AbstractBackgroundDonor vessel injury is a potentially life‐threatening complication of chronic total occlusion (CTO) percutaneous coronary intervention (PCI).AimsOur goal was to examine the incidence, mechanisms, treatment, and outcomes of patients with donor vessel injury in a large multicenter CTO PCI registry.MethodsWe analyzed the baseline clinical and angiographic characteristics, and procedural outcomes of 12,349 CTO PCIs performed between 2012 and 2022 at 44 centers.ResultsThe incidence of donor vessel injury was 0.35% (n = 43). The baseline clinical characteristics of patients with and without donor vessel injury were similar. Cases complicated by donor vessel injury were more complex with higher Japanese CTO score (2.9 ± 1.1 vs. 2.4 ± 1.3; p = 0.004) and lower procedural success rate (69.8% vs. 85.2%; p = 0.004). The retrograde approach was used more commonly in donor vessel injury cases (68.9% vs. 30.9%; p < 0.001). Most (53.5%) donor vessel injuries were guide catheter‐induced, whereas 20.9% were due to donor vessel thrombosis. Of the 43 patients with donor vessel injury, 36 (83.7%) were treated with stenting and seven (16.3%) received a left ventricular assist device. The incidence of major adverse cardiovascular events (MACEs) was significantly higher in cases with donor vessel injury (23.3% vs. 2.0%; p < 0.001). Of the 43 patients with donor vessel injury, five patients (11.6%) experienced acute myocardial infarction and four patients (9.3%) died.ConclusionsDonor vessel injury, occurred in 0.35% of CTO PCIs performed by experienced operators, was mainly due to guide catheter‐induced dissection or thrombosis and was associated with lower procedural success and higher MACE.