History of CTO Intervention and Benefits of CTO PCI

Currently, chronic total occlusion (CTO) is defined as the complete occlusion of coronary arteries with the duration of more than 3 months. Prevalence of CTO in patients who underwent coronary angiography ranged between approximately 20 and 50% [1, 2]. Total occlusion of coronary artery was firstly described in the 1940s. The role of coronary collateral circulation in chronic total occlusion was found in the late 1960s [3]. In the early period of percutaneous coronary intervention (PCI), PCI had been considered as contraindication in totally occluded vessel. In addition, the concept of CTO had not been established. A term of total coronary artery occlusion was widely used following categorization according to the estimated duration, including more than 12 weeks. The first successful PCI for total coronary occlusion lesion was published in 1984 [4] (Fig. 1.1). Holmes et al. published PCI result in total coronary artery occlusion in the same year [5]. However, all PCI results were failed in patients who had coronary occlusion estimated to be of more than 12 weeks’ duration in this study. In the early period (from late 1980s to early 1990s) of PCI for CTO lesion, the success rates were about 50–75% [6–8]. The first Korean report for the result of CTO intervention was published by Shim et al. in 1992 [9]. In this study, 7 of 24 patients had total occluded duration with longer than 4 weeks, and successful PCI rate was 42.9% in these lesions.