imaging (MPI) or fractional flow reserve (FFR). The results of the recent COURAGE trial showed that PCI did not improve mortality rates in medically optimized patients with stable CAD. However, a nuclear sub-study of that trial in which participants underwent MPI before and after PCI+ optimal medical therapy (OMT), found a greater reduction in ischemia compared with OMT alone. Moreover, the unadjusted risk for death or myocardial infarction in patients with ischemia reduction was lower. In contrast, the FAME study indicated that FFR-guided PCI improved the outcomes of patients with multi-vessel CAD compared with angiography-guided PCI. The FAME II study also indicated the validity of FFR-guided PCI. Thus, FFR evaluation of ischemia is becoming more popular worldwide from the viewpoint of intervention. Both MPI and FFR reflect physiological ischemia, but their findings do not necessarily match up. One reason is that MPI reflects myocardial ischemia whereas FFR reflects coronary artery ischemia. Thus, cardiologists regard the findings of these modalities conflicting when considering practicality and diagnostic accuracy. This article compares the features of MPI and FFR and discusses an appropriate strategy with which to evaluate CAD.