Background: The retrograde approach improves the procedural success rate of chronic total occlusion percutaneous coronary interventions (CTO-PCIs). However, it remains unclear whether the primary retrograde approach (PRA) offers benefits in terms of procedural success and burden/resource use in challenging cases. Therefore, we compared efficacy between the primary antegrade approach (PAA) and PRA in complex CTO-PCIs.

Methods and Results: This single-center retrospective cohort study included all patients undergoing coronary CTO-PCI attempted by experienced high-volume operators between January 2016 and July 2023. The difficulty of the antegrade approach was determined using the Japanese CTO score, and the feasibility of interventional collaterals was determined using the collateral channel score. In 698 patients undergoing CTO-PCI, the overall technical and initial guidewire success rates were 91.4% and 83.8%, respectively. Of 380 patients with a Japanese CTO score≥ 3 and a collateral channel score≥ 2, PAA and PRA were performed in 161 (42.4%) and 219 (57.6%) patients, respectively. Initial guidewire success was higher with PRA than PAA (88.1% vs. 78.9%; P= 0.01), and bail-out success was higher for a retrograde than antegrade approach (91.2% vs. 56%; P= 0.0019). PRA was associated with longer guidewire crossing time, longer fluoroscopy time, and greater contrast use.

Conclusions: In patients with challenging CTO, poor antegrade conditions, and feasible interventional collaterals, PRA achieved higher initial guidewire success at the expense of higher procedural burden/resource use.