In-stent versus de novo chronic total occlusion PCI: Similar acute success but distinct procedural and treatment patterns.

BACKGROUND: Whether in-stent chronic total occlusion (ISR-CTO) reflects lower CTO percutaneous coronary intervention (PCI) efficacy or a distinct procedural profile remains uncertain. AIMS: To compare acute outcomes, strategy, and treatment pattern between ISR-CTO and de novo CTO. METHODS: We performed a retrospective procedure-level analysis of a prospectively maintained three-center CTO PCI registry from Türkiye, including consecutive procedures between January 2019 and February 2026. The primary endpoint was procedural success, defined as technical success without in-hospital major procedural complications. Technical success was final TIMI 3 flow with residual stenosis < 30%. Major procedural complications included death, stroke, emergency repeat PCI or coronary artery bypass grafting (CABG), donor-vessel complication, and coronary or collateral perforation requiring active treatment. Multivariable logistic regression and prespecified sensitivity analyses were performed. RESULTS: Among 2375 CTO PCI procedures, 296 (12.5%) involved ISR-CTO. Technical success was 92.9% in ISR-CTO and 91.7% in de novo CTO (P = 0.49). Procedural success was 90.2% and 89.0% (P = 0.55), and major procedural complications were similar (3.4% vs. 3.9%, P = 0.66). After adjustment, ISR-CTO was not associated with lower technical success (OR, 1.26; 95% CI, 0.77-2.05), lower procedural success (OR, 1.20; 95% CI, 0.79-1.83), or higher complication risk (OR, 0.84; 95% CI, 0.43-1.66). ISR-CTO was associated with less actual retrograde involvement, greater IVUS/DCB use, and a lower observed DES implantation rate. CONCLUSIONS: ISR-CTO showed acute procedural results comparable to de novo CTO in this selected multicenter cohort. Its main differences were procedural and treatment-related, including less actual retrograde involvement and different IVUS/DCB/DES use.