The utility of total lipid core burden index/maximal lipid core burden index ratio within the culprit plaque to predict filter-no reflow: insight from near-infrared spectroscopy with intravascular ultrasound

Filter-no reflow (FNR) is a phenomenon wherein flow improves after the retrieve of distal protection. Near-infrared spectroscopy with intravascular ultrasound (NIRS–IVUS) enables lipid detection. We evaluated the predictors of FNR during PCI using NIRS–IVUS. Thirty-two patients who underwent PCI using the Filtrap® for acute coronary syndrome (ACS) were enrolled. The culprit plaque (CP) was observed using NIRS–IVUS. Total lipid-core burden index (T-LCBI) and maximal LCBI over any 4-mm segment (max-LCBI4mm) within CP were evaluated. T-LCBI/max–LCBI4mm ratio within CP was calculated as an index of the extent of longitudinal lipid expansion. The attenuation grade (AG) and remodeling index (RI) in CP were analyzed. AG was scored based on the extent of attenuation occupying the number of quadrants. The patients were divided into FNR group (N = 8) and no-FNR group (N = 24). AG was significantly higher in FNR group than in no-FNR group (1.6 ± 0.6 vs. 0.9 ± 0.42, p = 0.01). RI in FNR group tended to be greater than in no-FNR group. T-LCBI/max–LCBI4mm ratio within the culprit plaque was significantly higher in FNR group than in no-FNR group (0.50 ± 0.10 vs. 0.33 ± 0.13, p 1.04 (odds ratio [OR] 18.4, 95% confidence interval [CI] 1.5–215.7, p = 0.02) and T-LCBI/max–LCBI4mm ratio > 0.42 (OR 14.4, 95% CI 1.2–176.8, p = 0.03) were independent predictors for the occurrence of FNR. The use of T-LCBI/max–LCBI4mm ratio within CP might be an effective marker to predict FNR during PCI in patients with ACS.