Coronary microvascular impairment may cause myocardial ischemia and systolic dysfunction in patients with idiopathic dilated cardiomyopathy (IDC).

The study included 41 patients with IDC and 33 healthy control subjects. Serum total antioxidant status (TAS), serum interleukin (IL)-6 levels, and tumor necrosis factor (TNF)-α levels were assayed and coronary flow reserve (CFR) was measured in all subjects via echocardiography.

High-sensitivity C-reactive protein (hsCRP) levels were significantly higher in patients with IDC than in the control group (3.42 ± 2.14 vs. 1.91± 1.40, p = 0.001). Serum TAS was statistically lower in patients with IDC than in controls (1.23 ± 0.16 vs. 1.77 ± 0.12, p < 0.001). CFR was statistically and significantly lower in the IDC group (2.10 ± 0.39 vs. 3.09 ± 0.49, p < 0.001). The IDC group was subsequently subdivided into two groups according to CFR values, as CFR ≥ 2 and CFR < 2. HsCRP (4.30 ± 2.42 vs. 2.58 ± 1.42, p = 0.01), TNF-α (16.67 ± 8.08 vs. 10.97 ± 1.63, p = 0.01), and IL-6 (7.54 ± 6.16 vs. 3.14 ± 1.10, p = 0.05) values were significantly higher in the CFR < 2 group compared with the higher CFR group. TAS (1.3 ± 0.16 vs. 1.14 ± 0.10, p < 0.001) was significantly lower in the CFR < 2 group. CFR correlated significantly with hsCRP, TAS, red cell distribution width (RDW), IL-6, and TNF-α.

Plasma proinflammatory cytokine levels are increased in patients with IDC. CFR was impaired as a reflection of impaired coronary microvascular dysfunction in association with increasing plasma proinflammatory cytokine levels and hsCRP levels.