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

ABSTRACT

OBJECTIVE: To 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. METHODS: A 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. RESULTS: The 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). CONCLUSIONS: The 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.