Increased plasma high-sensitivity C-reactive protein and myeloperoxidase levels may predict ischemia during myocardial perfusion imaging in slow coronary flow.

Background And Aims: It is unclear whether changes in plasma levels of inflammatory markers could explain the link between ischemia and slow coronary flow (SCF). The aim of the study was 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.

Methods: The 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.

Results: 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 levels 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, 1.200-3.943; p = 0.010, MPO: OR, 1.026; 95% CI, 1.007-1.046; p = 0.008).

Conclusions: Inflammation may 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 may be largely responsible for clinical presentation. New combined treatment regimens should target endothelial activation and inflammation in SCF.