what is a cto procedure
âChronic Total Occlusion Intervention. Chronic total occlusion (CTO) is a complete blockage of a coronary artery that has been in place for 30 days or longer. CTOs are very common, occurring in 15 to 20 percent of patients with significant coronary artery disease. The condition can cause severe angina (chest pain) and lead to a lower quality of life.