Impact of ramus coronary artery on computed tomography derived fractional flow reserve (FFR_CT) in no apparent coronary artery disease

Abstract

Background The ramus artery contributes to the development of turbulence, which may influence computed tomography (CT) derived fractional flow reserve (FFRCT) even without coronary artery disease (CAD). The relationship between ramus‐induced turbulence and FFRCT is unclear. Method and Results A total of 120 patients with <20% coronary stenosis assessed by both FFRCT and invasive coronary angiography were evaluated. The patients were divided into three groups: absent‐ramus (n = 72), small‐ramus that could not be analyzed by FFRCT (n = 18), and large‐ramus that could be analyzed by FFRCT (n = 30). FFRCT measurements were performed at the proximal and distal segments of the left anterior descending (LAD), left circumflex (LCX), and ramus artery. With absent‐ramus and small‐absent ramus groups, FFRCT was measured at the distal end of the left main trunk at the same level for the proximal segments of the LAD and LCX. In absent‐ramus group, proximal FFRCT showed no significant differences between three vessels (LAD = .96 ± .02; MID = .97 ± .02; LCX = .97 ± .02). However, in small and large‐ramus groups, proximal FFRCT was significantly higher in the ramus artery than LAD and LCX (small‐ramus, LAD = .95 ± .03, Ramus = .97 ± .02, LCX = .95 ± .03; large‐ramus: LAD = .95 ± .03, Ramus = .98 ± .01; LCX = .96 ± .03; p < .05). A large ramus was associated with a higher prevalence of a distal FFRCT ≤.80 (odds ratio 7.0, 95% CI 1.2–40.1, p = .03). A proximal ramus diameter predicted distal FFRCT ≤.80 (cut‐off 2.1 mm, AUC .76, sensitivity 100%, specificity 52%, 95% CI .61–.90). Conclusions The presence of a large‐ramus artery may cause an FFRCT decline in no apparent CAD.

Impact of vessel morphology on CT-derived fractional-flow-reserve in non-obstructive coronary artery disease in right coronary artery

“…This finding may be related to energy loss due to turbulence by the bifurcation from the left main trunk to LAD and LCX, or splitting into large branches such as diagonal branch, obtuse marginal branch, or posterior descending branch. Our previous study on the ramus artery demonstrated that the presence of a large ramus artery yields energy loss due to turbulence around the bifurcation angle, resulting in distal FFR CT decline in both LAD and LCX [ 23 , 24 ]. Turbulent eddies generated by the presence of large branches could contribute to energy loss, resulting in impact on FFR CT hemodynamics.…”

Impact of Advanced Extravascular Calcified Plaque on the Assessment of Coronary Stenosis Severity

“…[3][4][5] FFR CT (HeartFlow Inc., Redwood City, California, USA) was calculated based on a threedimensional anatomical model synthesized from CCTA data. [3][4][5][6][7][8] The vessel lengths of the proximal portion, stenotic lesion, and distal portion were 11 mm, 19 mm, and 96 mm, respectively (Figures 1A-B). The proximal and distal portions contained mild IAP, whereas the stenotic lesion was characterized by abundant IAP and CP (Figures 1C-J and 2), particularly in the middle part of the stenotic lesion surrounded by CP (Figure 1F).…”