Objective: Fast track recovery protocols on younger, low risk patients result in shorter hospital stays and decreased costs. However, data is lacking on the impact of these protocols on high risk patients based on an objective scoring system. Methods: In this study, a high risk cohort of patients (EuroSCORE greater than or equal to6, n = 158) was compared with a low risk cohort of patients (EuroSCORE < 6, n = 1004) to define the safety and efficacy of fast track recovery among high risk patients. A standard perioperative data is collected prospectively for every patient. Results: Time to extubation was longer in the high risk group (299 +/- 253 vs. 232 +/- 256 min; P = 0.003), but intensive care unit (ICU) stay (25.6 +/- 28.7 vs. 21.5 +/- 9.4 h; P = ns), and postoperative length of stay (5.8 +/- 2.4 vs. 5.6 +/- 2.7 days; P = ns) was similar when compared with the low risk group. Of the high risk patients 81% were extubated within 6 h, 87% were discharged from the intensive care unit within 24 h, and 67% were discharged from the hospital within 5 days. Multiple regression analysis showed that any red blood cell transfusion (P = 0.02), and cross clamp time > 60 min (P = 0.03) were the predictors of delayed extubation ( ! 6 h) in the high risk group. The predictors of extended ICU stay were any red blood cell transfusion (P = 0.0001), and peripheral vascular disease (P = 0.05). Any red blood cell transfusion was the only predictor for mortality (P = 0.02) and readmission to the hospital within the first 30 days (P = 0.02) in this cohort of patients. Conclusions: This study confirms the safety and efficacy of fast track recovery protocol among high risk patients undergoing coronary artery bypass surgery. All patients are basically suitable for fast track recovery and the preoperative risk factors are poor predictors of prolonged ventilation, increased ICU and hospital stay. Red blood cell transfusion is associated with delayed extubation and discharge from the ICU, and increased mortality and hospital readmission rate. (C) 2003 Elsevier Science B.V. All rights reserved.