Microvascular complications are associated with coronary collateralization in type 2 diabetes and chronic occlusion

Context: Coronary collateral (CC) vessel development appears to be protective with regard to adverse cardiovascular events and survival in patients with coronary chronic total occlusion (CTO). The influence of type 2 diabetes mellitus (T2DM) on CC growth has been controversial. In particular, the role of diabetic microvascular complications (DMC) in determining coronary collateralization has not been elucidated. Objective: To investigate whether patients with DMC presented differences in CC vessels presence and grading as compared to those without DMC. Methods: We conducted a single-center observational study, including consecutive T2DM patients without previous cardiovascular history, undergoing a clinically indicated coronary angiography for chronic coronary syndrome (CCS) and angiographic evidence of at least one CTO. Patients were subdivided into two study groups according to the presence/absence of at least one of DMC (either neuropathy, nephropathy of retinopathy). The presence and the grading of angiographically visible CC development from the patent vessels to the occluded artery were assessed using the classification developed by Rentrop et al. Results: We enrolled in total 157 patients (mean age 68.6±9.8 years; 120 [76.4%] men). Patients with DMC (75 [47.8%]) had a higher prevalence of CC (69 [92.0%] vs. 62 [75.6%], p = 0.006) and high-grade CC (55 (73.3%) vs. 39 (47.6%), p = 0.001] compared to those without and a positive association between the number of DMC in each patient and the prevalence of high-grade CC was found. Conclusions: Among T2DM patients with coronary CTO, the presence of DMC was associated with a high CC development.