HMOX1 and coronary atherosclerosis: The present study, performed in a well characterized European population of patients with CCS, showed that patients with higher levels of circulating HO-1, a well-known marker of oxidative stress, have a specific clinical phenotype characterized by lower lipid levels, a more diffuse mainly non-obstructive and calcified coronary atherosclerosis, and a higher prevalence of functional ischemia, despite a similar frequency of obstructive disease.