The use of the stroke risk index to predict neurological complications following coronary revascularisation on cardiopulmonary bypass.

The aim of this study was to investigate the validity of the stroke risk index (SRI) in identifying patients who develop a stroke following coronary artery bypass grafting on cardiopulmonary bypass. Retrospective data were analysed from 6846 patients who underwent adult coronary artery surgical procedures on cardiopulmonary bypass between 1997 and 2003. Patients were risk stratified pre-operatively using the SRI assessment model into low (Group A ≤ 50), medium (Group B, 51-100) and high risk (Group C, > 100). A total of 217 patients (3.2%) with a mean age 65.9 ± 11.7 years developed adverse neurological events following surgery. The CNS injury risk was 4% in Group A, 23% in Group B, and 8% in Group C. Pre-operatively, patients in Group B were older (p < 0.05), had a greater proportion of redo operations (OR 3.02; p < 0.001), diabetes mellitus (OR 2.51; p < 0.05), hypertension (OR 1.64; p < 0.01), myocardial infarction (OR 3.79; p < 0.05), ejection fraction < 30%, (OR 1.46; p < 0.01) and absence of sinus rhythm (OR 2.52; p < 0.05) when compared with their counterparts. CNS events increased the patients' hospital stay by 40% in Groups A and C (p = 0.04) and 72% in Group B (p < 0.001). Only 31% returned home, compared with 85% of patients without cerebral complications (p < 0.001). These findings demonstrate that factors such as a pro-operative history of redo procedures, myocardial infarction, ejection fraction < 30% and absence of sinus rhythm play an important role in identifying the at-risk population. We conclude, therefore, that a further refinement and validation of the SRI is necessary.