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

Abstract

AbstractBackgroundThe 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 ResultsA 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).ConclusionsThe presence of a large‐ramus artery may cause an FFRCT decline in no apparent CAD.