Background: Cardio-pulmonary bypass may evoke
systemic inflammatory response in patients undergoing open-heart
surgery. Nevertheless, the occurrence and predictors of systemic
inflammatory response remain unknown. We sought to assess interleukin-6
(IL-6), hypoxia-induced factor (HIF) and CD73 levels before and after
open-heart surgery.

Methods and results: We
prospectively enrolled 284 consecutive patients undergoing open-heart
surgery between 2016–2017. Preoperative and first post-operative day
serum samples were analyzed for IL-6, HIF and CD73 levels. IL-6 levels
increased from 67.9 pg/mL to 1221 pg/mL while HIF and CD73 levels
decreased from 1.1 pg/mL to 0.93 pg/mL, and 8.2 pg/mL to 4.3 pg/mL,
respectively. Difference in IL-6 values were divided into two groups by
the median. Diabetics (OR 0.56, 95%-CI 0.32–0.98, p=0.04), patients on
statin treatment (OR 0.53, 95%-CI 0.31–0.93, p=0.03) and prior heart
failure (OR 0.37, 95%-CI 0.18–0.78, p=0.008) had lower risk of IL-6 rise
after cardiac surgery. High post-operative IL-6 values were associated
with new-onset post-operative atrial fibrillation (p=0.002).

Conclusions:
IL-6 levels rise significantly after cardiac surgery and are associated
with higher risk of new-onset post-operative atrial fibrillation.
Medical treatment for dyslipidemia, heart failure and diabetes appeared
to prevent excessive post-operative IL-6 rise.