AbstractBackgroundThe impact of preprocedural anemia on the outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study.MethodsWe examined the clinical and angiographic characteristics and procedural outcomes of 8633 CTO PCIs performed at 39 US and non‐US centers between 2012 and 2023. Anemia was defined as a hemoglobin level of <13 g/dL in men and <12 g/dL in women.ResultsAnemia was present in 1652 (19%) patients undergoing CTO PCI. Anemic patients had a higher incidence of comorbidities, such as diabetes mellitus, hypertension, dyslipidemia, heart failure, cerebrovascular disease, and peripheral arterial disease. CTOs in anemic patients were more likely to have complex angiographic characteristics, including smaller diameter, longer length, moderate to severe calcification, and moderate to severe proximal tortuosity. Anemic patients required longer procedure (119 vs. 107 min; p < 0.001) and fluoroscopy (45 vs. 40 min; p < 0.001) times but received similar contrast volumes. Technical success was similar between the two groups. In‐hospital major adverse cardiac events (MACE) rates were higher in patients with anemia; however, this association was no longer significant after adjusting for confounding factors. Baseline anemia was independently associated with follow‐up MACE (adjusted hazard ratio [HR]: 1.63; 95% confidence interval [CI]: 1.07–2.49; p = 0.023) and all‐cause mortality (adjusted HR: 3.03; 95% CI: 1.41–6.49; p = 0.004).ConclusionsPreprocedural anemia is associated with more comorbidities, higher lesion complexity, longer procedure times, and higher follow‐up MACE and mortality after CTO PCI.