Background Monocytes play an integral role in the development of atherosclerosis. Specific monocyte subsets have been associated with excess cardiovascular events in different patient populations and highlighted as a potential therapeutic target.

Objective To compare blood monocyte subsets in patients with focal coronary artery disease (CAD) and diffuse CAD.

Methods Three monocyte subsets (CD14⁺+CD16-CCR2+ [classical, Mon 1], CD14⁺+CD16⁺CCR2+ [intermediate, Mon 2] and CD14⁺CD16⁺+CCR2- [non-classical, Mon 3]) and their aggregates with platelets (monocyte-platelet aggregates, MPAs) were quantified by flow cytometry in 71 CAD patients (subdivided into a group with diffuse CAD [n = 50] and a group with focal CAD [n = 21] based on angiographic coronary artery morphology) and 39 age, sex and risk factor matched controls with normal coronary arteries assessed either invasively or non-invasively using computed tomography coronary angiography (CTCA).

Results The clinical characteristics of each group are shown in Table 1. Patients with diffuse CAD had a significantly higher proportion of Mon 2 than patients with focal disease (p = 0.02) or normal coronary arteries (p = 0.03) (Table 2). MPA associated with Mon 2 was also significantly higher in the diffuse CAD group (p < 0.001). There was no difference in the levels of Mon 1 or Mon 3 between the groups (p = 0.84 and p = 0.51, respectively). There was no difference in MPA associated with Mon 1 between diffuse or focal CAD (p = 0.30) but these MPA were significantly higher in patients with diffuse CAD compared to normal controls (p = 0.02). There was no difference in MPA associated with Mon 3 between the groups (p = 0.17).

Conclusion Patients with diffuse CAD have higher peripheral blood levels of Mon 2 and MPA associated with Mon 2 than patients with focal CAD. Our data support the notion that Mon 2 is related to worse CAD morphology.