Impact of height difference between coronary ostium and location of intracoronary pressure sensor on fractional flow reserve measurements

Abstract

Background During fractional flow reserve (FFR) measurements, distal coronary pressure (Pd) can be influenced by hydrostatic pressure changes resulting from the height difference (HD) between the coronary ostium and the location of the distal pressure sensor. Aims We investigated the effect of aortocoronary HD on the FFR measurements in each coronary artery. Methods In this retrospective cohort study, we analyzed 257 patients who underwent FFR measurements and coronary computed tomography (CCTA) within a year. Using CCTA, we measured HD as the vertical distance between the coronary ostium and a matched point of the distal coronary pressure sensor identified on coronary angiography. Results The location of the Pd sensor was higher than the coronary ostium in the left anterior descending artery (LAD) (-4.64 ± 1.15 cm) and lower than the coronary ostium in the left circumflex artery (LCX) (2.54 ± 1.05 cm) and right coronary artery (RCA) (2.03 ± 1.28 cm). The corrected FFR values by HD were higher in the LAD (0.78 ± 0.09 to 0.82 ± 0.09, P<0.01) and lower in the LCX and RCA than the original FFR values (0.87 ± 0.07 to 0.85 ± 0.08, P<0.01; 0.87 ± 0.10 to 0.86 ± 0.10, P<0.01, respectively). Using an FFR cut-off value of 0.8, the concordance rates between the FFR and corrected FFR values were 77.8%, 95.2%, and 100% in the LAD, LCX, and RCA, respectively. Conclusion HD between the coronary ostium and the distal coronary pressure sensor may affect FFR measurements and FFR-guided treatment decisions for coronary artery disease.

The Effect of Hydrostatic Pressure on Coronary Flow and Pressure-Based Indices of Coronary Stenosis Severity

“…Harle et al used a dynamic flow simulator to perform in vitro measurements and showed a correlation between absolute pressure differences and coronary height differences [ 8 ]. Other studies used recorded pressure measurements and compared the actual pressure ratios with pressure ratios corrected for hydrostatic pressure showing a reclassification of 12–13% for FFR and 20–27% for non-hyperaemic pressure ratios [ 13 , 14 , 15 ]. One study used an animal model and took FFR measurements during various height differences between the guide catheter tip and the distal pressure wire sensor produced by body rotation (20° to the right and 25° to the left) with or without vertical inclination (10° above and 10° below) of the catheterisation bed [ 12 ].…”

“…In clinical practice, this hydrostatic pressure effect is ignored, as the actual pressure gradient is usually small (<5 mmHg) [ 9 ]. Nevertheless, recent studies have suggested that the hydrostatic pressure gradient influences significantly pressure-based physiological indices [ 7 , 10 , 11 , 12 , 13 , 14 , 15 ], and as such the quantification of the hydrostatic impact on clinical practice remains poorly understood.…”