C-Reactive protein kinetics after cardiac surgery: A retrospective multicenter study.

Background: Recognition of postoperative infection after cardiac surgery is challenging. Biomarkers may be very useful to recognize infection at early stage, but the literature is controversial. Methods: We conducted a retrospective study at two large University Hospitals, including adult patients undergoing cardiac surgery (excluding those with preoperative infections, cirrhotic or immunocompromised). We evaluated the kinetics of C-Reactive Protein (CRP) and White Cell Count (WCC) during the first postoperative week. Primary outcomes were CRP and WCC changes according to the development of postoperative infection. In order to evaluate the influence of cardiopulmonary bypass on biomarker kinetics, we also studied CRP and WCC changes in patients without postoperative infection and undergoing on- vs off-pump coronary-artery bypass grafting. Results: Among 429 included, 45 patients (10.5%) had evidence of postoperative infection. Patients with postoperative infection had higher CRP and WCC values than those without infection, with between-groups difference becoming significant from postoperative day 2 for CRP (120.6 ± 3.6 vs. 134.6 ± 7.9, P < 0.01), and from postoperative day 3 for WCC (10.5 ± 0.5 vs. 9.9 ± 0.2, P = 0.02). Over the postoperative period, CRP and WCC showed significant within-group changes regardless of development of postoperative infection (P < 0.001 for both). We found no differences in CRP and WCC kinetics between patients undergoing on- vs off-pump procedure. Conclusions: During the first week after cardiac surgery, CRP increases one day earlier than WCC in patients developing postoperative infections, with such difference becoming significant on the second postoperative day. In not infected patients, use of cardiopulmonary bypass does not influence CRP and WCC kinetics.