Objective: To examine the incidence, predictors, and strategy-specific patterns of major in-hospital complications during contemporary chronic total occlusion percutaneous coronary intervention (CTO PCI) in a multicenter Turkish registry.

Methods: This retrospective analysis of a prospective multicenter registry included 2375 consecutive CTO PCI procedures performed from January 2020 to February 2026. The primary endpoint comprised death, myocardial infarction (MI), stroke, treatment-requiring coronary perforation, donor-vessel complication, emergency repeat percutaneous coronary intervention, or emergency coronary artery bypass grafting. Myocardial infarction and stroke were based on site-reported fields without central adjudication. Predictors were evaluated using logistic regression, with 500 bootstrap resamples for internal validation.

Results: Major complications occurred in 87 procedures (3.7%) and in-hospital death in 14 (0.6%). Event rates ranged from 1.3% in Japanese-Chronic Total Occlusion (J-CTO) 0-1 lesions to 7.3% in J-CTO ≥4 lesions and were 2.3% vs. 7.1% in planned antegrade-only vs. planned retrograde or hybrid procedures. With actual retrograde involvement, the complication rate was 8.1% vs. 2.2% without retrograde use (P < .001). Treatment-requiring perforation occurred in 52 procedures and donor-vessel complications in 22. The primary multiple logistic regression model yielded odds ratio (OR) of 1.02 per year for age (P = .042, 95% CI: 1.00-1.05); OR of 1.23 per 10 mm for CTO length (P = .002, 95% CI: 1.08-1.40); and OR of 1.92 for moderate or severe calcification (P = .005, 95% CI: 1.22-3.03). Model discrimination was area under the curve (AUC) of 0.668 (P < .001, 95% CI: 0.614-0.722); bootstrap optimism-corrected AUC = 0.643.

Conclusion: Major complications occurred in 3.7% of procedures, with rates varying across J-CTO strata and planned strategy groups. These findings may inform preprocedural counseling and procedural planning.