Below-the-knee (BTK) chronic total occlusion (CTO) in patients with chronic limb-threatening ischemia (CLTI) remains one of the most challenging targets for endovascular therapy. The Crosser catheter, initially developed as a CTO crossing device, has often been used as a flossing device in balloon-uncrossable lesions. The newly introduced Crosser iQ, available in Japan since September 2024, is designed to enhance crossing efficiency and safety.

This retrospective study included 60 CLTI patients treated for BTK CTO with the Crosser iQ between October 2024 and October 2025. Fifty cases using the device for primary crossing were analyzed as the main cohort, and 10 adjunctive cases as an exploratory subgroup. The primary endpoint was technical success, defined as successful passage into the distal true lumen. Secondary endpoints included procedural success, complications (perforation, dissection, slow-flow, distal embolism, tip-related events), and procedure time.

Technical success was achieved in 90% of cases. No significant differences were found across PACSS grades or lesion length. Only one case of slow-flow occurred, with no major complications. Procedural success was favorable, and procedure time tended to be shorter compared with conventional BTK CTO interventions.

The Crosser iQ-based DART-iQ BTK Technique demonstrated high technical success, acceptable safety, and potential for procedural efficiency improvement in CLTI patients with BTK CTO.