Background: The exact role of individual inflammatory factor in heart failure with reduced ejection fraction (HFrEF) remains elusive. The study aimed to evaluate three monocyte subsets (classical-CD14++CD16-, intermediate-CD14++CD16+, and nonclassical-CD14+CD16++) in HFrEF patients and to assess the effect of the cardiac resynchronization therapy (CRT) on the changes in monocyte compartment.
Methods: The study included 85 patients with stable HFrEF. Twenty-five of them underwent CRT device implantation with subsequent 6-month assessment. The control group consisted of 23 volunteers without HFrEF.
Results: The analysis revealed that frequencies of non-classical-CD14+CD16++ monocytes were lower in HFrEF patients compared to the control group (6.98 IQR: 4.95-8.65 vs. 8.37 IQR: 6.47-9.94; p = 0.021), while CD14++CD16+ and CD14++CD16- did not differ. The analysis effect of CRT on the frequency of analysed monocyte subsets 6 months after CRT device implantation showed a significant increase in CD14+CD16++ (from 7 IQR: 4.5-8.4 to 7.9 IQR: 6.5-9.5; p = 0.042) and CD14++CD16+ (from 5.1 IQR: 3.7-6.5 to 6.8 IQR: 5.4-7.4; p = 0.017) monocytes, while the frequency of steady-state CD14++CD16- monocytes was decreased (from 81.4 IQR: 78-86.2 to 78.2 IQR: 76.1-81.7; p = 0.003).
Conclusions: HFrEF patients present altered monocyte composition. CRT-related changes in the monocyte compartment achieve levels observed in controls without HFrEF.
Keywords: cardiac resynchronization therapy; chemokines; heart failure; iron homeostasis; monocytes.