Albumin and Cardioprotection in On-Pump Cardiac Surgery-A Post Hoc Analysis of a Randomized Trial

Objectives: To study the quantitative potency of plasma albumin on cardioprotection in terms of creatinine kinase-myocardial band mass (CK-MBm) in on-pump cardiac surgery.Design: Post hoc analysis of a double-blinded randomized clinical trial.Setting: Single-center study in the Helsinki University Hospital.Participants: A total of 1,386 adult on-pump cardiac surgical patients.Intervention: Administration of 4% albumin (n = 693) or Ringers acetate (n = 693) for cardiopulmonary bypass priming and volume replacement intraoperatively and postoperatively during the first 24 hours.Measurements and main results: Albumin concentration was measured preoperatively and intraoperatively (after protamine administration), and CK-MBm on the first postoperative morning. Multivariate linear regression analyses were measured in the whole cohort and the Ringer group. Plasma albumin concentration did not differ between the groups preoperatively (Ringer v albumin: 38.3 +/- 5.0 g/L v 38.6 +/- 4.5 g/L; p = 0.171) but differed intraoperatively (29.5 +/- 5.2 g/L v 41.5 +/- 6.0 g/L; p < 0.001). Creatinine kinase-myocardial band mass was higher in the Ringer (32.0 +/- 34.8 mu g/L) than in the albumin group (24.3 +/- 33.0 mu g/L) (p < 0.001). Aortic cross-clamping time associated with CK-MBm in the whole cohort (standardized beta = 0.376 [95% CI 0.315-0.437], p < 0.001) and the Ringer group (beta = 0.363 [0.273-0.452]; p < 0.001). Albumin administration in the whole cohort (beta = -0.156 [-0.201 to -0.111]; p < 0.001) and high intraoperative albumin concentration in the Ringer group (beta = -0.07 [-0.140 to -0.003]; p = 0.04) associated with reduced CK-MBm. Compared with ischemia-induced increase in CK-MBm, albumin's potency to reduce CK-MBm was 41% in the whole cohort (beta-value ratio of -0.156/0.376) and 19% in the Ringer group (beta-value ratio of -0.07/0.363).Conclusion: Both endogenous and exogenous albumin appear to be cardioprotective regarding CK-MBm release in on-pump cardiac surgery.