Wu K, et al. - In this study with 155 patients who underwent retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI) through epicardial collaterals from August 2011 to December 2017 and were followed-up for a median of 2.5 years, researchers determined the predictors, treatment, and long-term outcomes seen relative to coronary perforation (CP). The Kaplan–Meier method was used to assess major adverse cardiac events (MACEs), and a multivariable Cox model was used to determine independent predictors of long-term MACE. Findings revealed CP was seen in 24 (15.5%) patients. The observed frequency of Ellis classes 1 or 2 and 3 were 41.7% and 58.3%, respectively. An increased risk of CP was observed in relation to retrograde CTO PCI through epicardial collaterals. The factors that independently predicted CP were renal dysfunction, right coronary artery (RCA) CTO, and Epi-CTO score ≥ 2. It is crucial to implement quick and appropriate management of CP. CP was not significantly related to adverse clinical outcomes.