The QFR computation improved the diagnostic accuracy of 3-dimensional quantitative coronary angiography-based identification of stenosis significance. The favorable results of cQFR that does not require pharmacologic hyperemia induction bears the potential of a wider adoption of FFR-based lesion assessment through a reduction in procedure time, risk, and costs.

Pressure wire-based fractional flow reserve is considered the standard of reference for evaluation of the ischemic potential of coronary stenoses and the expected benefit from revascularization. Accordingly, its application in daily practice or for research purposes has to be as standardized as possible to avoid technical or operator-related artifacts in pressure recordings. This document proposes a standardized way of acquiring, recording, interpreting, and archiving the pressure tracings for daily practice and for the purpose of clinical research involving a core laboratory. Proposed standardized steps enhance the uniformity of clinical practices and data interpretation.

T he optimal treatment of patients with stable coronary artery disease (CAD) remains a matter of ongoing debate. Although revascularization provides an accepted symptomatic benefit, controversy lingers on its prognostic value when added to contemporary optimal medical care.1 Protagonists of medical therapy stress that revascularization, especially with percutaneous coronary intervention (PCI), does not reduce rates of death or myocardial infarction.2 Protagonists of mechanical therapy counter that most revascularization studies were based on anatomic guidance only, with visual estimation of stenosis severity from the coronary angiogram.3 Because ≤39% of angiographically obstructive coronary stenoses lack functional significance, no benefit should be expected from revascularizing nonischemic myocardium. 4 As a result, outcome results from existing trials are confounded by the neutral or negative effects arising from unnecessary interventions.

Absolute coronary blood flow (in L/min) and R (in mm Hg/L/min or Wood units) can be safely and reproducibly measured with continuous thermodilution. This approach constitutes a new opportunity for the study of the coronary microcirculation.