Anatomical Assessment Versus Pull Back RFR Measurement

The READY register is a multicenter open label registry of patients underwent invasive intracoronary FFR and RFR measurement using the Quantien system. The register collects clinical and epidemiological data of patients scheduled for invasive coronary physiology.

Angiographic evaluation protocol:

Coronary diagnostic angiography is performed according to the routine clinical practice. The visual estimate of the diameters stenosis % of the culprit lesion(s) should be input prospectively in the modified Syntax segmentation scheme (https://coronart.hu/) where the corresponding ventricular segments supply is indicated on a polar map. On the same time, the operator is required to record characterize the coronary vessel disease as focal, diffuse or mixed type, and to document his plan for angioplasty on the basis of the visual assessment. The number and length of stents planned for implantation for each patient should be also documented on the basis of visual estimation before the physiological measurements.

Invasive coronary physiology assessment protocol:

PressurewireX will be advanced distally to the investigated lesion(s) of a coronary artery. Resting and hyperemic average pressures will be determined in this distal position (in FFR mode).

A resting manual pullback with 1-2 mm/s speed will be performed (in RFR mode) under simultaneous fluoroscopic control. The "store fluoro" option of the X-ray system allows the co-registration of the pressure drop(s) to the epicardial lesion(s) on the basis of the same time scale of the pullback and the stored fluoro. The use of marker(s) in the Quantien software can enhance the identification of the culprit interval(s) of the pressure pullback curve and the related angiographic details.

A substudy of the register is planned to achieve extended physiological assessment in patients with the suspicion of microvascular disease in line with the latest ESC guideline stressing the role of microcirculatory dysfunction in the adverse outcome events in patients with non-significant coronary stenoses by FFR (class IIa, level B recommendation).

According to the intracoronary average pressure values the pressure bounded CFR interval will be calculated (CFRpb). If the cut-off value CFR=2 lies inside the defined CFRpb interval, then a novel CFR calculation based on three-dimensional reconstruction and simple flow dynamic modelling will be performed to get the exact CFRp-3D value in order to diagnose or exclude microvascular disease. One simple possibility for the characterization of the microvasculature is to define the CFR/FFR index. This value below 2 indicate impaired microvascular vasodilator capacity. For getting more precise microvascular parameter, the flow modeling using the data of the 3D coronary reconstruction and the intracoronary pressure values will provide the microvascular resistance reserve (MRR).

Offline 3D angiographic reconstruction will be performed from the selected two angiograms of good quality, with at least 25◦ difference in angle, using dedicated 3D software.

Statistical Analysis:

Normal distribution will be tested. Descriptive statistics are planned as mean and SD, median (interquartile range), or counts (%) as appropriate. Categorical variables will be compared with the Pearson χ2test. Correlation among variables will be determined by calculating Spearman ρ correlation coefficient. All analyses will be performed in Medcalc program.

Eligibility Criteria:
Inclusion Criteria:

* At least one lesion on coronary artery branch greater than 2 mm in diameter assessed as 40-90% narrowing by visual estimation
* Invasive intracoronary FFR and RFR measurement using the Quantien system according to clinical decision

Exclusion Criteria:

* Patients with acute coronary syndrome
* Left main disease
* Contraindication for adenosine
* Coronary artery bypass graft on the investigated vessel
* Severe renal insufficiency (estimated glomerular filtration rate \<30 ml/min/1.73 m2)
* Coronary angiography and pressure recordings not suitable for evaluation