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It is unclear whether changes in plasma levels of inflammatory markers could explain the link between ischemia and slow coronary flow (SCF). We aimed to evaluate the plasma levels of high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, and myeloperoxidase (MPO) during myocardial perfusion imaging (MPI) in SCF patients.
Study population consisted of 53 SCF patients and 30 controls. Coronary flow rates were documented by TIMI frame count (TFC). Plasma levels of hsCRP, IL-6, MPO, and MPI were obtained in all participants.
The hsCRP, IL-6 and MPO levels of SCF patients were higher than controls (hsCRP: 4.7 ± 2.5 vs. 1.7 ± 1.1 mg/L, p<0.001; IL-6: 8.2 ± 4.3 vs. 5.2 ± 2.1 pg/mL, p<0.001; and MPO: 75.9 ± 59.6 vs. 24.3 ± 16.7 ng/mL, p<0.001). Twenty-one SCF patients exhibited myocardial perfusion defect (MPD) on MPI. In SCF patients, the highest hsCRP, IL-6 and MPO were observed in patients with both MPD and three-vessel slow flow. Mean TFCs were positively correlated with plasma levels of hsCRP (r=0.424, p=0.002), IL-6 (r=0.367, p=0.007), MPO (r=0.430, p=0.001), and reversibility score (r=0.671, p<0.001) in SCF patients. HsCRP and MPO were the independent variables, which predicted positive MPI-results (hsCRP: OR, 2.176; 95% CI, 1.200 to 3.943; p=0.010, MPO: OR, 1.026; 95% CI, 1.007 to 1.046; p=0.008).
Inflammation might play a crucial role in both the pathogenesis and development of ischemia in SCF. Association of increased levels of inflammatory markers and ischemia suggests that endothelial inflammation might be largely responsible for clinical presentation. New combined treatment regimens should target at endothelial activation and inflammation in SCF.