The investigators conducted a retrospective, single-center observational registry upon which one novel scoring system was formed and evaluated for their accuracy in predicting technical success. The investigators reviewed the clinical and angiographic records of 432 patients with 459 CTO lesions who underwent percutaneous recanalization attempts recruited between January 2012 and November 2023. The investigators aims to develop and validate a novel scoring system for predicting CTO-PCI success.

Chronic total occlusions (CTO) accounting for about 15-20% of coronary artery lesions can be challenging and only 10-15% of patients undergo successful percutaneous coronary intervention (PCI) .Thanks to the technological and device advances, the marked improvement of PCI success rates could be seen. However, in contrast to non-CTO lesions, these procedures are accompanied by longer procedure time, contrast and radiation burden, and higher complication rates. The possibility to predict which CTOs are more likely to be treated successfully is still of utmost importance for patient selection. Several scores have been proposed to predict the procedural success rate, such as J-CTO, CL-Score, Progress-Score et al , J-CTO is widely accepted. But Karatasakis et al.showed that these scores performed moderately in predicting technical outcome, while ignoring many factors such as stumpless lesion which may exert an influence on the procedural success. The investigators aims to develop and validate a novel scoring system for predicting CTO-PCI success.

Inclusion Criteria:

1. complete occlusion of the coronary artery, confirmed by coronary angiography with TIMI flow grade 0, and occlusion for ≥3 months;
2. presence of angina or angina-equivalent symptoms ; undergo coronary intervention;

Exclusion Criteria:

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patients with CTO lesions who underwent percutaneous recanalization attempts recruited between January 2012 and November 2023