Deconstructing the idol of fractional flow reserve using the IDEAL report.

Percutaneous coronary intervention (PCI) in patients with chronic stable coronary artery disease (CAD) has not yet been proven to reduce the incidence of myocardial infarction or death. The outcome after PCI is, however, dependent on the amount of myocardial ischaemia, which is—among others—influenced by the tightness and proximity of the coronary atherosclerotic lesion. Invasive ischaemia testing is relevant, because only a minority of patients with stable CAD undergo non-invasive stress testing for ischaemia detection prior to elective PCI; it guides ad-hoc PCI or its deferral. The latter aims at preventing adverse effects of a PCI, which would be ineffective on symptoms in the absence of ischaemia. Invasive ischaemia testing does not, however, detect ECG-derived ischaemia, nor does it assess the amount of ischaemia or systematically account for the proximity of the stenotic lesion, i.e. for the ischaemic area at risk for infarct. However, most often it provides a mere estimate of the stenosis tightness, and, rarely, coronary pressurederived hyperaemic fractional flow (fractional flow reserve, FFR) for the description of the functional relevance of the stenosis. This practical but idolized reference for invasive functional coronary stenosis assessment (FFR) is challengeable by the presently published IDEAL report, which translates—at least in part—data from coronary physiological animal experiments into the human clinical setting of structurally overt CAD.