Red blood cell transfusion is a determinant of neurological complications after cardiac surgery

Abstract

Objectives: The aim of this study was to evaluate the impact of red blood cell (RBC) transfusions on the occurrence of stroke and transient ischaemic attack (TIA) after cardiac surgery.

Methods: Data on 14 956 patients undergoing coronary artery bypass grafting (CABG) and valve surgery (with or without concomitant CABG) were retrieved at three European University Hospitals. The prognostic impact of RBC transfusion on postoperative stroke and TIA was investigated by logistic regression and multilevel propensity score analysis.

Results: Postoperative stroke was observed in 147 (1.0%) patients and combined stroke/TIA in 238 (1.6%). Of the total population, 6439 (43%) patients received RBC transfusion with a median of 2 units (25th-75th percentile, 2-4 units). When adjusted for other significant risk factors, RBC transfusion was an independent predictor of stroke [odds ratio (OR) 1.14; 95% confidence interval (CI) 1.11-1.17 per unit] and stroke/TIA (OR 1.12; 95% CI 1.09-1.15 per unit). Increase in the amount of transfused RBC units was associated with higher rates of stroke (no RBC transfusion: 0.5%, 1-2 RBC units: 1.0%, OR 1.42; >2 RBC units: 2.7%, OR 3.10) and stroke/TIA (no RBC transfusion: 0.8%, 1-2 RBC units: 1.8%, OR 1.49; >2 RBC units: 4.0%, OR 2.72). Multilevel propensity score analysis confirmed these findings and showed a very high risk of stroke (3.9%; OR 3.85; 95% CI 2.30-6.45) and stroke/TIA (5.9%; OR 3.30; 95% CI 2.17-5.02) associated with transfusion of ≥6 units of RBCs.

Conclusions: Transfusion of more than 2 units of RBCs after cardiac surgery is associated with a significantly increased risk of postoperative stroke and TIA.

Keywords: Aortic valve; Blood transfusion; Cardiac surgery; Coronary artery bypass; Mitral valve; Stroke; Transient ischaemic attack.