Initial results of the READY registry: comparison of visual and physiological lesion characterization and the effect of hydrostatic pressure correction

Abstract We aimed to compare resting Pd/Pa, FFR, and distal RFR values with and without hydrostatic pressure correction. Our main goal was to assess the influence of this correction on cut-off value-based decision-making for each physiological parameter. Data from patients enrolled in two centers of the READY registry (NCT04857762) were analyzed. Center 1 employed catheter and pressure sensor height differences defined from lateral angiographic projection for hydrostatic pressure correction, while Center 2 utilized average pressure differentials from published data. In Center 1, the height difference underlying the hydrostatic pressure correction did not differ significantly from the average values published in previous publication (-5.22±1.1cm for LAD, 2.44±1.1cm for CX, and 1.63±2.8cm for RCA). Consequently, FFR and distal RFR values corrected with average pressure differentials rarely yielded different cut-off-based characterizations compared to individually measured corrections (2.4%). A total of 42 measurements were evaluated in Center 1 (33 patients) and 40 measurements in Center 2 (40 patients). Stenoses were characterized using resting Pd/Pa (0.91 ± 0.05), FFR (0.80 ± 0.08), distal RFR (0.86 ± 0.09) and ΔRFR (0.07 ± 0.07) values. Regarding all the investigated vessels, statistically significant differences were observed in FFR (0.80 ± 0.08 vs 0.81 ± 0.08; p < 0.001), distal RFR (0.86 ± 0.09 vs 0.87 ± 0.09; p < 0.001), and ΔRFR (0.053 ± 0.04 vs 0.047 ± 0.04; p = 0.014) before and after correction. These changes after hydrostatic correction were driven dominantly by the LAD measurements being LAD stenoses constituted the majority of the cases (73.2%). Overall (n=82), hydrostatic pressure correction modified cut-off-based categorization in 24 (29.3%) cases for Pd/Pa, and 19 (23.2%) cases for both distal RFR and FFR measurements. Notably, ΔRFR assessment also changed in 22.2% of cases after correction. Among LAD stenoses (n=60), hydrostatic pressure correction altered cut-off-based characterization in 22 (36.7%), 19 (31.7%), and 17 (28.3%) cases of resting Pd/Pa, distal RFR, and FFR measurements, respectively. Hydrostatic pressure correction offers the potential to enhance the accuracy of intracoronary physiological measurements, especially for LAD stenoses. Our data suggest that the published average pressure differences of each coronary segment can be used for correction.Lateral view and delta RFRIndividual vs Average LAd correction