Impact of coronary calcium patterns on procedural outcomes in CTO-PCI: a computed tomography-based multicenter study.

Coronary calcium significantly increases complexity in chronic total occlusion percutaneous coronary intervention (CTO-PCI). Coronary computed tomography angiography (CCTA) enables precise CTO assessment. However, no prior study has proposed a CCTA-based morphological classification of calcium patterns and assessed its procedural impact. To propose and validate a novel seven-point CCTA-derived classification of calcium morphology, ranging from "spot" (≤ 10% cross-sectional area, CSA) to "full moon" (100% CSA). We retrospectively included 167 patients undergoing CTO-PCI with prior CCTA. The primary endpoint was procedural failure. Secondary endpoints included coronary perforations, procedural and fluoroscopic time, and number of guidewires and balloons. A progressive, stepwise increase in procedural failure (from 6.2% in spot to 26.7% in full moon lesions; p = 0.007) and coronary perforation rates (from 3.1% in spot to 13.3% in full moon lesions; p = 0.03) was observed across the seven identified calcium patterns. In multivariable analysis, calcium severity was independently associated with procedural failure (OR 1.2 per step; 95% CI 1.01-1.52; p = 0.04). Increasing calcium severity was also independently associated with procedural time (B =  + 4.7 min/step; p = 0.03), fluoroscopic time (B =  + 2.2 min/step; p = 0.04), number of guidewires (B =  + 0.30/step; p = 0.03) and balloons (B =  + 0.31/step; p = 0.005). Full-scale progression from "spot" to "full moon" corresponded to + 33 min increase in procedural and + 14 min in fluoroscopic time. A novel CCTA-based calcium classification showed a strong, independent association with procedural failure and complexity. Its reproducibility and integration potential make it a valuable tool for enhancing planning and safety in CTO-PCI.