Validation of the BCIS CHIP Score in chronic total occlusion percutaneous coronary intervention

Background: The complex high-risk indicated percutaneous coronary intervention (CHIP) score is a tool developed using the British Cardiovascular Intervention Society (BCIS) database to define CHIP cases and predict in-hospital major adverse cardiac or cerebrovascular events (MACCE). Aim: To assess the validity of the CHIP score in chronic total occlusion (CTO) percutaneous coronary intervention (PCI). Methods: We evaluated the performance of the CHIP score on 8341 CTO PCIs from the Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS-CTO) performed at 44 centers between 2012 and 2023. Results: In our cohort, 7.8% (n = 647) of patients had a CHIP score of 0, 50.2% (n = 4192) had a CHIP score of 1–2, 26.2% (n = 2187) had a CHIP score of 3–4, 11.7% (n = 972) had a CHIP score of 5–6, 3.3% (n = 276) had a CHIP score of 7–8, and 0.8% (n = 67) had a CHIP score of 9+. The incidence of MACCE for a CHIP score of 0 was 0.6%, reaching as high as 8.7% for a CHIP score of 9+, confirming that a higher CHIP score is associated with a higher risk of MACCE. The estimated increase in the risk of MACCE per one score unit increase was 100% (95% confidence interval [CI]: 65%–141%). The AUC of the CHIP score model for predicting MACCE in our cohort was 0.63 (95% CI: 0.58–0.67). There was a positive correlation between the CHIP score and the PROGRESS-CTO MACE score (Spearman's correlation: 0.37; 95% CI: 0.35–0.39; p < 0.001). Conclusions: The CHIP score has modest predictive capacity for MACCE in CTO PCI.