Clinical validity of the Japanese below-the-knee chronic total occlusion scoring system for the prediction of successful guidewire crossing

Abstract

ObjectiveTo validate the Japanese below-the-knee (J-BTK) chronic total occlusion (CTO) score for the prediction of successful guidewire crossing (S-GC) in angiographic evaluation. MethodsA prospective, multicenter, nonrandomized study examined 751 consecutive BTK CTOs in 497 patients treated with endovascular therapy in 16 Japanese medical centers from April 2021 to March 2022. The cohort was classified into 2 groups: an S-GC group and a failed guidewire crossing group. ResultsThe J-BTK CTO score, which assigned one point to “Blunt type at the proximal entry point,” one point to “Calcification at the proximal entry point,” one point to “Reference vessel diameter <2.0 mm,” one point to “CTO length ≥200 mm,” and two points to “No outflow of the target vessel,” was used to categorize BTK CTOs into 4 grades with varying probabilities of S-GC: grade A (J-BTK CTO score of 0 and 1), grade B (score of 2 and 3), grade C (score of 4 and 5), and grade D (score of 6). Rates of S-GC in each grade (grades A, B, C, and D) were 97.5%, 89.1%, 62.5%, and 27.3%, respectively. The area under the receiver-operating characteristic curve for S-GC was 0.8304. Although the previous J-BTK CTO study enrolled only de novo lesions, both de novo and restenotic lesions were evaluated in this study. De novo lesions have a lower chance of S-GC (odds ratio: 0.24, 95% confidence interval: 0.09-0.67) in the multivariate analysis, and the area under the receiver-operating characteristic curve of the modified J-BTK CTO score, which additionally assigned two points to “De novo lesion,” was 0.846. The modified J-BTK CTO score showed an appropriate calibration (Hosmer-Lemeshow P = .957). ConclusionsThe J-BTK CTO score and the modified J-BTK CTO score predict the probability of an S-GC of BTK CTOs and stratify the difficulty of endovascular therapy for BTK CTOs in angiographic evaluation.