Percutaneous coronary intervention (PCI) for chronic total occlusions (CTOs) has a lower success rate than PCI for non-CTO lesions. We sought to determine trends in the treatment of CTOs within the current interventional era. Using 4 sequential recruitment waves of the National Heart, Lung, and Blood Institute Dynamic Registry, we assessed the relative prevalence and success rates in treating CTO (n=371) versus non-CTO (n=4,802) lesions over a 7-year period (1997 to 2004). Characteristics of attempted lesions and factors associated with PCI outcome were evaluated. CTO lesion attempts decreased by 41% over time, from 9.6% (1997 to 1998) to 5.7% (2004, p<0.0001 for trend). More contemporary CTO lesions were longer (22.4 vs 17.0 mm, p=0.006 for trend), had thrombus less often (21.3% vs 35.4%, p=0.03 for trend), and were more often treated with stents (69.8% vs 45.4% p=0.02). The rate of successful intervention for CTO lesions decreased nonsignificantly during this time, from 79.7% to 71.4% (p=0.18). Using multivariable analysis, female gender (adjusted odds ratio 0.42, 95% confidence interval 0.20 to 0.88, p=0.02), and thrombus (adjusted odds ratio 0.31, 95% confidence interval 0.15 to 0.61, p=0.0008) were associated with higher success rates, whereas the presence of severe noncardiac disease (adjusted odds ratio 1.91, 95% confidence interval 1.05 to 3.45, p=0.03) was associated with a higher risk for PCI failure. Recruitment wave and patient age were not independently related to lesion success. In conclusion, during the PCI period of 1997 to 2004, CTO lesions were attempted less frequently and success rates did not increase, indicating a need for new operator techniques or device technologies to treat this important lesion subset by a percutaneous approach.