Impact of “Full Moon” calcification assessed by preprocedural cardiac computed tomography on guidewire crossing in percutaneous coronary intervention for chronic total occlusion: FULL MOON registry

Background Severe coronary calcification remains a major determinant of procedural difficulty and failure in chronic total occlusion percutaneous coronary intervention (CTO-PCI). Among calcification patterns, “full moon”–like calcification on cardiac computed tomography (CT) has been considered particularly unfavourable; however, its assessment is susceptible to calcium blooming artefacts, and prior evaluations have largely relied on limited cross-sectional analysis. Purpose This study aimed to investigate the impact of more accurately classified CT-derived full moon–like calcification on procedural characteristics and clinical outcomes of CTO-PCI. Methods This registry was a retrospective, multicentre observational study conducted at 42 centres in Japan. Patients who underwent CTO-PCI between April 2022 and August 2024 and had pre-procedural contrast-enhanced cardiac CT within 1 year were screened. Calcification morphology was reassessed using window level/window width adjustment (400/1500) to minimise blooming artefacts, combined with three-dimensional CT analysis. “True full moon” calcification was defined as circumferential luminal occupation persisting even after window adjustment (Figure 1A). The primary endpoint was guidewire crossing success. Results A total of 91 CTO lesions were included. Guidewire crossing success was significantly lower in lesions with “True full moon” calcification compared to “Pseudo full moon” calcification (47.8% vs 83.8%; p=0.002) (Figure 1B). Multivariable logistic regression identified “true full moon” morphology and calcification length ≥15 mm as strong predictors of guidewire crossing failure. When both factors were present, guidewire crossing success was markedly reduced. Incorporation of these CT-based parameters significantly improved the prediction of procedural failure beyond the performance of established CTO complexity scores, including J-CTO (Multicentre CTO Registry of Japan), KCCT (Korean Multicentre CTO CT Registry), and CT-RECTOR (Computed Tomography Registry of Chronic Total Occlusion Revascularisation) scores (Figure 2). Conclusion PCI for CTO lesions with “True full moon” calcification is associated with a significantly lower guidewire crossing success rate. CT-derived true full moon morphology and longitudinal calcification extent provide incremental prognostic value and may enhance pre-procedural risk stratification and procedural planning for CTO-PCI.