In a registry analysis of 8,004 consecutive patients presenting for diagnostic catheterization at a single institution from 1990 to 2000, chronic total occlusion (CTO) was found in 52% of patients with significant (> or = 70% diameter stenosis) coronary artery disease. Peripheral vascular disease was the strongest clinical predictor of the presence of a CTO. In a multivariate analysis, CTO was the strongest predictor against the selection of percutaneous coronary intervention (PCI) as a treatment strategy, indicating that efforts to improve the success rate of PCI in CTO may have a significant impact on management of coronary disease.