OBJECTIVE: To examine the association between the C-reactive protein-triglyceride glucose (CTI) index and coronary collateral circulation (CCC) in patients with chronic total occlusion (CTO), and to assess its predictive performance for poor CCC compared to traditional biomarkers, by developing an accessible risk stratification tool based on routine clinical data, we seek to facilitate early identification of high-risk patients and inform targeted clinical management. METHODS: This retrospective study analyzed 545 patients, classifying CCC using the Rentrop score. The CTI index was calculated from high-sensitivity C-reactive protein (hs-CRP), triglycerides, and fasting plasma glucose. The association between CTI (as a continuous variable) and poor CCC was assessed using multivariate logistic regression, with results presented as odds ratios (OR) and 95% confidence intervals (CI). Model performance was evaluated by the area under the receiver operating characteristic curve (AUC). Restricted cubic spline and subgroup analyses were performed to examine the dose-response relationship and the consistency of the association, respectively. RESULTS: Among the 545 CTO patients, 167 (30.6%) developed poor CCC. The poor CCC group demonstrated significantly higher levels of CTI, inflammatory markers, and cardiometabolic risk indicators (all P < 0.001). Multivariable logistic regression revealed the CTI index as an independent risk factor for poor CCC (OR = 2.63, 95% CI [1.75-4.10], P < 0.001). The receiver operating characteristic (ROC) analysis showed the CTI index (AUC = 0.679, 95% CI [0.632-0.726]; P < 0.001) had comparable predictive ability to the triglyceride-glucose (TyG) index, atherogenic index of plasma (AIP), and neutrophil to high-density lipoprotein ratio (NHR). Restricted cubic spline analysis indicated a significant linear dose-response relationship between CTI and poor CCC risk (P-overall <0.001). Subgroup analyses confirmed the consistent association of CTI with poor CCC across various patient populations (P for interaction >0.05). CONCLUSION: The CTI index demonstrated a significant and independent association with impaired coronary collateral circulation in CTO patients, exhibiting modest predictive value (AUC = 0.679) compared to traditional biomarkers. This readily accessible index may serve as a complementary tool for early risk stratification. Future multi-center prospective studies are warranted to validate its clinical utility and explore underlying mechanisms.