Coronary artery perforation is one of the most feared complications of chronic total occlusion (CTO) percutaneous coronary intervention (PCI), as it can lead to pericardial effusion and tamponade [1] . The OPEN-CLEAN (Outcomes, Patient health status, and Efficiency IN CTO hybrid procedures-CABG, Length of occlusion, EF < 50%, Age, severe calcificatioN) perforation score [2] is computed from 5 parameters: prior coronary artery bypass graft (CABG), occlusion length, ejection fraction (EF), age and severe calcification. The score range is 0 to 7 and higher score is associated with higher risk of perforation. We evaluated the performance of the OPEN-CLEAN score in the PROGRESS-CTO (PROspective Global REgiStry for the Study of Chronic Total Occlusion Intervention; Clinicaltrials.gov identifier: NCT02061436 ) registry.